Chapter 20

Vegetative Plant Propagation

Plant Propagation by Layering

Layering is a technique by which adventitious roots are formed on a stem while still attached to the plant. It is mostly used on those species that fail to root from stem or root cuttings. Because an entire branch of the parent plant is often needed to form a single new plant, this method is useful for propagating only a few plants from each parent. This method of vegetative propagation method is highly successful because it helps the cutting avoid shortages of water and carbon dioxide that often affect cuttings from other methods of propagation. Layering is enhanced by girdling the stem where it is bent, by wounding one side of the stem, or by bending it very sharply.

Simple Layering

Simple layering may be performed whenever a plant has a branch low enough to be pulled down to the ground. Bury the branch several inches deep in the soil, making sure the shoot tip protrudes from the soil (See Figure 20.4). Bend the tip into a vertical position and stake in place to hold the tip in an upright position. The sharp bend often induces rooting, but cutting the lower side of the branch or twisting the stem to loosen the bark may help. Dust the cut with a rooting hormone. If the cut was made on the topside, give the branch a half twist. 

Compound (serpentine) Layering

Compound layering is suitable for plants with flexible stems (e.g., vines) and requires that the shoot be alternately covered and exposed (See Figure 20.5). This technique is simple layering performed multiple times.

Air Layering

Air layering, a popular method of propagating houseplants, involves establishing a root system on the plant’s stem above the ground. The air layer may be made at any point on a stem of proper maturity. On many plants, a good location is about 12 inches (30 cm) from the tip. The procedure for air layering is as follows. Remove all leaves several inches on either side of the point where the layer is to be made. From the center of the layering area, make a slanting cut upward an inch or more in length and about halfway through the branch (See Figure 20.6).

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