Gardening Terminology: Strange Gardening & Botanical Words That Are Important For Gardeners


Learning About Gardening Can Be Confusing With All The New Gardening Words And Names To Remember. So I Asked Gardeners The Following Questions About Gardening Terminology and Wrote a Gardening Dictionary to Help Them Master The Words And Enjoy Their Gardening. It’s Not Made Easier By the Fact Some Of These Words Are Historical And Some Very New.

Which gardening terms confuse you?

What gardening terms are new to you?

What gardening terms do you want explaining?

This dictionary is a work in progress, I’m starting at the beginning with A .. and slowly working through the alphabet. It’ll take time so please bear with me and come back as I write each new instalment!




Gardening Terminology – A 

Abscission Layer

A layer of cells at the base of the petiole (leaf stem) where the leaf breaks away in autumn. Technically there are two layers of cells, in autumn the bottom one expands and breaks away from the top layer. It is believed that reduced sunlight and daylight hours leads to a reduction in photosynthesis and hence a reduction in chlorophyll production which then prompts abscission. in autumn.

Acid Soil

Soil can be acid, neutral or alkaline and is measured on a pH scale of 0-14 with 7 being neutral. Acid soils are technically in the pH 0-7 range. However the most acid soils rarely exceed pH3 and few plants can survive very acid conditions.

The plants that enjoy, and in some cases require acid soils include blueberries, heathers, rhododendrons, azaleas etc. For example, most rhododendron species prefer a pH of 4.5-6. Naturally-occurring acid soils are found in bogs (hence peat is acidic), moorlands and coniferous forests.

Ericaceous composts are acid and used to grow acid-loving plants.


A measure of land totalling 43560 square feet (UK measurements). If its square that’s about 209 feet on each side. There are 2.471 acres in a hectare. Land in the UK is still sold in acres.

To confuse matters even further, historically an acre was a furlong by a chain. Roughly speaking this is the size of a football pitch (which can be anything between 100-130 yards long and 50-100 yards wide .. even square according to the rules!).

Aerate / Aeration

Aerating consists of loosening the soil surface to encourage water and air penetration. It can be done by hoeing and other cultivation practices and is useful to prevent evaporation during hot weather.


Air is often forgotten as essential for plant growth. In most plants, air is taken in via the roots and soil or compost needs to be air permeable to allow for gaseous exchange at root level.

Air drainage

Hot air rises and cold air descends. Air drainage is when cold air flows down a slope. In cold weather this can lead to frost pockets ate the bottom of the slope, where the cold air lays in low spots.

Air Propagation

A form of plant propagation where the cutting is allowed to root into a growing substrate whilst still attached to the parent plant. Some form of damage to the bark, where rooting is required, induces quicker rooting. To prevent that substrate from drying out the stem and substrate is normally wrapped in plastic to retain moisture.

Alkaline soil

The opposite end of the pH scale to acid soils .. see above.



The onion family. There are hundreds of species within this family which includes onions, spring onions, garlic, shallots, etc

Alternate leaves

A plant leaf structure where the leaves appear alternately along the stem as opposed to opposite or in some other structured way

Alternate Bearing

Alternate bearing refers to the tendency of many fruit and nut species to grow large crops every other year with much smaller, or no crop, in the in-between years. It’s like Bienniel Cropping.


A plant that lives for up to a year. They can go from seed to mature seeding plant in no more than a year. Some weeds can actually achieve this in six weeks … it’s why they are so successful at being weeds!


The part of the flower that produces the pollen. It is on the upper part of the stamen.


A fungal disease affecting leaves and fruit


A small sucking insect that sucks the sap from plants. Aphid are parthenogenic and hence capable of virgin birth. Most adults don’t have wings but every so often a winged generation occurs and they fly to infest new plants. Aphid are unusual in the insect kingdom in that they give birth to live young and are not normally egg-laying. There are huge numbers of aphid species and they range n colour from green to pink and even black (often call the black army when infesting broad beans).


A product or substance that kills aphids

Apical dominance

The botanical term that describes the process whereby the main stem of a plant is dominant over the branches and side shoots and where branches are dominant over sub-branches. The process is controlled by plant hormones, auxins, produced in the growing tip. Thus the dominant plant growth is upwards towards better light where photosynthesis is maximised. Should the leading shoot be destroyed or damaged a secondary shoot will become dominant due to the lower auxin level. It then produces auxins to become dominant in its own right. 


A collection of trees and shrubs; often gathered together for scientific or educational purposes, or as in the case of some collectors to demonstrate wealth or intellectual prowess!

Normally arboreta are found in parks or private gardens. Examples in the UK include the National Arboretum at Westonbirt which belongs to Forestry England and Sidmouth arboretum which is unusual in not being a single site in single ownership. Sidmouth Arboretum is a collection of trees and shrubs spread across the whole of the Sid Valley, in the ownership of a number of private individuals and public bodies and organisations.


The cultivation of trees and shrubs as individuals and small groups as opposed to forestry which is the planting, growing and harvesting trees en masse for timber. Arboriculturists work with both ornamental and edible crop bearing trees such as apples, cherries, etc.


A tool designed to take soil samples from various depths OR a tool that makes holes to enable the planting of bulbs, plugs, or container/module or pot grown plants. Augers that fit in hand drills are particularly easy to use and can make planting much quicker. (Please follow the safety instructions provided with your auger).

Average Frost Date

The average date when the first and last frosts can be expected for a given locality.


The leaf axil is the joint between the leaf and stem on a plant. This area is where shoots often emerge. An example would be tomatoes where the shoot coming from the axil is the side shoot.

Axillary bud

The bud produced in the leaf axil.

Gardening Terminology – Back to Top


Gardening Terminology – B

Balled and Burlapped

An American term that refers to how bare-root plants are sometimes sold with the roots wrapped in burlap. In the UK hessian or even plastic is often used. 

Bare Root

Plants such as fruit canes are sometimes sold as bare-root plants rather than in pots. They will have little or no soil around the roots and will be protected from drying out by being wrapped in paper or an alternative cover.

Don’t think that if you’re offered a bundle of plants in a single pot they are necessarily pot-grown. They are often bare-root plants put in a pot to lengthen their shelf life. They weren’t grown as a clump of plants.

Bare root plants are best planted in the autumn when they are more likely to root and establish rather than in hot dry weather when they can dry out and die.


The bark of a tree or shrub is the hard outer layer that covers the roots, stems or trunk. Several other structures exist below the bark including cambium, phloem etc. The outer bark consists of dead tissue whilst the inner bark is living and includes the inner layers of the periderm.

Bark can be harvested for several purposes including as cork for the making of cork goods and as a bottle closure. Oak bark is used in the tanning process. Other barks produce spices, eg cinnamon bark, latex and poisons.

Bark is often visually attractive and many trees are grown for this reason. e.g Cornus species.

Bark is also used as a ground cover in pathways and on beds as a mulch.


As in a blade of grass. Its the flattened green part of the leaf.


These are plants that take two years to go from seed to seeding adult. Lots of veg are biennials, eg lettuce, leeks, carrots, beetroot, but we tend to eat them in year one so never see them flower. It’s a pity we don’t see them as some are magnificent, leeks, for example, can be six feet high when flowering and have a huge head of flowers.

snails grazing on food crops can be controlled with nematodes - Gardening Terminology

Biological Control

The use of biological agents to reduce pests. E.g the parasitic Encarsia formosa wasp to control whitefly. Other examples include Bacillus thuringiensis to control caterpillars and nematodes to control slugs and snails.


A leaf structure where the leaf is compound with a paired leaf of feather-like leaves. Each pair is also divided into pairs.

Gardening Terminology -Bipinnate leaf structure
Bipinnate leaves

Bolt / Bolting

When a plant bolts it means it’s going to seed. This is exactly what we want if we harvest the seed or fruit. But not so desirable if we want the root or foliage. Premature bolting is often caused by water stress .. ie underwatering or overwatering.

