A seed is nature's way of storing young plants, transporting them and bringing them to life in correct conditions. Moisture begins the process of germination.
Soaking seed for 24 hours before sowing helps germination but always water the compost immediately before or after the seed is sown. The compost must stay moist throughout the germination period.
Temperature
As well as moisture, seeds need a consistent temperature. The average temperature is around 21°C, but tropical seed may need more heat. An airing cupboard is the ideal place for seeds which do not need light to germinate. Oxygen is also vital, combining with the seed's food store to encourage growth.
Sowing dust-sized seed
Some seed needs light to make it germinate. The finer the seed, the more likely it is to need exposure to the light.
• Water the compost before sowing surface-growing seed. If you water from the top after sowing, the seed is likely to be washed out of the compost.
• Sow such seed on the surface of the soil and gently press it against the compost. Do not cover the seed with compost. Just be sure that the two make contact so the seed can absorb moisture. -After sowing, cover the container with a sheet of glass or clear plastic sheeting. This ensures that moisture remains in the container and keeps the temperature even.
• Place the container in a well-lit spot but not in direct sunlight. Beads of moisture will form on the inside surface of the glass or plastic and fall back on to the compost to keep it slightly damp.
• Sometimes the surface of the compost looks moist while underneath it is drying out. Feel the compost regularly to check that it is moist under the surface. If it appears dry, water from underneath. If the compost dries out for any length of time the seed may not germinate.
TIP HOW TO WATER
Before sowing, and until the seedlings appear, water the compost from underneath.
• Fill a sink to a depth of 2.5cm with tepid water and stand the pot or tray in the water.
• When the compost is thoroughly damp, beads of moisture will appear on the surface.
• Remove the container from the water and leave it to drain.
Sowing larger seed
Larger seeds do not need light to germinate.
• Cover the seeds with a thin layer of compost. The best way to do this is by sifting the compost lightly and evenly through a fine sieve. Crumbling compost by hand rarely achieves a fine texture: some seeds are covered by too much compost which prevents them from germinating.
• Cover the container with a sheet of glass or clear plastic followed by a sheet of newspaper to keep out bright light.
• Check the container regularly to see if the seedlings have germinated. As soon as the seedlings appear, remove the glass and paper and place in a good light but not hot, direct sunlight. If you leave seedlings in the dark after they have germinated, growth is weak and spindly. Such seedlings will not make good adult plants.
SOWING HINTS
Cover seed with the same depth of compost as the seed's diameter. Mix dust-like seeds with fine silver sand to mark where they are sown and to give a better chance of sowing them evenly.
When transferring the seedlings, select only the strongest ones. Use a 'dibber' or a pencil to make the planting hole.
IMPORTANT
Plants release their seeds in various ways. Some, like the maple, enclose the seed in winged cases which are blown by the wind, considerable distances from the parent tree. The seed heads of other plants explode in the air, scattering some seeds in the immediate area, others to be blown further by the wind. Birds also play a part by eating berries and excreting their undigested seeds far and wide.
Seeds have either soft or hard coats. You can encourage hard coated seed to germinate by gently scraping or chipping the seed's surface to let moisture in.