This section is from the book "The Florists' Manual", by William Scott. Also available from Amazon: The Florist's Manual.
This useful climber and twiner seems to have been grown here commercially long before its great usefulness was appreciated in Europe. Though the more graceful looking asparagus has superseded it in our decorations it is still a standard article with all commercial florists, and in funeral decorations there is no equal to it.
One author says it is propagated by "seeds, cuttings and divisions." I have never heard of its being rooted from cuttings, and to divide it would be absurd, as it is so easily raised from seed.
Seed should be sown in flats and covered an eighth of an inch, in February. Good fresh seed is now always supplied. When two or three inches high, pot off into 2-ineh pots and keep in a temperature anywhere above 50 degrees. If you expect the best results from your newly planted bed you ought by the middle of May to give these little plants another shift into a 3-inch. Getting strong plants to plant out in June will give you an extra crop over small, weak plants. And although you often see them standing under a bench in May and June, that is not the way to produce well rooted, strong plants.
Make your smilax bed in the center of the house on the ground with seven or eight feet of head-room; more is better. If the floor of the house is naturally dry you want no preparation, but make the bed seven or eight inches above the surface and confined with a brick or plank wall.
I have tried several kinds of soil. The worst smilax I ever grew was in a light sand, and the best was in a stiff loam, such a soil as roses like, with the addition of one-fourth of rotten cow manure. Plant at the end of June or very early in July.
If you intend to renew the bed every year, which I strongly advocate, then plant ten inches between the rows and six or seven inches between the plants. Run a wire across the bed just behind the row of plants, and a corresponding wire near the roof, and at each plant run up a string of silkaline. It is invisible when cut and saves you much bother when using the smilax because there is no need of pulling it out.
Keep down weeds from the start and frequently teach the little growths that they are to climb up the strings. When once started they are no trouble, and when a crop is cut and a new growth is starting replace the strings at once. We are guilty of neglect and I have seen days of labor spent over a smilax bed that was allowed to grow without strings a few weeks and had to be unravelled and started up the strings, much to the harm of the growths.
When growing fast smilax likes and must have an abundance of water and should be daily syringed to keep down red spider. It should also be fumigated, but not heavily or it will turn the tips of the leaves. Vaporizing with tobacco extract would avoid that, but with proper care we have no trouble with the smoke.
When a crop is fit to cut or your business demands that you cut it, begin at one end and clear it as you go. When the plant is denuded of its entire growth, as it is when you cut the strings, it does not want water till it begins to send up more growth. I have seen the roots rotted by a heavy watering just after cutting off the strings, and when the thick, fleshy roots rot they raise a bad smell, very similar to decayed Solanum tuberosum, alias potato.
When cutting the strings don't let a crude hand ruthlessly chop off all the growth. There may be several strong young shoots a foot or eighteen inches high that will quickly make other strings.
By planting at the last of June you ought to get four crops before planting time again, and will if the temperature of the house is kept never less than 60 degrees at night throughout the winter, and if it is 65 degrees so much the better; contrary to what would be the case with most plants, the warmer you grow it the harder it is, providing it is matured when cut. Being naturally a twiner among trees, it likes the shade, and is best shaded in summer and early spring.
I am sure it is wisest to plant every year. You get more strings; they are a more useful size, and more easily managed. After the second crop is cut, about New Year's, the bed will be greatly benefited by a top dressing of an inch of loam and cow manure. Their strong asparagus-like crowns of roots soon work to the surface and need this mulching. The smilax is a heavy feeder, so a strong soil, plenty of water when growing, and a good heat suit it.