Bone meal

A phosphorus-rich fertiliser made from finely ground up animal bones. Phosphorus promotes strong root systems and is part of a normal general-purpose fertilizer.

Botanical Name

The two part (binomial) naming system, devised by Linnaeus, used for plants and animals. Eg Digitalis purpurea, often shortened to D. purpurea. The first part of the name, the Genus, is always capitalised and the second part, the species, is not,


The scientific study of plants including their physiology, structure, ecology, genetics, classification and economic importance.


Botrytis cinerea is a fungus, often called grey mould or grey rot, that infects a wide range of fruit, veg and flowers. It tends to be more prevalent in wet or moist conditions and often infects plants that have been damaged in some way. Eg. tomatoes that split due to sudden increases in irrigation will frequently get botrytis. It is also very common on strawberries and grapes.

Botrytis is necrotrophic, ie it lives on dead plant material. In many cases infecting damaged plants and subsequently causing their death.


The modified leaves, often sitting below the flower, that are often mistaken for the flower. Examples include bougainvillaea, poinsettias and some dogwoods (Cornus species).


A bract-like structure sometimes found between bract and flower. 


The cabbage and mustard family. The genera include many species and cultivars. Eg Brussel sprouts, cauliflower, kale, turnip, kohlrabi, broccoli, calabrese, pak choi, swede, etc


No, not a media term! In this case, it means to broadcast seed, ie to spread seed widely by hand or with a machine.  A hand-operated machine called a seed fiddle can be used to sow seed.  I’ve used one myself to sow grass seed and it’s claimed that it can be used to sow wildflower seed. However, the problem with using it for mixed seed is that each seed has a different weight and therefore is broadcast a different distance. This means there is a tendency to get stripes in the field where the lighter seed hasn’t reached! The video shows a seed fiddle being used in Scotland, and the accent may need some careful listening if you are to understand it fully. 


Buds are undeveloped or embryonic shoots and what leaves, flowers and subsequent seeds or fruit will develop from.


A bulb is an underground storage organ typical of the daffodil and lily families. It is effectively a self-contained bud, that can remain dormant when growing conditions aren’t good, that can be detached from the parent plant and will remain viable. It consists of a stem surrounded by fleshy scale leaves and flower. The embryonic flower is contained within the bud and will have formed between the time the plant last flowered and the time the bulb was finally formed. Blind bulbs have no flower embryo and are usually formed when the plant has been too dry after flowering or the foliage has been damaged before the bulb has been fully formed.

Gardening Terminology  – Back to Top

Gardening Terminology – C


The stem of fruit canes such as blackberries, raspberries, loganberries, tayberries, etc .. not forgetting bamboo canes and sugar cane. Generally speaking, canes are slender hollow plant stems.  


Chalky soils are largely calcium carbonate based and hence lime rich. They are very alkaline eg. pH of 7.1-8.0, they will often froth if mixed with a mild acid such as vinegar. Where this occurs it demonstrates the presence of free calcium carbonate.

Chalky soils are highly visible. They appear to be white, or at least have small pieces of chalk in them.

Chalky soils are often shallow and overlie clay. The chalk itself will be free draining but the underlying clay will be wet and cold. This makes it a difficult soil to cultivate and grow crops in. Organic matter such us composts can be added to improve fertility but it decomposes quite rapidly.

Poor growth and chlorosis are common on chalky soils. This is due to plants not being able to absorb sufficient iron and manganese due to the alkaline conditions.


Plants respond to certain chemicals and are said to be exhibiting chemotropism. This can be seen within the soil when plants move toward nutrient-rich soils and in the flower when the pollen grain germinates and is attracted towards the ovary which releases chemical signals.


The process where seed potatoes are placed in hitting trays in a bright, frost-free place so they can sprout before being planted. 


Chlorosis, and chlorotic growth, are characterised by yellowing of leaves due to the lack of chlorophyll. Although indicative of various adverse conditions such as poor light, pest and disease including viruses, poor nutrition, waterlogging, drought, low temperatures, incorrect pH or other cultural problems it is also natural in some cases. For example, young shoots are often chlorotic when they emerge from the seed, but green up quickly provided they get sufficient light.

Interveinal chlorosis is sometimes indicative of iron, manganese or magnesium deficiency. This isn’t necessarily indicative of low levels of these microelements in the soil or growing medium but is sometimes caused by the plant’s inability to mobilise them quickly enough. In the case of magnesium deficiency, this can be remedied bus foliar feed. For example, tomatoes sometimes run out of magnesium when at the 5-6 truss stage and can sometimes benefit from a foliar feed .. Epsom salts are the usual ingredient for this feed which is sprayed on the leaves in the early evening or other time when strong sunlight is absent.

A lack of nitrogen is also a possible cause of yellowing or reddening of leaves, especially older leaves. where the second indicator is a lack of plant vigour characterised by slow growth.

Leaves also go chlorotic in the autumn as the plant withdraws valuable nutrients from the leaves before shedding them.

Clay/ Clay Soils

A soil component measuring less than 0.002mm.

Clay soils are predominately composed of very fine granules and colloidal substances. The clay component of soil measures less than 0.002mm.  Clay soils crack when dry and become very sticky when wet. This makes them a cold soil that is slow to warm up in spring and can bake hard in summer. The fact they can bake hard is why some clays are used to make bricks.

Clay soils are rich in nutrients and can range in colour from white or dull grey to orange or dark brown.

Most soils contain some clay and a small amount is beneficial. However, when it predominates it is a difficult soil to cultivate and grow crops in.


From the French for a bell, a form of plant protection, the original ones were glass and made in the shape of a bell.

Today the range of cloches is much wider with continous plastic covered hoops that form a mini tunnel being available in many garden centres.

Recycled plastic bottles are often used as a form of plant cloche by many gardeners.


Plants that are produced asexually either as seed or via stem or root cuttings are clones of the parent plant. This means they have exactly the same genetic composition ie they are genetically identical.

Clones occur naturally in some species and are used as a means to reproduce. In some cases, they shed branches or twigs that can then root nearby. In other cases, they form clonal colonies. Elm trees are an example of reproduction by clonal colonies via suckering.

Dandelions are an example of a plant that is capable of a plant that can produce asexual seeds via a process called apomixis.


Some plants naturally form clumps rather than individual plants. They tend to be perennials.

Clump-forming vegetables include shallots and chives.

Cold Frame

An unheated frame made of plastic or glass for acclimatising or growing on plants. Sometimes they are used in conjunction with a hotbed/compost bed to supply gentle warmth to a crop during the process of growing or acclimatising. The Victorians used cold frames in conjunction with hotbeds to grow melons and other crops that prefer warmth and bottom heat early in the season. 

Complete Fertiliser

A fertiliser that contains all three of the major or micronutrients essential for plant growth, namely nitrogen, phosphorus and potassium. (N, P, K). Complete fertilisers are often referred to as General Purpose fertilisers.


Compost is composed of organic material that has decomposed in a process called composting. Those sold in garden centres has usually been composted on an industrial scale though it is easy to compost smaller amounts of organic matter on a garden scale.

Peat is also composed of organic material but is not normally referred to as compost. Indeed many composts are sold as peat-free composts due to the negative conservation issues attached to peat use.

Compost is nutrient-rich and if made well is free from pest, disease and weeds due to the high temperatures achieved during the composting process.

Composts include seed composts, ericaceous composts, loam-based compost, peat-based compost, organic compost, peat-free compost, leaf compost, potting composts, multi-purpose compost etc. All of these have slightly different purposes and makeup including pH and fertilizer levels

Compost is used as a soil conditioner, fertiliser and growing medium.

Compost Essentials

Always check the pack to see what it is recommended for and always try to use the right compost for the right job.

Try to avoid composts that include peat.

