avlegger

Avlegger is a term used in botany and horticulture to describe a shoot or stem that grows laterally from a plant and is capable of developing roots to form a new, separate plant. In Norwegian horticulture, avlegger refers to vegetative propagation by layering, where the new plant remains attached to the parent while its roots form, before being separated.

Layering can occur naturally on some plants or be induced by gardeners. The advantage is that the new plant retains the parent's genetic traits and often establishes quickly due to an existing vascular connection between the two plants. Layering is commonly used for shrubs, fruiting plants and ornamentals, and it is also a traditional method for propagating plants with difficult or slow aerial rooting.

Different forms of layering include simple layering (bending a flexible stem to the ground and covering a portion with soil), trench layering (burying a longer section in a shallow trench), tip layering (burying the tip of a stem), and air layering (inducing rooting on a section while it remains above ground by wounding, wrapping or applying rooting medium).

Usage examples include strawberries, which propagate via runners that act as avlegger, as well as many ornamental shrubs and fruit trees where clonal propagation is desirable. The process typically requires a period of proper moisture and protection until roots develop, after which the new plant is separated from the parent and transplanted.

Advantages of avlegger propagation include genetic fidelity to the parent and cost-effectiveness. Disadvantages include slower results compared with other methods, potential for disease transmission through the rooting zone, and the need for suitable timing and care to ensure successful rooting.