Growing plants - Glossary

Capillary bed:

a bed, usually of gravel, for germinating punnets of seeds. Water is fed in continuously from the bottom and kept at a constant level. Heating may be provided. Replaces overhead watering which can lead to damping off (a fungal disease) or can disturb the surface of the seed mix. For diagram see Figure 1.

Clone:

plants which have been propagated from cuttings or by layering (i.e. vegetatively) have an identical genetic make-up to parent plant. They are called clones.

Cotyledon:

a leaf-forming part of the embryo of a seed plant. Monocotyledons have one and dicotyledons have two cotyledons in each seed.

Damping off:

a fungal disease which attacks young seedlings at ground level causing them to rot and fall over. Overcrowding of seedlings and poor drainage of seed mix are common causes. Destroy seedlings as soon as detected.

Hardening off:

the gradual process of conditioning plants to the garden climate. A shaded area or a shady, wind-protected position in the garden is used to acclimatise the young plants for a week or two, then a further three days of exposed hardening off is recommended prior to planting out.

Hormone:

a substance which can be transported through an organism and can affect growth, reproduction or metabolism (rate at which food is converted into part of the living thing). Certain synthetic hormones can be applied to cuttings to encourage quick root formation. They are particularly useful for slow rooting species. Hormones must be used with great care.

Layering:

a method of vegetative propagation where stems are partially cut and either wrapped in coconut fibre or pegged down under soil until they root. Rooted pieces are then cut from the parent plant and potted up.

Simple Layering

layering rooting

Steps involved in aerial layering

layering

Parent plant:

plant from which cutting material for propagation is collected.

Peat:

brown decomposed plant matter found in some swampy areas. It has a high water holding capacity and was once widely used in potting mixes and cutting mixes. The extraction of peat is having a damaging effect on the ecosystems from which it is taken and its use is not recommended for this reason. It is now frequently replaced by substitutes such as composted woodchip fines, coconut fibres or rice hulls.

Potting on:

this is the process of transferring rooted cuttings from the cutting mix into pots of potting mix for growth before hardening off. Potting on enables the plant to establish a good root system.

Pre-treatment:

one method of pre-treatment involves lightly damaging the seed coat to allow water uptake necessary for germination. Usually heat or abrasion (rubbing the seed coat with sandpaper) are used - e.g. with Acacia seeds. Pre-treatment for seeds of some plants involves chilling seeds (cold, moist stratification).

Pricking out:

the process of transferring seedlings from the seed mix into pots of potting mix for growth before hardening off and planting out.

Semi-hardwood:

last season's growth which has hardened off. This growth is ready for preparing cuttings if it does not break when bent in half.

Sphagnum moss:

a type of moss which retains moisture well and is sometimes used in propagation such as in aerial layering. Its use is not recommended, as serious damage is caused during its extraction from the fragile areas in which it grows.