This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
All the garden Crotons are descended from C. variegatum (also called C. pictum), a native of the Molucca Islands, but now more or less naturalized all over the eastern tropics. The original species is an evergreen shrub, having leaves 2 to 10 in. long, varying from oblong to very narrow, often wavy and variegated with green, yellow, red, crimson, etc. Owing to the ease with which the small flowers can be cross-fertilized, numerous garden hybrids have been raised, and constitute a very valuable group of commercial decorative-leaved plants.
Crotons require plenty of heat and moisture and a fair amount of sunshine to develop the rich colours of the foliage. Plants may be grown in all sizes of pots from 3 in. up to 10 in. and 12 in., but the most popular size for market is that grown in 5-in. pots (48's). The leaves are highly valued in the florist trade, being largely used for backing up the flowers in wreaths, crosses, etc, and for intermingling with effect in bouquets of various descriptions. The broad-leaved varieties (fig. 274) are appreciated for some kinds of work, while the narrow-leaved sorts (fig. 275) are favoured for other purposes; and the trade is not a fleeting one, but lasts the whole year round. The prices obtained for foliage vary from 9d. to 1s.6d.per bunch; while plants realize anything from 1s. 6d. to 3s. 6d. each in 5-in. pots.
Crotons flourish in good fibrous loamy soil, with a dash of leaf mould or well-rotted manure, to which a little basic slag may be added. The plants should have a minimum winter temperature of 65° to 70° F. During the spring, summer, and autumn months the atmosphere should be kept humid yet buoyant, and during rapid growth copious supplies of water are given, and also numerous syringings. The main point is to keep the plants growing rapidly, and if fairly well exposed to the sunshine they will develop fine colour and be harder in texture.
To secure nice shapely plants on single stems, cuttings of fairly well-ripened shoots will root freely in late summer or early autumn in a gritty compost or in leaf mould, coconut fibre, etc, and with a bottom heat of about 80° F. Large pieces with several shoots will also root freely, and in this way quite large plants are obtainable in a comparatively short time. When well rooted they are potted up and grown on.
Fig. 274. - Codiaeum (broad-leaved).
Fig. 275. - Codiaeum (narrow-leaved ).
Mealy Bug, Scale, and Red Spider are the worst enemies of the Croton, but they can be kept in check by frequent syringings with warm or at least tepid water, to which may be added some well-known quassia and nicotine insecticide. Fumigating and vaporizing are also useful in keeping these pests down, as well as Thrips, which are sometimes troublesome.
The following are amongst the best kinds of Crotons grown: -
Andreanum, Williamsi, Thompsoni, Reidi, etc.
Angustifolium, Aigburthense, Johannis, picturatum, Warreni, aneitense, Weismanni, Mrs. Dorman, ruberrimum, majesticum.
Disraeli, Earl of Derby, Evansianum, illustris, F. K. Sander.
Chelsoni, caudatura tortile, spirale, Prince of Wales, etc.
Queen Victoria, Sunset, undulatum, Sunrise, Flambeau, recurvifolium, volutum, Van CErstedi, Flamingo, Hawkeri, etc.