This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
The Verbena has become so general a favorite, that a description of some of the best new varieties sent out the present Spring, and their culture, will no doubt prove acceptable to many of your readers. Rapid improvement has been made upon the Verbena within the last two seasons. The old type is entirely changed. We now possess every shade of color, and what has been so anxiously looked for by the florist, viz., large distinct eyes like the Auricula. The great difference in the habits of the Verbena adapts it as well for exhibition purposes as for the open ground.
To those who have the convenience and old plants, we would say that February is the best season for propagating by cuttings. Artificial heat is absolutely necessary for the purpose. The old plants should be forced into a vigorous growth and be syringed over once a day; this causes the young growths to develop roots on the stem below the leaves. The next thing to do is to prepare a well tempered hot-bed (if a regular propagating house is not at hand). Plenty of leaves or long straw should be mixed with the dung to make a lasting heat. When the fermenting materials are thoroughly mixed, shape the pile and put on it a one light frame made to fit the sash closely. Inside the frame place six inches of old tan or saw dust on top of the manure; make the surface smooth. When the heat is about 60°, get some pans or shallow boxes, fill them two inches deep with light soil, cover it with one inch of clean white sand, then make the cuttings of the young shoots on the old plants. Unlike most other cuttings, they need not be cut off close to a joint, but a portion of the stem may be left below the leaves. If the variety is scarce, one pair of leaves to a cutting is all that is necessary.
Insert the cuttings in the sand, one inch apart, press the sand close to the base of the cuttings and give them a gentle watering. Then plunge the pans or boxes into the tan or sawdust; shut up the frame and shade from bright sunshine. Water with a fine rosed watering-pot whenever the cuttings appear dry. Examine them every day, and remove all decaying leaves, which, if left, would soon destroy all the cuttings. With proper care, seven-eighths of the cuttings will be struck, i. e., rooted in twelve or fifteen days. They should then be inured gradually to the light and warm air. When " hardened off," pot them off, using three-inch pots, water and replace in a warm, close frame. As soon as the plants are established, they may be allowed an abundance of light and air. The leading branches must be pinched back occasionally to make the plants bushy. They may be planted out in the open ground towards the end of May.