Check your soil pH before using compost as a soil conditioner.

When setting seed always firm the compost and water before sowing the seed. This prevents air pockets from forming and ensures that the compost is moist enough.

Composts can often be reused if additional nutrients are added. But ensure that drainage is not impeded in old composts that have “slumped”.

Don’t sow seeds in ericaceous or high nutrient composts as the conditions will be adverse in most cases.

Before replanting pot plants in new compost always soak the existing root ball in a bucket of water for at least an hour. Once repotted water again to settle the compost. This ensures it will not dry out in the new compost.


Unlike deciduous trees, coniferous trees keep their leaves during winter. This means they have to grow more secure roots to ensure they don’t blow over in storms. 


A pot or other receptacle for growing plants

Controlled Release Fertiliser

A fertiliser that has been manufactured as a prill of in other form designed to release nutrients in response to temperature or moisture stimulus

Cool Season Crop

Crops that thrive in cool conditions. They dislike excessive summer temperatures which often makes them bolt. Excess heat slows down the enzymes that drive photosynthesis and slow plant growth. 


Cordon grown fruit include tomatoes. The plant, in this case, is sideshooted to allow a single cordon to dominate the growth. Cordon systems are used in commercial horticulture as a form of vertical growing.


An underground storage organ found on plants such as gladioli, cyclamen etc. Corms consist of a swollen stem base plus a number of scale leaves. 

Very few vegetables form corms, examples that do include eddoe and taro.


Cotyledons; of which there are two sorts, monocotyledons and dicotyledons, are used to refer to plant seed leaves. in a wider sense, they refer to the two groups of flowering plant types that are defined by the nature of their embryonic seed leaves.

Examples include grasses and cereals which are monocots and plants such as the Solanaceae and Cucurbitaceae .. the tomato, pepper and potato family and the cucumber, marrow, squash family which are dicots.

Cover crops

Cover crops are grown when main crops are not being grown. They decrease erosion and can be used to increase fertility when ploughed in. For example clover and other leguminous crops might be grown and dug in to increase fertility, especially nitrogen levels.

Cover crops may also be harvested for composting. this is of special interest when no-dig systems are employed.

Crop Rotation

Mankind soon discovered that pests and diseases were more prevalent where the same crops were grown each year. Farmers therefore developed systems whereby crops were rotated. Hence they might only grow potatoes on a patch of land every 5-6 years. The other crops in the rotation would depend on the locality, altitude etc. In the warmer, wetter, west of the country grass for grazing animals would be included in the rotation. Elsewhere it would not and a typical farm rotation would be Turnips in year one, followed by barley which was undersown with clover and ryegrass. The grass and clover then lasted two years and helped to build fertility. Turnips could be replaced with potatoes if preferred. Sheep were an essential part of the process as they ate the turnips and grass and fertilised the soil with their droppings. 

The above was referred to as The Norfolk Four Course Rotation and was revolutionary when it was developed as it replaced a fallow, and hence unproductive, year in previous systems. 

An alternative was the Norfolk Six Course Rotation which consisted of corn, turnips, corn, corn, grass, grass. We can thank “Turnip” Townsend for the four-course rotation and Coke of Norfolk for the earlier six-course rotation which he developed on his Holkham estate. Today at Holkham they grow a new ‘Six Course Rotation’ of oilseed rape, winter wheat, sugar beet, winter wheat/spring barley, potatoes and winter barley/winter wheat.

Elsewhere, the ability of mankind to use chemicals to control pests, and diseases and fertiliser to control fertility, has led to monocultures.  

On a garden scale crop rotations are still preached by many. However, I am among the increasing number of people adopting the No-Dig gardening system and I’m aware of crops being successfully grown on the same land for years. Eg.  a colleague has grown potatoes on the same land for six years with no decrease in yield and no blight issue. 


Cross-pollination refers to the need in some species for two or more plants of the same species to pollinate one anothers flowers if a crop is to result.   It is necessary in contrast to self-fertile species. 


Found in plants such as rhubarb and asparagus, the crown technically is the growing point of the plant from which new shoots emerge at soil level or just below. However, the word is also used to describe the whole plant when we buy rhubarb crowns or asparagus crowns. 


Cultivar is short for cultivated variety and is commonly used to describe ornamental or decorative flowering plants.


A tool used to cultivate the soil

Cultivations – To Cultivate

Cultivations are the mechanical process of turning and or breaking the soil to produce a seedbed. The word is sometimes expanded to include intercrop/row cultivations that are used to weed between plant rows.

Cultivations break the soil crust allowing both soil aeration and improved drainage/water penetration.


One of a series of ways to propagate plants. In this case, propagation is achieved via root or stem cuttings. Sometimes a rooting hormone powder is used to speed the growth of roots from the stem. Stem cuttings include softwood, semi-hardwood and hardwood cuttings depending on the species, time of year etc.

Gardening Terminology – Back to Top

Gardening Terminology – D

Damping off

A fungal disorder whereby seedlings die due to the stem rotting off at soil level. Sometimes the seeds fail to germinate due to the same fungi. Prevention includes using sterile composts, good air circulation, clean water sources and ensuring the compost is not over watered. 


The process of removing dead flowers to encourage more flowering. Seed production produces hormones that discouraged more flowers. Hence if the flower heads are removed there is no seed produced and more flowers will usually follow. 


Deciduous trees and bushes are those that shed their leaves in autumn and do not regrow them until spring.  The process is determined by cells within the abscission layer of the leaf – see abscission layer.  This offers many benefits. Toxins that have built up in the lives are removed, the old leaves are then available for recycling back into the plant. In addition, the absence of leaves means that wind rock is reduced. If all the branches had a full contingent of leaves it would be badly affected by strong winds and storms and could be blown over.

Coniferous trees keep their leaves and need to anchor more strongly to the soil to ensure they are not blown over in storms. 


Where a plant shoot eg the main stem in tomatoes, ends in a flower bud(s) it is said to be determinate. 

In tomatoes this means that the main stem grows to a given height, usually with 5, 7 or 9 leaf axils before terminating in a flower truss. It then stops growing upwards and can not be trained as a cordon plant. It is in effect a bush, hence the term, bush tomato. In this form, each leaf axil consists of a leaf AND a side shoot. Each side shoot will also be determinate and will effectively make the bush even bushier. 

Dibber or Dibble stick 

Gardening Termnology - Dibber or dibble stick

A pointed stick or tool used to produce holes for plants. seeds or bulbs. 


A botanical term to describe plants that have male and female flowers on different plants. The female flowers are unable to be fertilised without a male plant being nearby to enable pollen transfer via insects, birds, wind or whatever mode is employed. 

Direct Drill

The process of sowing or drilling seeds by hand or machine in their final positions. ie where you want them to flower or crop. 


A much misused gardening word! Dirt is something we get on our hands when gardening. It’s not what we grow crops in. That’s soil or compost.


Large clumps of perennials often benefit from being divided every 3-4 years in autumn or early spring. This entails splitting the clump into a number of plants each with roots, stems etc.  

Dormant / Dormancy 

Seed often exhibit dormancy at certain times of the year or until the right conditions are available. Eg. warmth, daylight etc. 

Plants also become dormant at certain times of the year e.g. after leaf fall in autumn. Though plants appear dormant it is often the case that they are producing root underground and cannot be said to be truly dormant. This is why autumn planting of bare root and pot-grown trees is often more successful, due to the fact they have made root over winter and have established. 


A straight narrow furrow in the soil or compost in which seeds are sown.

Sometimes used to denote the row in which plants can be transplanted.

See also Broadcast

Drip Irrigation

See Trickle Irrigation 

Gardening Terminology – Back to Top

Gardening Terminology – E

Earth Up or Earthing Up

A common term in potato growing, though it can apply to other crops, where the soil is drawn up around the plant to protect from frost/exclude light etc. In potatoes, it may encourage more roots to develop from the stem that is covered. 

