Asexual Propagation: Cuttings and Layering
For many plant species, a leaf, section of stem, or piece of root cut from a plant and lightly covered in soil, peat moss, or another growth medium develops a new, independent plant by generating the missing parts. Stimulated by hormones called auxins, a partially buried leaf or piece of stem, for example, develops roots on the buried portion, and a piece of root forms stems and leaves above the soil. Cuttings and layering are widely used for perennial plants, plants that grow back from the same roots year after year. Commercially, cuttings are the most important source for perennials, such as new fruit trees; conifers, including pine and spruce; a variety of shrubs, roses and honeysuckle, for example; and many florist blooms.
In layering, a new plant develops from a stem that is still attached to the parent plant. In nature, the stem simply arches over and spreads out on the ground. The parts of the stem that are in secure contact with the soil develop the roots, stems, and leaves of a new plant. The flexible stems of trailing blackberries, black raspberries, and several other species spread rapidly in this way.
Growers typically layer species that propagate naturally in this way. Layering is also used for plants such as filberts and Muscadine grapes that cannot be propagated easily by other methods. If plants do not layer naturally, a grower can induce them to layer by pinning the stems to the ground. Growers also layer plants by cutting them to the ground during the winter and covering the new spring shoots with soil, a technique called mound layering. This causes new roots to form along the buried lower portion of the new shoots, and new stems and leaves then grow up through the mound of soil. In a few weeks the new plants are cut away from the parent and planted in a garden or nursery. This technique enables a grower to produce many plants from a single parent that has desired traits. Apple trees, currants, and gooseberries are commonly propagated in this way. In air layering, often used with house plants, stems are partially cut and peat moss or sphagnum moss is wrapped around the wound, which is then covered in plastic wrap. A single plant develops from the place where the stem was cut.
In layering, a new plant develops from a stem that is still attached to the parent plant. In nature, the stem simply arches over and spreads out on the ground. The parts of the stem that are in secure contact with the soil develop the roots, stems, and leaves of a new plant. The flexible stems of trailing blackberries, black raspberries, and several other species spread rapidly in this way.
Growers typically layer species that propagate naturally in this way. Layering is also used for plants such as filberts and Muscadine grapes that cannot be propagated easily by other methods. If plants do not layer naturally, a grower can induce them to layer by pinning the stems to the ground. Growers also layer plants by cutting them to the ground during the winter and covering the new spring shoots with soil, a technique called mound layering. This causes new roots to form along the buried lower portion of the new shoots, and new stems and leaves then grow up through the mound of soil. In a few weeks the new plants are cut away from the parent and planted in a garden or nursery. This technique enables a grower to produce many plants from a single parent that has desired traits. Apple trees, currants, and gooseberries are commonly propagated in this way. In air layering, often used with house plants, stems are partially cut and peat moss or sphagnum moss is wrapped around the wound, which is then covered in plastic wrap. A single plant develops from the place where the stem was cut.
