The principal house plants which are easy to raise by sowing seeds are Aloe (succulent plant Asparagus species, Begonia semper-florensundB. rex, cacti (many kinds Clivia, Cyclamen, Eucalyptus, Fuchsia (varieties Grevillea robusta, Opuntia, Passijiora, Phoenix (palm Primula malacoides and P. obconica, Ricinus, Rochea (succulent plant Saintpaulia (hybrids) and Solatium capsicastrum.
The most suitable compost
It is best to sterilise the compost, and it should therefore be heated in a sterilising apparatus for 10 minutes at a temperature of 18o? F. After this partial sterilisation, the compost must be spread out on a bench to cool before use.
Watering a seed pan by partial immersion
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.
Preparing the seed compost
The soil ingredients are sifted through a sieve having a |-mch mesh and thoroughly mixed. The pots or seed pans 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 seeds 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.
Pricking out the seedlings
As soon as the seedlings have developed their first true leaves they are pricked out ? inch apart in pots of fertile compost such as John Innes Potting Mixture No. 1, and immediately watered in. They are shaded from bright sunlight until they are established. This generally takes 7-14 days, after which they are given more light and air. The “cuttings” are taken in the usual way, by severing them just below a node (where a leaf is inserted in the stem). They are then fixed in the mouths of small-necked bottles where they remain suspended. The bottles are filled to within a fraction of an inch of the top of the necks with water, preferably rain water.
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.