Though not technically earthing up the addition of adding more grass clippings to No-Dig potatoes serves the same purpose. 


Electrotropism is a plant’s response to an electric field. For example, pollen tube growth is affected by an electric field. 

In some cases, the electric field can have a negative or even lethal impact on plants and in some cases it is positive. 


Ericaceous refers to lime hating plants that therefore require an Acid Soil or compost. Hence we have ericaceous composts that have been designed for them.

Plants in the ericaceous category include blueberries, heathers azalea, and rhododendron

Ericaceous Composts

Ericaceous Composts are designed with a high pH to grow ericaceous plants. Eg. camellias, azaleas, rhododendrons etc. This is particularly useful when growing in pots, planters and boxes and to a lesser extent in beds and borders. In the later care must be taken to ensure that the pH changes with rainwater incursion.


Soil erosion is caused by rain, wind, water flow and wind and can seriously deplete soils. Bare soils erode much faster than those with vegetation or other cover and hence many growers and farmers grow cover crops at certain times of year to decrease erosion.


A form of pruning trees and shrubs that produce lateral growth at the expense of height. This makes fruit picking far easier. It also reduces competition between branches and increases airflow through the plant structure, often reducing diseases and improving ripening.

Etiolation & Etiolated

Gardening Terminology - Etiolation
An etiolated tomato plant

Etiolation is the technical word used when we say a plant is “drawn”. Etiolation in flowering plants happens when they are grown in poor, partial or complete absence of light. They respond with long, weak stems; smaller leaves due to longer internodes, and turn pale yellow in colour due to the lack of light (chlorosis). What we think is adequate light often isn’t enough for plants and they get very drawn in their search for better light.

Etiolation is the process of becoming etiolated.


The physical process by which liquid water returns to the air. It is speeded by higher temperatures and wind.

Evaporation is important in the process of transpiration.


A term used to describe some strawberry varieties that produce a small crop over a very long period, from spring through to summer/autumn. They often finish the season with a good-sized cropping spurt towards the end of the season. 


Evergreen plants do exactly what their names suggest. They remain evergreen throughout the year, they do not shed their leaves. This is sometimes influenced by the climate and/or weather conditions.

Most, but not all, conifers are evergreen. Eg. the dawn redwood (Metasequoia glyptostroboides) is a deciduous conifer.

Gardening Terminology – Back to Top

Gardening Terminology – F


F1 or F1 Hybrid

The first filial generation that is the result of breeding together two distinct purebred lines. They often show Hybrid Vigour and produce very uniform plants. However, plants produced from their seed obey Mendell’s Laws and do not breed true. 

Feathered Maiden

A one-year-old tree that consists of a single main stem AND a number of side branches or feathers. 


Often confused with fertilising. We feed a plant when we add nutrients to it’s soil/compost or water.


Another much misused gardening word. When a plant is fertilised it signifies sexual reproduction. It doesn’t mean the plant has been fed.


Plant food. Plants need a range of major, minor and trace nutrients to survive, grow and reproduce. The major ones are Nitrogen, Phosphates and Potassium that are usually represented as NPK. Minor and trace elements include magnesium, zinc, calcium, sulphur and iron.

Plant nutrients occur naturally in soils and composts but not always at a sufficiently high level to allow the required level of growth. Hence gardeners and growers need to add more fertiliser.

Where No-Dig is employed the plant nutrients come from the compost added to the surface and this is generally done once or sometimes twice a year. In other cases fertiliser may need to be added before planting each crop. It is then sometimes topped up during the growth of the crop.

Fertiliser can be purchased as organic or inorganic (artificial) fertilizer and can be in liquid or solid form. In many cases it needs to be broken down in the soil by bacteria and dissolved in water before it is available to the plant.

Although the idea of being organic appeals to many people, the plants can’t tell the difference between organic and non-organic fertilisers as they are taken up by the plant in exactly the same way.

When growing commercially and now on a garden scale I’ve used Vitax Q4 as a granular base dressing fertiliser for general use and Tomorite as a liquid feed for tomatoes, peppers, courgettes, aubergines, cues etc.


In botany, the filament is that part of the flower that supports the anther. Its a stalk or stem-like structure 

First Earlies

A potato cultivation term. First Earlies are normally harvested in around ten weeks from planting, though the exact timescales will depend on chitting, soil temperature, planting date and other variables.

First early varieties are however the fastest maturing varieties and include Rocket, Orla, Red Duke of York, Pentland Javelin, Foremost etc. These are best suited for new potatoes or baby potatoes. 

I’m often asked about fertiliser. I use Vitax Q4 as a general purpose fertiliser. And Tomorite for tomatoes, cucumbers, aubergine, peppers and chillis.


Horticultural fleece is a thin, light woven material with a high light transmission that can be used to cover crops. It reduces weather damage, keeping crops warmer and reduces pest damage by preventing access to butterflies, carrot fly etc.

Fleece comes on various weights, the heavier ones lasting longer. Fleece is permeable to air and rain.


Floricane growth is the second year’s growth of a cane that fruits in the second year. As opposed to a primocane which flowers and fruits in the first year. 

Floricanes varieties are often described as flowering/fruiting on old wood. 

To help prevent carrot fly you can cover the crop with fleece, which lets light, air and water in but keeps carrot fly out.


A plant’s leaves are its foliage.

Food Forest

A Food Forest to Forest Garden is a collection of edible or useful plants grown in as near natural conditions as possible. It aims to mimic natural ecosystems with three-dimensional designs where the plants and food grow up, down and sideways. Hence the food produced can include roots, ground-level crops and high-level crops such as top fruit. 

Forests, however, go further and seven layers are normally recognised. These include the

  • Root Layer 
  • Ground Layer
  • Vine Layer
  • Herbaceous Layer
  • Shrub Layer 
  • Understorey Layer and Overstorey Layer
  • Some people also recognise an eighth layer, the Mycelial Layer comprising fungi of all sorts. 

Typical food plants grown in food forests include Blackberries, Walnuts, Hazel, herbs, Passion Fruit, Kiwis, elderberry, rhubarb etc.  


A substance or material that kills or controls fungi. 


Fusarium is a large group of soil-borne, filamentous, fungi. Some are problematic in gardening and agriculture. Eg Fusarium Wilt in turf and Fusarium Ear Blight in wheat.

Fusarium Patch

Fusarium Patch, commonly referred to as snow mould, is a common fungal disease of turf and lawns. Its caused by a soil-borne fungus, Microdochium nivale, which also colonises cereal ears in cool moist weather.

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Gardening Terminology – G


A group of closely related plant species or other organisms. It sits between species and family. 


Geotropism, sometimes called gravitropism, is the response of plants to gravity. Stems grow upwards away from gravity and are said to be exhibiting negative geotropism. And roots grow downwards towards gravity and are said to be positively goetrophic. 


The process where a seed starts to grow.


The process where one plant is joined to another. This is normally done to control growth. E.g a vigorous apple variety will be grafted on to a dwarfing rootstock. Or a Victoria plum, which is a tall variety, could be grafted to a St Julien A  rootstock which is semi-vigorous, hence creating a tree more suited to a small garden.

Tomatoes may also be grafted and the adverts say they then crop more vigorously. However, as a retired commercial tomato grower, I believe most amateurs can achieve the same yields by adhering to good growing practices and need not pay extra for grafting that will offer them few benefits. 

Green Manure

In conventional growing, this is a crop grown to be ploughed back into the soil. In No Dig gardening, the crop can be incorporated by smothering it under a black sheet or similar until it dies.

Green manures offer many benefits including the prevention of erosion, the addition of organic matter, incorporation of nitrogen when leguminous crops such as clover are grown. In essence, the aim is to increase soil fertility. Legumes are often used as green manure due to the fact they add nitrogen to the soil.


