Before winter has gone and the warm days of early spring cause our early-flowering shrubs to mature some very interesting flowers may be developed indoors on twigs of such plants. These flowers, the harbingers of spring, may be developed almost as well indoors as out of doors at a later date on the plants. The reason for such normal development under abnormal conditions is that the flowers, complete in miniature form, lie within the existing flower buds ready to burst forth when given sufficient heat and moisture.
When forcing cut stems of hard wooded ornamental plants in water in winter or early spring, the best results are secured by following a few simple rules. When flowers are desired, select branches of plants which produce flowers from buds formed the previous year. Otherwise, only leaves will result, which of course are sometimes desirable as an addition to the flowers of other sorts. Since all the flowers and leaves which will appear must come from buds already upon the twigs and branches be careful to cut only branches containing plump, full buds, especially when flowers are desired. It is possible to cut these branches at any time from February to April. After cutting the branches care must be taken to keep them from drying out and it is often well worth while to soak the whole twigs for a few hours in warm water, both before starting to force them and occasionally afterward at intervals of a week. This will loosen the bud scales, soften the whole fibre of the twig, and remove dust, thus taking the place of spring showers. The twigs should be from twelve to thirty inches long and placed- in fairly large receptacles with plenty of water. The water should be changed every second or third day and should have small pieces of charcoal added in order to help keep it sweet. Each two or three days it is advisable to make fresh cuts at the bottom ends of the twigs and it is often worth while to wash the cut ends in mild soap and water to prevent sliminess.
The forsythias or golden bells are the easiest and most successful plants for forcing in water. All sorts of currants are likely to be successful, even including the common black currant of our gardens. The dogwoods, especially the cornelian cherry, should not be overlooked. The fruit trees, such as apples, plums, cherries, and pears, may all be forced though they respond slowly and require several weeks' time and much patience. The lilacs do not seem to respond easily to forcing in water, nor do the magnolias. There are many common sorts of shrubs, some of which are listed below, which will provide flowers or catkins.
In general, those woody plants which flower first in the spring are the ones easiest to force in water. Those which require a longer period to develop flowers from the buds are not forced successfully.