Cuttings are another form of vegetative propagation. This method works well on many species and cultivars. Cuttings are the primary method of propagation for many of the hybrids that have become popular. Tip cuttings are taken from non-flowering stems, or portions of flowering stems near the base and can be used when they are firm but not woody. They may be taken from late spring through fall, depending on what facilities are available for rooting the cuttings and growing them until time to plant out. They should be just a few inches long, with four to six pairs of nodes, depending on the size of the plant and leaves and the spacing of the nodes.
Gently remove leaves from the bottom of the stem so that one or two pairs of nodes are exposed. For the top cut, cut just above the nodes still bearing leaves. The cutting may be dusted with a rooting hormone powder or dipped in a root stimulating liquid, but should be tapped firmly to remove excess before insertion. The rooting medium can be a mix of perlite, vermiculite and/or sand, three to five inches deep. A soil heating cable below the rooting medium is used by many growers but is not absolutely necessary. Again, all materials used should be clean to avoid disease. The rooting medium should be well-dampened before the insertion. Open a hole or slice before the insertion so that rooting powder will not be rubbed off when inserting the cutting. Leaves should be above the rooting medium when the cutting is in place. Once the cuttings are firmed in, they will need warmth, light, but not direct sun, some air movement and humidity. The cuttings must not be allowed to wilt, but they must have some air movement about them to prevent disease. A greenhouse is an ideal location for growing cuttings, but it can be done in cold frames and in pots enclosed in clear plastic bags.
The bags should not touch the leaves. These plastic covered containers should be kept out of direct sun to prevent over heating. Each species being propagated should be separated from others because they do not root at the same rate. When roots are well developed, the new plants are transferred to a soil mix and watered with a dilute liquid fertilizer. Once plants are well rooted in the growing mix and conditions are right outdoors, plants can be set out.