A low growing plant that covers the ground. It can be as a feature plant or used as green manure. In both cases it can be used to smother out weeds, 

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Gardening Terminology – H

Half-hardy Annual 

An annual that is not fully frost hardy and needs some frost protection and hardening off before being planted out. 

Half-hardy Biennial 

A plant that goes through its full life cycle in two years but requires frost protection as it is unable to tolerate temperatures below 0C.

Half-hardy Bulb / Corm / Tuber / Rhizome

A plant that grows from one of the underground storage organs listed above that requires frost protection in winter. In some cases, they will also require protection from excessive moisture and are best lifted and stored dry indoors. 


Halotropism is the ability of a plant to directionally grow in response to salt concentration. It’s a relatively underinvestigated form of tropism and the first scientific reviews I can find are from 2013. In their paper, Halotropism Is a Response of Plant Roots to Avoid a Saline Environment, Galvan-Ampudia et al report on their work with Arabidopsis, tomato, and sorghum seedlings and how they prioritised growth away from a salt gradient

Hardening off

The process where plants become acclimatised to new conditions. It usually applies to plants grown indoors or undercover being moved outdoors but can also apply to plants being brought in from cold conditions to warm dry conditions.

Hardening off is a slow process and best done in steps.

Hardy Perennial 

A herbaceous or shrubby plant that persists for more than two years and is tolerant of winter conditions. Eg low temperatures, snow, wet etc. 

Hardy Shrub / Tree 

A woody plant capable of withstanding winter conditions eg cold, wet, snow etc. Trees and shrubs are normally described as having a permanent framework of branches that do not die back in winter, though they may be deciduous. 


Normally applying to potatoes, the haulm is the leaves and stems of the plant. 

Heavy soil

Heavy soils contain a lot of clay and are generally poorly drained and cold.


Plants such as young sunflowers exhibit heliotropism when they follow the sun, from east to west, as it crosses the sky. This increases the amount of sunlight hitting the flower and increases pollination rates. Some plants are able to return the flower to an east-facing position overnight, ready to gain the greatest benefit from the sun. 


A herbaceous plant is non-woody and therefore dies back in winter before resuming growth in the spring. The dormant period is survived as a root.

In some cases, the term can also refer to plants that die back at other periods of the year due to adverse conditions. Eg during the dry period, which then equates to the European winter. 


A product or substance that kills or inhibits plant growth. 

Heterorhabitis bacteriophora

Heterorhabitis bacteriophora is an entomopathogenic nematode that predates a wide range of insects including ants, fleas, moths and weevils.  


Though intensely studied humus is often ill-defined. It is perhaps best defined as the amorphous product of degraded compost. Ie the dark spongy matter that is left when compost breaks down and no longer has a well-defined composition. It includes animal, plant and microbial remains that have been mechanically degraded but retain their chemical composition.

Humus is an important part of soil organic matter and important as a moisture reservoir.


Hyrotropism is a plants response to water concentrations. When root growth moves towards the water, such as during drought, it is said to be exhibition positive hydrotropism. When soils are saturated and the plant grows away from the water it is said to be exhibition negative hydrotropism.  

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Gardening Terminology – I


A term most often found describing tomatoes and the opposite of determinate. Where the stems or shoots do not terminate in a flower bud or flower truss. Hence indeterminate tomatoes can be cordon trained, as opposed to determinate bush varieties. Cordon trained indeterminate tomatoes are not limited in their height and in commercial tomatoes growing often reach 30 foot or more and are grown as layered plants to keep them accessible for picking.  


A product or substance that kills insects.

Integrated Pest Management (IPM)

IPM is widely used in agriculture and commercial horticulture, and can be employed in gardening as well. It uses a wide array of methods to combat pest and diseases including cultural practices, natural predators and parasites, pest/disease-resistant varieties, pesticides (if all else fails), biological control and physical techniques such as fleece etc.

IPM is not organic but tries to minimise the use of pesticides wherever possible.


Intercropping is the growing of two crops on the same plot of land simultaneously. This can be done to save space because the two crops benefit one another by virtue of encouraging insect predators or providing protection from the weather. In this article and further linked articles, I’ll also discuss other reasons as well as linked concepts such as mutualism and resource partitioning.

An example of intercropping in gardens would be the planting of brussel sprouts between the rows of potatoes a few weeks prior to harvesting the potatoes. The theory is that the sprouts establish before potatoes are harvested. My personal observations are that whilst this can work if the potatoes are dug very carefully, this leaves a very loose root run for the sprouts. Brussel sprouts prefer firm soil to anchor their roots in or they will blow over in strong winds.

A better example might be to plant rows of lettuce between tomato rows a few weeks prior to the toms being ripped out. If the toms are adequately deleafed there is enough light for the lettuce. And if the toms are cut off at ground level, leaving the roots in the ground (they eventually break down and encourage drainage), the lettuce thrive and can mature very shortly after the tom crop is removed. Indeed if we practice cut and come again they can start harvesting before the toms finish.

Another example is to sow fast growing leeks between french beans so that as the beans finish the leeks then grow and mature as baby leeks a few weeks later. For this to work I recommend a fast-growing baby leek variety such as Nipper.

Interplanting leeks into a French bean crop

My last example can be considered as interplanting or undersowing. It is to sow green manure on the land before removing the “nurse crop”. For example, a crop of red clover or mustard could be sown between rows of many crops prior to harvest. Crops such as lettuce and French beans are ideal nurse crops as they can be cut off at ground level without disturbing the green manure.

The advantage to using clover as the green manure is the fact it adds nitrogen to the soil provided we leave the roots in situ.

There is a difference between intercropping and interplanting in my mind, though many people consider them as being the same. For me Interplanting is a temporary process as illustrated by the Brussel sprouts example above. The plants share the same space for a short period of time. Intercropping is different. I define it as being two crops sharing the same space and being harvested whilst sharing that space. An example would be to grow climbing beans with a crop of maize or sweetcorn. The sweetcorn provide a support for the and both are harvested in situ before they are both ripped out at the end of the season.

Forms of Interplanting & Intercropping

Relay planting

This is the classic example where the second crop matures after the first has finished. Eg the Brussel sprouts and potatoes cropping.

Mixed cropping

Where two crops are mixed together in a random way (in other words not in rows). This is common in flower beds but less so in veg gardening. It can include two varieties of the same crop eg different colour carrots or beetroot. Or it can involve mixing different species together. An example would be mixed winter cropping as sold by some seed companies. Here they mix things like Chinese cabbage with Swiss Chard, Lettuce, Rocket and/or other mixed leaves.

Row cropping

The traditional Aztec Three Sisters of sweet corn, beans and squash grown in rows is a typical row Intercropping practice.


A plant that invades or has the potential to do so. This can include ornamental plants or those normally termed weeds. Eg some bamboos can become invasive as can rhododendron.  Himalayan Balsam is an invasive “weed” often seen in hedgerows and next to waterways. 


The process of supplying water, and sometimes liquid feed, to crops. Systems range from water channels, irrigation systems such as Overhead, Trickle (Drip) and Rainguns, as well as low tech solutions such as watering cans! 

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Gardening Terminology – J

John Innes

The John Innes Centre is located in Norwich, Norfolk and is an organisation focusing on plants, plant genetics, and related microbial sciences. The organisation commenced in 1910 as the John Innes Horticultural Institution and was then based in South London.

John Innes Composts

These composts were developed at the John Innes Centre and are soil-based composts used in a range of horticultural situations. The compose a seed compost plus a range of numbered composts designed for specific purposes.

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Gardening Terminology – K


The chemical symbol for Potash, a major plant nutrient and fertilizer component.

