Glossary
A plain-English gardening glossary
Short, clear definitions of the gardening and horticulture terms you will meet in our guides and category overviews — and in seed packets and plant labels everywhere.
A
- Annual
- A plant that completes its whole life cycle — germinating, flowering, setting seed and dying — within a single growing season.
B
- Bare-root
- A dormant plant lifted and sold without soil around its roots, planted in the cool season. Common for trees, roses and hedging.
- Biennial
- A plant that grows leaves in its first year and flowers, seeds and dies in its second.
C
- Cloche
- A portable, often transparent cover placed over plants or rows to warm the soil and protect against cold, wind and pests.
- Cold frame
- A low, lidded box with a transparent top, used to harden off seedlings and raise early crops.
- Compost
- Decomposed organic matter used to improve soil; also a bagged growing medium for containers and sowing.
D
- Deadheading
- Removing spent flowers to tidy a plant and encourage further blooming rather than seed production.
G
- Germination
- The point at which a seed begins to grow, sending out a root and shoot.
H
- Hardening off
- Gradually acclimatising indoor-raised plants to outdoor conditions over one to two weeks before planting out.
- Humus
- The stable, dark organic fraction of soil left after organic matter has fully broken down; it holds nutrients and moisture.
L
- Loam
- A balanced soil of sand, silt and clay that drains freely yet holds moisture and nutrients — the texture most gardeners aim for.
M
- Mulch
- A layer of material spread on the soil surface to retain moisture, suppress weeds and, if organic, feed the soil as it breaks down.
N
- No-dig
- A method of gardening that avoids turning the soil, instead feeding it with an annual surface mulch of compost.
P
- Perennial
- A plant that lives for several years, usually flowering each season once established.
- pH
- A measure of how acidic or alkaline the soil is, from 0 to 14; most garden plants prefer a slightly acidic to neutral range.
- Pricking out
- Transferring tiny seedlings from a sowing tray into individual cells or pots to give them room to grow.
T
- Tilth
- A fine, crumbly surface layer of soil prepared for sowing seed.
- Tender
- A plant that cannot tolerate frost and needs protection or a warm season to survive.