Air Layering

Layering is a process which may occur naturally in plants, when growing stems root into the ground. This ability can be exploited in a technique to obtain a small number of new plants.

Air layering induces adventitious roots to form on a stem above ground - particularly useful for plants with an upright habit. Many plants can be propagated by this means. Below is an example on Schefflera arboricola (Dwarf Umbrella plant - a popular evergreen houseplant).

Here, the technique is shown on the Tasmanian native laurel, Anopterus glandulosus.

An appropriate straight length of current season's growth is selected and a sleeve is made with a plastic bag with the base cut out pulled down over the stem. A 1 - 2.5cm wide wound ring is made with a budding knife around the stem - this exposes the cambium layer which will respond hopefully by producing roots.

Rooting hormone applied can assist in this process.

Moistened coir fibre is then packed into the plastic sleeve to act as a rooting medium.

It is squeezed like a sausage and then each end of the sleeve is secured with appropriate wire or adhesive tape. The plastic sleeve is then covered in alfoil for insulation.

Opaque plastic bags are best because they retain moisture and reflect light, so the rooting medium does not become too hot. It also allows visibility of root production.

Most plants can respond in 2-3 months, but some stems can be slow to root and will need till the following spring. The rooted layer is removed by cutting through the stem at and angle just above a node on the parent plant. The new layer can then be potted in an appropriate potting mix.

Ref : RHS propagating plants, pg. 64