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Gardening Terminology – L

Land Classification

In the UK land is divided into five major classes, from class 1-5. Class one is the best land, very fertile, able to grow the best crops and is the most expensive. It is predominantly found in river valleys and in the predominantly vegetable growing areas of Lincolnshire. They are usually alluvial soils, predominantly silts. The other class one lands are peat-based. In both cases, they must be well-drained and not prone to flooding or they would not be regarded as class one.

Class 5 is very poor land, unfit for growing agricultural crops, often flood-prone.

Class 3 land is subdivided into several subsets and is “average” land with various characteristics.

Lateral bud

A lateral bud forms in the apex between the stem and a leaf petiole. Lateral buds grow into shoots such as tomato side shoots.


A propagation method where a low hanging branch or shoot is secured in the soil, whilst still attached to the parent plant until it forms roots and is able to be detached from the parent plant.

Leaf compost or Leafmould

Leaves take a long time to compost but make an excellent rich compost that is dark and earthy. It is very moisture retentive and is an excellent addition to other composts where moisture retention needs to be improved.

To make leaf mould leaves should be collected in autumn and held in a compost bin constructed of chicken wire. Alternatively, some people suggest you collect the leaves with a lawnmower as this shreds them, add them to a large plastic bag, wet them thoroughly, tie the bag neck, pierce the bag for drainage and leave for two years.

I find both methods work. However the former works quicker if you turn the leaves a few times to aerate the heap.


Calcium compounds of various sorts are referred to as lime. They are generally used to reduce soil acidity and can persist for long periods in the soil. 

Some soils are chalk-based and hence “lime rich”. 


Loam is a mix of predominantly sand and a smaller quantity of clay particles along with other soil particles. The proportion of sand to clay subdivides loam into sandy loam, silty loam, sandy clay loam, silty clay loam and clay loam.

Loam-based Compost

Loam-based composts have a percentage of loam added to them. This makes them heavier, hence less likely for pots to blow over, and less likely exhibit rapid temperature fluctuations.

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Gardening Terminology – M


Minor plant nutrient. Where plants suffer a deficiency it can be remedied by a foliar feed containing Epsom salts.


Organic material from the farmyard. The droppings of farm animals, normally mixed with straw or other bedding materials.

See also Green manure.


An organic layer of material that is spread over the surface of the soil, between the plants, to control weeds, hold in moisture and, in most cases, to improve fertility. Materials used include compost, spent mushroom compost, woodchip, straw, leaves, leaf mould, grass mowings, etc.

Multi-purpose compost

Multi-purpose compost comprises more than one compost, each with varying constituents. Some will be enriched with nutrients and some not. They may be organic or not and may be peat-based or not. Some will have John Innes added. So look on the pack to see what each pack is recommended for a most don’t really live up to the name multi-purpose!


When plants are grown close together many people consider there to be benefits to both crops. This might include pest control where one crop attracts predators to a pest on the other. I discuss this under Beneficial Insects

In other cases it is claimed that a crop can deter pests that depend on smell, from another crop.

An oft-quoted example is the planting of Tagetes (french marigolds) with tomatoes where it is claimed that the smell of the tagetes confuses whitefly that then doesn’t target the tomatoes. another would be the growing of alliums to deter carrot fly.

Research is not totally supportive of the above ideas. Indications are that it works in only 53% of studies.

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Gardening Terminology – N


A plant that was, or is, found in a specific place. Eg potatoes were native to the Andes. 


Nematodes are microscopic parasites of a range of garden pests. They offer the opportunity to use biological control methods rather than chemical control methods in the garden and on the farm.

Eg include the Slug nematode Phasmarhabditis hermaphrodita, Steinernema kraussei used to control vine weevils, Steinernema feltiae as an ant and leather jacket control, Heterorhabitis bacteriophora to control Chafer grubs, or you can buy a mix of nematodes in one pack that will control:-

  • carrot root fly
  • cabbage root fly
  • cutworms
  • onion fly
  • sciarid fly
  • shore fly
  • caterpillars
  • gooseberry sawfly
  • thrips
  • codling moth


Nitrogen is a major plant nutrient required for growth, especially of green material such as stems and leaves. It occurs naturally in the air and at low levels is dissolved in rain. Leguminous crops produce nitrogen in association with nitrogen-fixing bacteria in root nodules. The nitrogen is available to the leguminous plant eg clovers, beans, peas etc. when it is growing and is released and made available to other plants when the leguminous plant dies.

No Dig Gardening

A gardening technique that involved no digging or ploughing of the soil. A mulch is added to the soil surface which suppresses weeds and feeds the soil and hence plants. Plants are sown direct or, preferably planted by using plant plugs/modules and a dibber.

No Dig has much to commend it, especially reduction in labour and effort to prepare the soil, and elimination/suppression of weeds.

In the first year many practitioners lay cardboard on the soil surface and then add mulch as this further inhibits weeds in the first season.


A species that does not originate from where it is now growing. 

No-Till Gardening

See No Dig Gardening


Nyctinasty is the movement plants exhibit in response to their circadian rhythm as opposed to a tropism.  It can apply to both leaves and flowers but not all plants demonstrate nyctinasty. 

Examples can be seen in most legumes that close their leaves at night and reopen in the morning. This isn’t in response to light but is controlled by the plant’s circadian rhythm .. take a pot of legumes into a darkened room and they will open in the morning despite there being no light.  

The speed at which the flowers or leaves close and open is quite slow so watching for it to happen is doomed to failure .. it’s like watching for the tide to change! But suddenly an open flower is closed .. and the tide is going out! 

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Gardening Terminology – O

Open Pollination

Plant species that are pollinated by natural processes. Eg through insect, bird or animal activity, wind, etc. These plants tend to breed true as opposed to F1 hybrids that do not. 


A substance derived from living material.  One that is not manufactured from non-living substances. Can refer to fertilisers, etc and the foods produced from them.

It is often claimed that organic foods are healthier. However, though the cultivation practices may appear to be healthier it is a fact that not all organic materials are safe, Eg nicotine used as a pesticide can be highly toxic to humans.

Conventionally grown foods can, and do, offer the same nutrients as organic foods. However, the flavour is sometimes better, though the reason for this may be more to do with the cultivation and feeding methods than the fact it is organic. 


The organic gardening movement is exemplified in the UK by Garden Organic, the Coventry based charity previously known as the Henry Doubleday Research Association (HDRA).

Garden Organic and similar organisations believe that crops should be grown organically, without the use of pesticides, artificial fertilisers etc whilst embracing natural growing cycles to enhance growth and the environment.

Organic Compost

Because it is made from degraded organic matter people often think that all composts are organic. However the vegetable matter the compost was made from is rarely organic in the Soil Association sense of the word. In addition various chemicals may be added as fertilisers. Being made from organic materials does not necessarily mean the compost is organic. 

Soil Association certified organic composts are available from specialist producers.

Organic Matter

Organic matter is a carbon-based material composed or the remains of plants and animals and their waste products.

The organic matter in soils is derived from degraded plant and animal material plus microorganisms. Organic matter is desirable as it retains moisture and essential plant nutrients.


Plants grown primarily for their decorative or aesthetic value as opposed to being grown for consumption, medical purposes, fibre or other economic use. Some plants can be both ornamental and decorative. Eg the olive tree, cherry trees etc. 

Oscillating Sprinkler

An irrigation sprinkler suited for small gardens consisting of a perforated curved bar sprinkler that oscillates as it sprays water over a plot. The jets of water tend to break up as they hit air resistance and the resulting drops resemble rain. 


The gynoecium, or female, part of a flower.  


Overhead irrigation is the term used to describe a number of irrigation systems used in greenhouses and tunnels. It consists of pipework and nozzles situated at a high level. When activated a raindrop type pattern of water results due to pressurised water hitting the spray head and breaking up into droplets. 

Spray patterns tend to be uneven unless the system is well designed with the water being sprays in a series of overlapping concentric rings. However, it is still one of the most effective watering systems available to the majority of commercial and amateur growers. 

