Plant Propagation Techniques – Heel Cuttings
Plant Propagation Techniques
There are several plant propagation techniques and this article covers the plant propagation technique of using heel.
Semi-often root more reliably if they are removed with a sliver of the parent stem. Some species — including pyracantha and Californian lilac ( ) — will root very poorly, or not at all, if this heel-like sliver is missing. The inclusion of a heel encourages roots to form, as it prevents the sap from draining away into the — the sap flows down from the leaves to help form the roots.
First, cut off a main shoot carrying several side-shoots, preferably without flowers. With a sharp knife, make a slanting cut into the main shoot beneath the junction with the side-shoot. Then cut in the opposite direction to remove the shoot. Heel cuttings should be 5-7.5cm (2-3in) long. If they are longer, trim from the tip. To balance any loss of difficult-to-root plants, it is wise to take a few extra cuttings.
Once the cuttings have been taken — with or without a heel — fill a pot to just below the rim with a proprietary cutting. A 7.5cm (3in) pot will take up to five cuttings, and a 12cm (5in) pot will take up to ten.
Make a hole in the compost, about one-third the length of the cutting. Insert the cutting and firm it with a dibber and your finger. Plant the other cuttings, then water them generously with a sprayer or a watering can with a fine rose.
The cuttings need a humid atmosphere to prevent them drying out. One simple method is to construct a cover from galvanized wire and a polythene bag as for tip cuttings. A box is best for a large number of cuttings, however, also covered with a polythene and wire frame. Alternatively, use a proprietary plastic propagating case, though the price may be quite high.
A cold frame is suitable for most semi-hardwood cuttings, but better rooting conditions are created of a source of heat is supplied from beneath, keeping the base of the cuttings slightly warmer than their tops. This can be done by placing the propagating container over the heating pipes in a heated greenhouse, or by using electric soil-warming cables in a cold frame. Propagating frames can be bought with built-in heating elements.
The compost above the heating source should be maintained at a steady temperature of 16-18°C (61-64°F) for most hardy plants. Cuttings generally root without bottom heat, however, but may take a little longer to do so.
After rooting, harden off the cuttings — acclimatize them to the drier or colder conditions they will meet outside by keeping them in a greenhouse or frame and raising the polythene, or piercing a few holes in it, to let in air. Keep them away from strong light.
One week later, raise the polythene still higher or make more holes in it. A further week later, remove the polythene altogether. By the following week the cuttings are ready for potting up singly.
Gently remove cuttings from the pot or box and tease them apart. Place potting compost in the bottom of a 9cm (3-1/2in) pot. Stand the young plant on this and then fill the pot with compost to just below the lowest pair of leaves. Firm the compost so that the surface is level and about 1.5cm (1/2in) below the rim, then water generously.
Keep the pot in a greenhouse or frame and never allow the compost to dry out. In three weeks, the roots should have reached the outside of the compost. Pot-on into a larger pot and place in an open cold frame. Keep those plants which are not fully hardy in a frost-free frame or greenhouse for the winter. Plant out in the spring when all danger of frost is past.
Other plant propagation techniques include: