This section is from the book "The Gardener's Monthly And Horticulturist V21", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
There may not be anything new in the following method of propagation; still as I never saw or heard of it before hitting on it, I thought there might be some of your readers like myself.
It is nearly always desirable to increase new plants, and plants of slow growth faster than they furnish wood for the purpose. It can be increased from two to ten fold by commencing at the point of a well established plant, and splitting it downward an inch or more according to its nature and growth, leaving it in that condition for a day or two. Then commence at the point of these two halves, and split them down also into quarters. Leave them from two to ten days to callous, when each quarter will make a cutting almost certain to grow, even if cut into single eyes. As soon as the cuttings have rooted, been potted and well established, split them also half their length, and in a few days more continue the split down to, and through the roots, making two or more plants instead of one. I find it advantageous with tricolored geraniums, double primulas, etc. It does not endanger the life of the parent plant, for they can be taken off a few at a time, thereby lessening the shock that would occur to some plants if the whole top were taken at one sweep. The parent plant goes right on growing without the necessity for repotting. The young growth of most hard wooded plants might be facilitated in the same way.
There is no rotting in the cutting bench as is often the case with whole cuttings of tricolor geraniums, poinsettas, etc.