Slips are employed for increasing the number of an established variety or species. In the woody kinds, the young shoots are slipped off from the sides of the branches, etc, with the thumb and finger, instead of cutting them off with a knife, but is more commonly practised to the lower ligneous plants, such as sage, southernwood, rosemary, rue, and lavender. The best season of the year for effecting the work is generally in spring and beginning of summer, though many sorts will grow if planted at almost any time of the year.

Select the young shoots, chiefly of but one year's growth, and in many sorts the shoots of the year will grow the most readily, even if planted the summer they are produced, especially the hard wooded kinds ; but in the more soft wooded plants, the slips will also often readily grow when a year or two old, being careful always to choose the most robust shoots, situated on the outward part of the plants, from three to six, or eight, or ten inches long, slipping them off close to the branches. Clear off the lower leaves, then plant them two parts in the ground, giving occasional shade and water, if in summer, till properly rooted ; and towards autumn transplant them where they are to remain.

Many shrubby plants growing into large branches from the root, such as roses, spicas, and raspberries, may be slipped quite to the bottom, into separate plants, each furnished with roots, and may be planted either in nursery rows, or at once where they are to remain.

Herbaceous plants may be slipped into many separate plants, and it is effected by slipping off the increased suckers, or offsets of the root; some sorts, by the offsets from the sides of the heads of the plants ; and some few sorts by slips of their stocks or branches.

Slipping should generally be performed in the spring, or early part of autumn, which may be effected either by slipping the outside offsets with roots, as the plants stand in the ground, or, to perform it more effectually, you may take the whole plants up, and slip them into several separate parts, each slip being furnished also with roots, planting them, if small, in nursery rows a year, to gain strength ; or such as are strong, may be planted at once in the borders, etc. - Abercrombie.