This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
As a decorative plant either for house or greenhouse, or for cutting from, few plants can surpass the Cineraria. The variety and colours of the best strains of it are very beautiful, and as the time and labour expended in the cultivation of them must be the same, whether the plants turn out to be good varieties or otherwise, it is worth taking some pains to secure a good strain. For general decorative work it is best to raise the plant from seed, as there is less trouble with them, and they almost always show the largest heads of bloom. In order to have a succession of flowers, a pinch of seed should be sown twice in the year. The first sowing should be made early in February in a well-drained pan. Sow the seed thinly, and cover with a piece of glass in order to afford the necessary shade and closeness, until the seed begins to vegetate. Allow a little air as soon as it is well brairded, so as to harden the young seedlings. As soon as they are large enough to handle, prick them out singly into thumb-pots, and plunge them in a box of leaf-mould, sawdust, or cocoa-nut fibre, in order to keep them at a proper degree of moisture and to save repeated waterings.
They must be kept at this stage in a temperature of from 55° to 60°. In the course of a few weeks they will require shifting into larger pots, which may be 48's, or 4-inch pots. The compost should consist of good fibry loam and leaf-mould in equal parts, with sufficient sand to keep all open. They must still be kept in a temperature of not less than 50°, and aired on every favourable opportunity; also kept as near the glass as may be convenient; and an occasional dewing with the syringe will refresh them very much. In the course of six weeks or so, if all has gone well, they will require another shift, this time into the pots they are meant to bloom in, which for ordinary work may be 6-inch or 7-inch pots, unless large specimen plants are desired, when larger pots may be used, or better still, give another shift later on. With due care and judicious feeding, however, almost as good plants may be produced in a 7- or 8-inch pot as in those much larger; and from being more manageable, the smaller sizes are the more desirable.
The soil should be a little stronger for this shift, using less leaf-mould, and enrich with some old cow-dung, or a pinch of bone-meal. About the beginning of June the plants should be set in a cold frame or pit, where abundance of air can be given; or if in a frame, a current of air should be allowed to play among the plants, by tilting up the frame and putting a brick under each corner. It may be necessary to shade them slightly for a few hours in the middle of the day, and give a dewing with the syringe in the evenings. Keep a strict watch for green-fly, the great pest of Cinerarias, and fumigate with tobacco-smoke on its first appearance. Some kinds of Cineraria are more subject to the attacks of green-fly than others. The variety we grow has smooth shiny leaves, not so woolly as some kinds we have seen, and unless through neglect in watering, are seldom troubled with green-fly. There is another form of disease which they are subject to sometimes - viz., the sap exuding from the upper surface of the leaves and stems, and drying in globules, so that the plants look as if they had been sprinkled over with white sand.
We cannot tell the cause of this, as we have seen it on plants to all appearance in vigorous health, unless it may have been through the plants having been subjected to too bright sunshine. When the plants have filled their flowering pots with roots, and begin to throw up the flower-spikes, then they may have an occasional watering with liquid manure, say about twice a-week.
A second sowing should be made in the first week of June and treated much in the same way, only that as soon as they have been pricked out and established in their small pots, they may be grown on in a cold frame or pit, and shifted as they require it; but as they are to stand over the winter we would not advise larger pots to be used than 6-inch. The first batch of plants will come into bloom in the autumn, the second in spring. By shifting on a few at a time, or by sowing oftener, a succession of bloom may be had all the year over. Where distinct varieties are desired for exhibition or otherwise, they must be propagated by offsets from the old plants. To get these, the plants, as soon as they have done flowering, should be planted out in rich soil until they throw out shoots round the neck of the plants. A sufficient number of these should be slipped off with a heel, and potted up singly, plunged and shaded till they are rooted, after which they may be subjected to much about the same treatment as described above for seedlings. They never make such strong robust plants as those raised from seed, and consequently will not as a rule require so much pot-room. In the majority of cases, 6-inch pots will be quite large enough to flower them in.
There should always in any case be a proportion of plants allowed to flower in 4- or 5-inch pots. These come in very handy sometimes for filling vases, or room decoration, where larger pots are not suitable; and we have seen wonderfully fine heads of bloom produced from pots of this size. There is one fact worth remembering in regard to Cinerarias raised from seed, and the same may apply to other subjects as well, and that is, that it is generally the self-coloured flowers which vegetate first and grow strongest in the seed-pan; therefore one should not be in a hurry in throwing away the remainder after pricking out a lot, but also take some of the later-brairded seeds. This has never been more forcibly brought before us than this year, when, out of a large number of plants grown, almost without exception they turned out self-coloured flowers, though many varieties in shades of colour. The seed was saved by ourselves, and all from parti-coloured flowers; the reason being that we took the first of the seedlings ourselves, and a party who got some of the later plants had a large proportion of fancy flowers.
J. G. W.