Glossary of Terms

Below is an alphabetical list of some of the more commonly used terms in gardening that you may come across.

Aeration – commonly refers to either the puncturing of the soil with spikes (spike aeration) or removing of soil from the ground (core aeration). Aeration may be overlooked when trying to restore a lawn but it improves drainage and reduces the formation of puddles.

Digging over soil prior to sowing vegetable seeds will break up the soil creating larger air pockets and so aerating the soil.

AGM – Award of Garden Merit. An accolade given by the RHS when varieties have performed particularly well in trials. Whilst these varieties tend to retain the award, the RHS have started to withdraw it when they feel that the quality has slipped.

Bolt – The name for when vegetables flower. It is usually caused by poor soil or if the plant gets dry at the root. This triggers a survival reflex in the plant which causes it to flower and set seed rather than continue to develop.

Brassicas – The leafy family of vegetables that include Broccoli, Brussels Sprouts, Cabbage, Cauliflower and Kale.

Cloche – Traditionally bell shaped but, more commonly now, a miniature tunnel, usually of plastic, that is used to protect your crops during cooler conditions.

Cold frame – Essentially a mini, unheated greenhouse. Cold frames are usually built low to the ground and have a transparent, hinged top.

Cotyledons – The technical term for the seed leaves or the leaves which are the first to appear after germination.

Curds – The heads of a cauliflower.

Cut and come again – Referring to leafy salad plants – usually lettuce – that can be cut several times for salad leaves.

Direct sowing – Some crops need a little care and attention before they are planted outside and can be started in pots or trays. However, quite a number of vegetables can be sown directly into the soil outside where you want them to grow – this is known as Direct sow.

Dormant – Used to describe the state of a seed that is not dead. Seeds can remain dormant for several years if stored correctly and just require the correct combination of temperature and moisture to kick start the germination process.

Drills – The term used to describe the shallow indentations or furrows that you sow seed into. They are usually straight when sowing vegetables for ease but, in some cases, they can be shaped.

F1 – If you see this after the variety, the plant has been produced by crossing two carefully selected parent plants of the same species. These have usually been developed over a number of generations through self-fertilisation to produce more uniform and vigorous varieties than normal open-pollinated types. They are usually more expensive due to the complex processes involved and seed saved from an F1 variety will not reproduce the uniformity of the original.

F2 – This is used to refer to an F1 hybrid that has either self-fertilised or has been crossed with another F1 Hybrid. These can retain some, though not all, of the attributes of the F1 parent(s) and are generally cheaper.

Frost hardy – Plants that are able to tolerate outdoor conditions at all times of the year.

Germination – This is the process whereby the seed starts to grow from its previous dormant state.

Harden off – Plants that have been started off indoors or in a heated greenhouse will not be ready to plant out immediately. They need to be acclimatised to outside conditions and should be placed outside for a number of days after the last frosts then brought in each night. This process is known as hardening off as it is designed to toughen up the young plants.

Leggy seedlings – If a seedling is not getting enough light, it will accelerate its growth towards whatever light it can get in an attempt to be closer to it. Unfortunately, there is only a certain amount of growing that it can do and the result will be ‘leggy’ seedlings – they will be tall but have no strength in the stem and, as a consequence, they will tend to droop or even fall over.

pH – In simple terms, pH is the measurement that ascertains whether something is acidic or alkaline. A number below 7 indicates acidic and over 7 is alkaline while 7 is regarded as neutral. Some plants are tolerant of acidic conditions whilst others are not. If a plant requires specific pH levels, it will be noted on the seed packet.

Pollination - the process of reproduction in plants where pollen is transferred between them.

Pot On – As seedlings grow, they can become too big for the trays or pots that they were sown in but it may be too early for them to be planted out. In these cases, they need to be ‘potted on’ to larger trays or pots that will allow their roots to grow and thrive making the plant stronger.

Pricking out – The stage before ‘potting on’. When seedlings have produced their first set of leaves, they will usually be quite crowded in their trays. At this point they will need to ‘pricked out’ into individual modules or in groups of four or five to a pot.

Propagator – In simple terms, this is a miniature greenhouse. It generally consists of a plastic base (usually black or green) with a snug fitting, clear plastic lid. The lid often comes with adjustable vents to ensure that the plants don’t get too hot. For a larger investment, you can get heated propagators that include heating pads that will create the perfect environment for most plants that you want to grow.

Rootrainers – A special form of cells for seedlings that encourages deeper root growth than standard trays or cells.

Roots – The roots of a plant serve a dual purpose. Not only do they attach the plants firmly within the soil or to a support, they also convey water and nutrients to the rest of the plant.

Seed – A seed is an incredible feat of packaging. Something that can be as small as a pin head contains a small plant in embryo form, complete with a food store and all protected by a tough outer skin. When seeds are kept dry and in cool conditions, seeds can remain dormant (but alive) for several years. When these miniature plants factories are exposed to favourable conditions – usually a combination of the correct temperature in the soil and the right level of moisture – they start to take on water. This process causes the seed to swell until the outer protective skin bursts and the embryonic plant can then start growing.

Seedbed – When sowing or transplanting instructions suggest the use of a seedbed, this is simply referring to an area that has been carefully prepared to give your young plants the best chance of developing. It often incorporated a cold frame and is sometimes a raised bed. These options give the plants a chance outside whilst protecting them somewhat.

Seedling – A young plant usually raised from seed rather than a cutting.

Sharp sand – Also known as coarse sand. A general purpose sand sometimes used for top dressing a lawn.

Sunscorch – Damage to leaves from too much direct sunlight. Often caused when seedlings and plants are covered with glass or plastic for too long and particularly if the leaves touch that cover during particularly sunny days.

Thinning out – However careful you are when sowing your seeds, as the seedlings grow, they will often need more space to fully develop. Taking out some of these seedlings to give the others more space is known as thinning out. The seedlings that are removed are known as thinnings and, if your space allows, can be replanted elsewhere.

Tilth – is a term used to describe the condition of soil that has been prepared – usually for seeding. A ‘fine tilth’ is a finely prepared soil.

Transplant – To move a plant from one growing position to another.

Vermiculite – A mineral that is used to aerate the soil (see aeration above) and has some water holding capacity that aids rewetting.

Viable – A viable seed is simply a seed that will grow i.e. a living or dormant seed.