Glossary of Gardening

Glossary of Gardening Terms: A to C

We realise it can get a little confusing sometimes trying to decipher grow guide instructions, botanical research papers and other publications relying heavily on horticultural terminology, so here’s the first part of a guide to the botanical basics, with our A-Z glossary of gardening.

An A-Z Glossary of Gardening: A to C | D to H | I to P | Q to Z


An A-Z Glossary of Gardening: A to C

Gardening Glossary – A

Acidic – A compost, liquid or soil with a pH level of between 0 and 7.0 (the scale runs until 14.0). Sometimes referred to as “sour” soil.

Aeration – Any method of loosening soil or roots with the aim of improving air circulation.

Aerobic – Refers to organisms which can exist only in the presence of oxygen.

Aeroponics – The art of growing plants without soil, by suspending them in air and misting the roots.

Alkaline – A compost, liquid or soil with a pH level of between 7.0 and 14. Sometimes called “sweet” soil.

All-purpose fertiliser – Fertiliser with an equally-balanced ratio of N-P-K (Nitrogen-Phosphorous-Potassium).

Amendment – Soil improvement by means of the addition of mineral or organic substances.

Anaerobic – Refers to organisms which can exist only in where oxygen is not present.

Annual – Plants which live for a year, during which they germinate, flower, seed and then die.

Auxin – Auxins are plant hormones which are responsible for foliage and root elongation.

Gardening Glossary – B

Bacteria – Microscopic, one-celled organisms.

Beneficial insect – Any insect which helps to control pest species, usually by eating or laying their eggs in them.

Biennial – A plant which completes its life-cycle in two growing seasons – producing leaves in the first, flowers in the second.

Biodegradeable – A (normally organic) material which can break down or decompose by means of natural bacterial or fungal action.

Biological pest control – The use of living organisms (such as beneficial insects) to destroy garden pests.

Bolt – A plant which has prematurely set seed.

Bone meal – A white or light-grey, phosphorous-rich fertiliser made from finely-powdered bone.

Bonsai – A plant growing as an unnaturally short or dwarfed form.

Breaking bud – A growth stage when buds break free from their protective scales.

Breathe – Referring to either roots drawing in oxygen or stomata drawing in carbon dioxide.

Broadcast sowing – Evenly scattering seeds over the ground’s surface.

Bud blight – A condition which causes flower buds to wither.

Buffering – Using a substance to minimise shock by cushioning a plant against fluctuations in pH.

Bulbs – A short stem with fleshy leaves or leaf bases, used to store food during dormancy (e.g. daffodil and tulip bulbs).

Gardening Glossary – C

Calcitic limestone – A substance containing calcium carbonate, which is often used to “lime” soil, reducing its pH.

Calyx – A plant’s pod or seed pod, containing the female ovule and two protruding pistils.

Carbohydrate – A neutral compound comprising carbon, hydrogen and oxygen (such as cellulose, starch and sugar).

Carbon dioxide (CO2) – A colourless, odourless and tasteless gas essential for plant life and increased biomass.

Caustic – A substance with the property of destroying, eating away or otherwise killing via chemical activity.

Cell – The base structural unit that plants (and all living things) are built from.

Cellulose – A complex carbohydrate that strengthens and stiffens plant tissue.

CFM – Cubic Feet per Minute.

Chelate – A combination of nutrients in one atomic ring, making it easier for plants to absorb. Often used in commercial fertilisers, soluble chelates help to keep nutrient metals, such as iron, mobile in the soil, rather than locked up in insoluble mineral salts.

Chlorine – A toxic but useful chemical used to purify water.

Chlorophyll – Essential to the production of carbohydrates via plant photosynthesis, this gives plants their green colour.

Chloroplast – Containing chlorophyll.

Chlorosis – A sickly blanching or yellowing of leaves caused by a lack of chlorophyll, disease or nutrient deficiency.

Clay – A soil formed of extremely fine particles of organic minerals.

Climate – The average condition of the weather.

Cold Frame – An unheated structure used to extend the growing season by protecting plants from frost. Normally made of wood and covered with transparent glass or plastic.

Colour spectrum – The colour band emitted by a light source. Measured in nm.

Colour temperature – The relative whiteness of tungsten steel when heated to that temperature in degrees Kelvin.

Colour tracer – A coloured substance present in many commercial fertilisers, enabling gardeners to easily see if they’re part of a particular solution.

Compaction – A soil condition resulting from soil being packed down too tightly, which causes problems with aeration and root development.

Companion planting – Planting complimentary plants together, encouraging cooperative growth by choosing chemically-compatible and non-competitive species.

Compost – A rich, dark mix of decayed organic matter which is used to improve soil fertility.

Contact weedkiller – A powerful chemical weedkiller which kills when applied directly.

Corms, rhizomes and tubers – Dormant stems, such as dahlias or irises, which are normally planted in autumn for spring flowering.

Cotyledon – The part of a seed which stores the energy used to nourish the plant until its first true leaves are established.

Cover Crop – Vegetation planted to protect and improve the soil when it would otherwise lie fallow.

Crop Rotation – The planting of a particular crop on an alternative site from that used over the previous year.

Cross-pollinate – Attempting to create a hybrid by the pollination of two plants with different ancestry.

Cubic foot – A unit for measuring volume under the Imperial and American systems – Length x Width x Height = CuFt.

Cutting – Referring to a piece of bud, leaf, root or stem taken from an existing plant to be rooted separately.


An A-Z Glossary of Gardening: A to C | D to H | I to P | Q to Z