Propagating Tender and Half-hardy Perennials
Tender and half-hardy perennials such as salvias and penstemons can be propagated by cuttings. Cuttings are best taken from young plants. In the case of penstemons and salvias we wait until July or August, when the current year’s plants have established themselves in the borders. Cuttings are taken early in the morning when the plants are most turgid.
Cuttings are taken from non-flowering shoots as they will root more easily, and stems are cut just above a bud.
The cutting is trimmed to a length of about 10 cm and the basal leaves are removed using a sharp razor blade. The soft tip is pinched out.
The cutting is then dipped in hormone rooting powder or liquid. A hole is made in a compost-filled pot using a dibber.
Several cuttings are planted in each pot with the first pair of leaves just above the level of the compost.
The cuttings are watered and placed on a propagation bench. Once established, they are potted on for overwintering in the greenhouse. Watering during the winter must be done very carefully to avoid rotting.