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Gardening Terminology – P


Partially decomposed vegetable matter produced in bogs, fens and other acidic wet environments.

Until recently peat was commonly dug, dried and sold as a compost for growing plants. Digging peat destroys rare habitats and is now largely stopped after environmentalists highlighted the problem.

Peat soils are farmed in areas such as the Fens of England and are extremely productive.

Some soils have a mix of peat in their composition, usually where a thin layer of peat has been mixed with other soil types as they have been farmed over centuries.

Peat-based Compost

Peat-based compost is less common these days due to environmental concerns. At one stage it was the most common compost available to commercial and amateur growers.

Peat-free Compost

Peat-free compost is available from many sources as are reduced peat mixtures. Peat free was problematic when first introduced as it suffered poor drainage and variable quality. That is now largely a thing of the past.

If the pack doesn’t specifically say peat free it is highly likely to contain some peat.


The pedicel is a small stalk in an inflorescence of flowers. Ie a sub stem. In tomatoes, it becomes the tomato fruit stalk and has an abscision knuckle when it naturally breaks during picking. 


The peduncle is a stem-like structure that branches into a number of pedicels. They occur in tomatoes when we have split trusses or multiple branching trusses as commonly found in cherry tomato 


Petals form the corolla of the flower. They are modified leaves, often brightly coloured to attract pollinators,  that surround the reproductive parts of the flower. Though we see a range of colours when looking at flowers, insects including bees, see much more including what are referred to as nectar guides. Nectar guides are seen as ultraviolet markings that lead the bees to the nectar. 


Perennials are long-lasting and may seed many times during their lifetime. Trees are a prime example, think how many acorns an oak will produce in a lifetime that spans centuries. So fruit trees, fruit bushes and even strawberries are perennial. But we aren’t limited to fruit. Perennial kale and asparagus have long lifetimes and keep producing fruit, leaves etc.


Pesticide is the generic name for a group of substances, materials and products that kill or inhibit pests, diseases etc. They include aphicides herbicides, insecticides, fungicides, nematicides, piscicides, molluscicides, avicides, bactericides, viricides, rodenticides, etc. plus all the products and materials, such as repellents, that inhibit pests and diseases.

The word pesticide is often regarded emotively as they are considered to be “chemicals” and therefore not good!  However, water is a chemical and we all need that. And we all need salt in our diets, but it can be used to kill slugs! 

So the use of the word pesticide needs to be more thoroughly considered. 

Pesticides can be natural or manufactured, organic or inorganic. For example, pyrethrum is a naturally occurring insecticide produced by plants of the pyrethrum family. But pyrethroids are products, based on pyrethrum, that are manufactured as an insecticide. Both kill insects.

And organic products may be natural but can be highly dangerous. For example, nicotine is permitted as an insecticide by the organic movement.  It is however highly toxic to humans and can be absorbed via skin contact. 

Many years ago I saw a well-known member of the organic movement making up a nicotine wash for his fruit trees. He was stirring it with his bare hands. He’s dead now! 

OK, the nicotine didn’t kill him immediately but it can kill within hours if a lethal dose is absorbed. And he did die of heart failure a few years later. 


pH is the measure of the hydrogen ion concentration in a substance and is used to measure the acidity or alkalinity of soils. ph 7 is regarded as neutral with lower numbers being acid and higher numbers being alkaline. Most plants prefer neutral or near neutral soil. Ericaceous plants prefer acid soils and there are also plants that prefer alkaline soils are thrive on chalklands. 

Phasmarhabditis hermaphrodita

Phasmarhabditis hermaphrodita is the slug nematode often recommended as a natural molluscicide. It’s the organic way to limit slug and snail damage, without resorting to chemicals. There’s a lot more detail at the following link.


Photosynthesis is probably the most important chemical reaction on earth. Although it happens in plants,  we would die without it.

It’s the process that drives plant growth. In photosynthesis carbon dioxide is taken from the air, water from the roots and energy from sunlight to produce oxygen and glucose via an endothermic process. 

The carbon dioxide is taken in via stomata which are mainly found on the undersides of leaves. Oxygen is then given off via the same stomata. All life depends on photosynthesis. And in producing oxygen the plant absorbs large amounts of carbon dioxide.

The glucose that is produced is used to form more complex carbohydrates, such as cellulose, to enable plant growth. Some glucose is stored in special organs within the plant. For example, the tubers of potatoes, where it is converted into starch. 

In all chemical reactions like photosynthesis, there are limiting factors. For example, a lack of carbon dioxide can prevent the plant growing as fast as it might and when I grew tomatoes commercially the concentration of CO2 in the air was low enough to make supplying additional CO2 to the plants and economic option. Today, with global warming,  CO2 levels are higher. Temperature can also be a limiting factor. Too cool and the plant enzymes that help drive the process are slow, too hot and the enzymes denature and no longer work. Hence temperature is a critical factor, as is sunlight, in plant growth. 

The following video explains this very clearly (its a GCSE biology video designed for school children … but though it feels like being back at school it is actually a very good explanation of photosynthesis and worth watching.  


Phototropism is the directional growth process in plants where they respond to light. Positive tropism is seen when leaves, stems and to much lesser extent branches, grow towards the light. Roots often demonstrate a negative phototropism response.  

Heliotropism is an associated process but is not primarily governed by phototropism. 

Phosphorus / Phosphates

Phosphorus is a major plant nutrient that normally occurs as a phosphate. It is essential for healthy plant growth including the production of oils, starch and strong root systems.

Pinching Out

The process of removing the growing points of plants to encourage bushier growth. Pinching out stimulates side shoot growth. Side shooting is the opposite of this process and encourages the growth of a single leader.  


The female part of the plant. Ie the seed bearing part of the plant that consists of the ovary, style and stigma. 


Aerial roots that are used to obtain oxygen from the air when underground roots become waterlogged. Frequently found on mangroves, banyans there are sometimes apparent on Schleffera, Ficus benjamina and rarely on brassicas and tomatoes.


The process of pollen transfer from stamen to pistil. The process of fertilisation involving the fusion of male and female gametes to form a zygote. 


Potassium is one of the three major plant nutrients and has a role in producing flowers and fruit, fight off disease, produce proteins and aid in photosynthesis

Potting compost

A compost designed specifically for potting on plants or seedlings. Potting composts can be organic or not and are normally enriched with additional nutrients, often with slow-release fertiliser.

Pot on

To move a plant from a small pot to a larger one. 

Pot up

To pot seedlings up is to remove them from the seed tray and put in a pot or other container for them to grow on in.

Prick out 

To take seedlings from trays and replant into pots, containers or the soil. 


Primocane varieties of crops such as raspberries, blackberries etc flower / fruit on new wood. Ie wood that has grown that season, as opposed to floricane cane that fruit on “old wood”. 

Primocane Variety

The varieties of raspberries etc flower on first year canes/wood and are therefore usually autumn fruiting.  Raspberry varieties include Autumn bliss. 

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Gardening Terminology – Q


Quercus (Latin) is the name of the genus of trees commonly referred to as oaks. There are around 600 members in this genus which is part of the Fagaceae family.


Quinoa (Chenopodium quinoa) is a plant grown for its seed and is regarded by some as a superfood. The reality is that it’s been farmed for human consumption in Peru of 3-4000 years and prior to that as animal fodder.

It’s from the Amaranth family which includes Fat Hen (Chenopodium album) which was grown in the Iron Age as a food crop in the UK. The Vikings and Romans also harvested it.

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Gardening Terminology – R


Racemes are flower inflorescences where the flowers are on a single stem, with each flower in a short stalk or pedicel, arising from the stem. The single truss of tomatoes is racemous. However, where the truss is split it is then known as a cyme.


Rainguns are used in outdoor irrigation of vegetables and other high value crops. Static and mobiles systems are available. In both cases, a jet of water is sprayed over the crop after hitting a deflector plate which breaks it into droplets. The result is a mist of fine or larger droplets that resemble rain. 

