This section is from the book "The Gardener's Monthly And Horticulturist V23", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The system of culture adopted by the market growers around Paris in the production of white lilac, is not at all difficult to understand or carry out. There are a few points of importance, and when these are understood, the work will be found comparatively easy, so at least the most successful cultivators assure us. It is a matter of course, needful to begin with nicely rooted plants that are well furnished with flower buds, and it is equally important that the right sort should be selected. A high temperature must of necessity be provided, and the plants require to be kept in a dark or shaded place during the development of the flowers. Lilacs that naturally produce white flowers are not forced at all, and instead those bearing lilac flowers, the change in the color being effected by the treatment to which the plants are subjected. The best, and the one generally preferred by the Parisian growers, is Charles X. The plants are grown from the first in pots, or at least, after the second year of the suckers being detached from the parent stool, as a shorter growth and a greater abundance of flower-buds are obtained, and those who have had experience in the forcing of hardy shrubs of any kind will not need to be told that examples well established in pots can be forced with much greater success than those lifted from the borders.
After they are potted up due care must be taken to protect them from very severe frosts, by wintering them in cold houses or pits, and from heat and drought during the summer season by plunging the pots in a bed of some loose material. They require to be supplied very liberally with water to promote a strong growth, but in the season in which it is intended to force them watering should be suspended early in August, as by that time the flower buds will be well set. They must then be placed in a shady place, and as soon as the soil has become quite dry and the wood shows signs of shrivelling they are ready for forcing When removed to the stove or forcing pit place in a position from which the light can, wholly or in part be excluded. Maintain a temperature ranging between 70 deg. and 80 deg., and supply liberally with water of the same temperature as the house with which they are occupied. By starting a portion of the stock in August a supply of flowers may be had in October, and by starting other batches at intervals a succession of bloom may be maintained throughout the winter. - Gardener's Weekly Magazine.