A simple method of sterilising the compost is to water it with Cheshunt Compound steriliser. This chemical can be obtained from any seed store. It consists of a powder which, when dissolved in water, is sprinkled over the compost before or after the seeds have been sown.
It is perfectly safe to use, and does not injure the smallest seedlings. Seed boxes and pots can be sterilised by this method and thereby made pest free. A satisfactory seed compost may be obtained by sterilising the loam only, and then adding the peat, sand and fertiliser.
The soil ingredients are sifted through a sieve having a mch mesh and thoroughly mixed. The pots or best seedbox are given plenty of drainage crocks which are covered with rough siftings from the compost, and the receptacles are then filled with the compost.
This is made moderately firm by pressing it with the fingers; it is then moistened by holding the receptacle in a pail of water.The water must not come above the rim of the pot because it is necessary that the moisture should rise up through the compost. As soon as the surface of the soil becomes damp, the pot is set aside to drain for a few hours before seed sowing is commenced.
The depth to which the cheap seedbox are covered depends on their size. Very fine seeds, such as those of Begonia, require only a fine sprinkling of silver sand, whereas larger seeds should be covered to the depth of their greatest dimensions. When the seeds have been sown, the receptacles should be covered with panes of glass and shaded with sheets of paper.
Each day the glass should be reversed to prevent the condensed moisture from dripping on to the soil, and setting up decay. As soon as the seedlings appear, however, the paper covering must he removed and ventilation of the receptacle begun. The glass covering should therefore be tilted slightly. This is conveniently done by means of the plant label, and the amount of air is increased in this way until the covering can be removed altogether.
As soon as the seedlings have developed their first true leaves they are pricked apart in pots of fertile compost such as John Innes Potting Mixture and immediately watered in.To prevent green scum (algae) forming in the water, it is best to place a few small lumps of charcoal in it. If this operation is done in the spring, the bottles of ‘cuttings’ can be set on the window-sill, and roots will form in a few weeks. Potting must be done immediately roots begin to form.