This section is from the book "The Florists' Manual", by William Scott. Also available from Amazon: The Florist's Manual.
You can walk through many a greenhouse establishment, large and small, without seeing a specimen of any of these curious plants, and unless you are a specialist you will be wise to leave them alone. The demand for them is altogether too small. You will, however, be often asked: "How shall 1 make my cactus flower?" etc., and as the florist is supposed to know how to cultivate every green thing, it is well to be able to give an intelligent answer to the old lady whose uncle sent her the cactus in question many years ago from Mexico.
Grotesque and peculiar as the growth of many of the cacti is, the flowers of some, notably the night blooming cereus (C. grandiflorus) are most gorgeous. It lasts but one short night, but while open it is almost unrivaled in its magnificent form, lovely colors, the beauty of its stamens and general appearance, as well as great fragrance.
The mammillarias are the most useful for bedding, making a beautiful appearance in a bed of succulents. The United States and Mexican species will winter in a very cool place and need little if any water in the dark winter days. All of the tropical kinds will winter very well in a night temperature of 55 degrees, and our summers suit them well.
They are about as easily grown in a window as they are in the greenhouse if proper care is used in watering. Few if any insects trouble them. Drainage is of first importance, and neither in summer, when they are growing, nor in winter, when they are at rest, should the soil ever remain saturated. So, whatever the compost be, let the pot or tub be filled one-third with broken crocks, so that water is sure to pass off quickly. In winter, when little growth is being made, especially if you are keeping the plants cool, water sufficient to Keep the soil from getting dust dry will do. In April and May and through the summer, if the soil is well drained you can water daily.
The soil should be a good fibrous loam, to which add one-fourth of coarse sand, and if that is not at hand add some powdered bricks or old plaster crumbled up. They need little pot room and should not be shifted for several seasons. All of them would do well out of doors in summer time if convenient to put them outside, but look out for heavy rains; for those that are in pots or tubs too much water will rot the roots.
Some of the genera are hardy in the latitude of New York, but a very severe winter will hurt them, and where used for bedding it is better to lift them and place in flats and winter in a cold house or protected frame.
The most valuable of the cacti grown for their flowers, and which makes a most showy winter flowering plant, is Epiphyllum truncatum and its varieties. It does not make a good plant on its own roots, not being strong enough to stand erect, and when a handsome little tree is seen it has been grafted on the pereskia stock. The flowers of the epi-phyllum are most numerous and its varieties have colors varying from deep scarlet to almost pure white. The type is a deep rose color.
Like all the cacti, the epiphyllum wants perfect drainage and must not be overpotted. Keep cool in the late fall months till they begin to show flower, when they should have more heat till the flowers are fully expanded, and can then be removed to a cool house, which will prolong the life of the flowers.
The operation of grafting the epiphyllum on the pereskia is very simple. Pieces of the pereskia of any desired length will root in moderately moist sand. When potted off and established in pots the top of the stem is split for an inch or so, a branch of the epiphyllum inserted, and nothing more is done except to tie a piece of raffia around the stem to keep the graft in place, and this must be removed as soon as adhesion takes place, which will be soon if the plants are kept in a warm, moist house.