Propagation by Half Ripe Cuttings
Popular garden shrubs that can be propagated by half-ripe cuttings include abelia, buddleia, caryopteris, ceanothus, coroneaster, deutzia, escallonia, fuchsia, heathers, hydrangea, potentilla, rosemary, santolina, senecio, viburnum and weigela. Selecting suitable shoots is very important. The half-ripe cuttings, which are taken either in July, August or September, are obtained from the current year’s shoots. These shoots, as the name suggests, are only half ripe, that is, the wood has not completely hardened. You should avoid any shoots which are still rather soft.
These would then therefore have to be waited for. Preparing the cuttings is also very important. I find it best to pull off the shoots with a heel of older wood attached. The cuttings, when prepared, are 6 to 8 inches long. If the tip of a shoot is very soft then I cut it off. Some gardeners like to cut the shoots just below a leaf joint, but the method used depends upon personal preference. Heather cuttings, incidentally, are best taken with a heel and should be about l to 2inches in length. The leaves on the lower half of all cuttings must be cut with a sharp knife, close to the stem.
Suitable rooting mediums are essential to the process. I prefer a mixture of equal parts of loam, peat and sand, but a mixture of equal parts peat and sand is also suitable, particularly for cuttings of lime-hating plants. While inserting the cuttings it is important to know that the cuttings can be inserted in a cold frame, about 2inches apart each way. This should be done with half of their length below the soil. Before I insert them, however, I like to dip the base first in water and then in a hormone rooting powder to assist in rapid root development. I use a piece of wood that is shaped rather like a pencil or dibber, for making the planting holes. I then work on the cuttings thoroughly with this, paying particular attention to the base.
The base of each cutting must be in close contact with the soil, otherwise roots do not form. l water the cuttings thoroughly to settle them in and then close the frame. They like a moist, closed atmosphere as this encourages them to root more quickly. The frame can be kept closed for three or four weeks, opening it only for a few minutes each morning to allow condensation to drain from the underside of the glass. I also syringe the cuttings for the first week or two to keep the leaves moist and to prevent flagging.
After about four weeks a little ventilation can be given, by which time many of the cuttings will be starting to form roots. Ventilation should then be gradually increased. The rooted cuttings remain in the frame during the winter and should be given plenty of air when the weather is fine. They must be protected with a frame light during periods of heavy rain, snow or severe frost.