If your soil is poor, enrich it where the stem will be buried by forking in compost or well-rotted manure to a depth of 25 centimetres.
Using a spade, dig a narrow trench about 20 centimetres deep at the point where the branch to be layered will lie, and long enough to accommodate the stem.Keeping the branch as flat as possible, bend it downward and lay it along the trench. (Young, green shoots won’t snap, but bending them sharply will restrict the flow of nutrients and hormones, which is vital for forming new roots.)
Leave at least 15 centimetres of the tip of the stem above ground. Keep the layer in place by pegging it down with metal hoops—sections of wire hangers bent into a U-shape work well. As you fill the rest of the trench with topsoil, use a small stake to keep the exposed tip growing absolutely upright; otherwise the main stem of the new plant will lean to one side, causing uneven growth. Tread soil down firmly. Water well.
Keep the layer well watered throughout the summer. Most plants will produce roots over the course of one growing season, but some may take up to three years (such as magnolia, witch hazel and broadleaf evergreens). To test if the layer is ready for transplanting, give the shoot a gentle tug; if you feel firm resistance, rooting has occurred. In the fall, to prepare the layer for transplanting, sever the branch from the parent plant using secateurs, but leave the layer in the same spot over winter so it develops a stronger root system. Transplant the following spring.
For faster rooting results, you can do one of two things:
- Use a sharp, sterile knife to girdle the layered stem (remove a ring of bark two centimetres wide all the way around the branch), four to five centimetres from the parent plant.
- Tie a piece of copper wire around the layered stem, four to five centimetres from the parent plant. Tighten the wire as much as you can using only your fingers (pliers will tighten it too much).