Mobile systems pull the irrigation head across the field at a steady pace and the spread of water is therefore relatively even across the area irrigated. 


The base of the flower structure from which other structures arise. In strawberries and poms, the receptacle becomes the edible “fruit” 

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Gardening Terminology – S


Sands are one of the coarser constituents of the soil and those soils with more than 85% of material classified as sand are referred to as sandy soils.

The size of sand in soil ranges from 0.05 – 2.00 mm in diameter. 

Sand is derived from rocks that have been broken down by rain, frost, wind etc. Sands composition depends on the rock from which it is derived but is largely silica-based. However, the second most common constituent of sand is calcium carbonate, which is typical of those sands derived from corals and seashells.

Seed Compost

Seed compost is produced for the sole purpose of germinating and growing on seedlings. It is usually open and free draining with a pH around neutral. Other than lower levels of nutrients the compost can contain peat or be peat-free.


The plant when it emerges from the seed and for a few days thereafter.  Typically seedlings consist of three main parts: the embryonic root or radicle, the embryonic shoot/stem (hypocotyl), and the seed leaves (cotyledons).

Self Fertile (Self Pollinating) 

Plants that produce their own pollen and can therefore pollinate themselves are self-fertile. Eg Victoria plum


Sepals, of which each flower has many,  together form the Calyx of the flower. Like the petals, they are modified leaves, but sepals sit below the petals in the open flower. They form a cover over the petals when the flower is closed and are largely what is seen as the flower bud.


Silt, an important soil constituent, is the granular non-organic material that is sized between sand and clay.


Soil is a complex mixture of rock particles ranging in size from sand to clay; minerals, stones, organic matter, chalk, peat, gases, liquids, humus, soil organisms and empty spaces, that is found on the surface of the planet.

Soil is normally recognised as having four distinct functions:-

  • A growing medium for plants of all descriptions.
  • A medium which retains gases, such as CO2, in various forms and hence modifies the earth’s atmosphere.
  • A habitat for soil organisms
  • The filtration, purification, storage and supply of water.

The study of soil in its natural environment is called pedology and there is a range of soil types defined below.

Soil texture 

A measure of the proportion of sand, silt and clay in a soil. If moist soil is rubbed between the finger and thumb clay solid will feel silking whilst sandy solid feel gritty. To determine the soil type it is necessary to actually measure the relative percentage of each component. 

Soil types

Soil is generally classified into loams, clays, silts, sands, peats and chalks.


The male part of the plant, consisting of the anther and filament. 


The Stigma is the part of the flower that receives the pollen and is where it germinates. It is often sticky so it can retain the pollen. Pollen is often desiccated when it is transferred, so the stigma often rehydrates the pollen before it germinates. 

Stigma come in various shapes and forms. Most are relatively small but some, like the maize stigma, is a long silky tassel that is highly visible. 


The style in a flower connects the ovary to stigma. It is usually a short or long tube but is sometimes absent n which case the stigma is referred to as being sessile. 

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Gardening Terminology – T


The term previously used in botany to describe the receptacle.


Thermotropism is a plant’s growth response to temperature. The example commonly quoted is the curling of Rhododendron leaves during cold temperatures. I’ve also observed this in winter grown lettuce in unheated greenhouses. In very cold weather lettuce show some leaf curling, a degree of leaf wrinkling uncharacteristic of the variety and also “hug the ground”, as if for warmth or shelter. 


Thigmotropism is the process where climbing and other plants detect and respond to solid objects. Climbing plants and vines use tendrils to twine around solid objects to gain support for the plant. This is positive thigmotropism. 

A similar process takes place where plants use adhesive pads to adhere to objects such as walls. Eg Parthenocissus spp. 

Negative thigmotropism is demonstrated where plant roots grow around solid objects in the soil as they grow under the influence of geotropism.  


To grow and survive plants rely on water moving from roots to the other parts of the plant. Transpiration is the process of water movement and subsequent evaporation of water from the plant parts designed for this.

Only a small amount of water taken up by the roots is used for metabolism and growth, the remainder is voided through the stomata and evaporates.

Trickle irrigation (Drip Irrigation)

A form of irrigation often found in horticulture. A simple example would be soaker hoses. When growing commercially I used drip irrigation, which provided a gentle trickle of water to tomato, pepper and cucumber plants via a drip nozzle. In orchards, a similar form of drip or trickle irrigation is often used to irrigate trees. 

As with most forms of irrigation, trickle can be controlled by a computer that may be programmed to irrigated at preset times or when a moisture meter determines need. The computer may also adjust the amount of water given based on the amount of sunlight or other factors. 


The response of a plant to an external stimulus. 

Phototropism, geotropism, heliotropism, chemotropism, thermotropism, hydrotropism, thigmotropism, halotropism and electrotropism are all plant tropisms. 


A storage organ found in many plant species. Eg the potato is an underground tuber used as a means of asexual reproduction.  In the case of the potato the tuber is a stem tuber (not root as many suppose).  Some tubers are derived from modified lateral roots eg dahlias and sweet potatoes. 

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Gardening Terminology – U


A botanical word meaning a cluster of flowers where the stalks spring from a common centre, are of similar length and result in a flat or slightly convex surface. An example would be the carrot flower.

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Gardening Terminology – V


An organism capable of transmitting an infectious agent. 


Vermiculite is produced by heating mica until it expands. Heating produces a light spongy material that is able to hold air and water in composts. 

Vertical Growing

Vertical growing is where the plants grow, or are arranged, vertically.

At a basic level, this includes cordon and espalier fruit such as tomatoes, cucumbers and runner beans to apples and pears.

Vertical growing also includes where a series of pots or containers are stacked above one another in a vertical plane. Eg using pot holders affixed to a wall.

Vertical growing can also include green walls etc. This is usually achieved using hydroponics.


A genus of fungi, some of which cause verticillium wilt in plants. 


Plant viruses cause a wide range of problems. It has been argued for a long time that a virus is not actually alive as it is only able to reproduce within a host (the plant in this case).  

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Gardening Terminology – W

Wardian Case

The Wardian case is named after Victorian plant explorer Dr Nathaniel Ward who wanted a container in which he could transport his specimens back to England. Plants in pots travelling in the holds of ships died due to a lack of light and, on deck, they suffered salt spray and adverse weather conditions.

So in around 1829 Ward designed an airtight glass case in which plants could travel. It’s a similar concept to bottle gardens or terrariums. There is some evidence that similar containers had been in use prior to Wards invention!


Waterlogged soils are those that are completely saturated with water. They therefore lack air and most plants will die in a few days without air. Waterlogging can be temporary or permanent. 


A plant growing in the wrong place. Eg a potato growing in a lawn is as much as a weed as a thistle in the lawn! 


Plants are said to go woody when the stem starts to harden and grow bark

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Gardening Terminology – X


Xeriscaping is a water conservation process where landscapes are designed that use minimal or no irrigation. The landscapes and plants in it survive on natural rainfall. It’s therefore more appropriate to landscaped amenity and ornamental gardens as many veg need watering when the crop is getting established or bulking up.

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Gardening Terminology – Y


Yellowing of leaves is often indicative of a number of fungal and viral problems. Eg. Fusarium Patch in lawns and Fusarium Wilt in tomatoes.

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Gardening Terminology – Z


The dispersal of plant seeds and fruit by animals such as ants, bats, birds, monkeys etc. This is viable seeds that become attached to fur, feathers etc, or in the digestive system etc.

Examples include cherry stones spread by birds and even tomatoes spread by humans!


Zygomorphic flowers are where there is one plane of symmetry meaning it’s bilaterally symmetrical. Ie symmetrical side to side such as peas, salvias and penstemons rather than being like a daisy where a line of symmetry can be drawn through the centre of the flower at any point.  

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