Question: What is air layering?
Answer: Air layering is a propagation technique. A piece of the original plant is wounded and remains attached to the parent plant as the new plant develops. It can be done any time of year, but works best if done while plants are actively growing.
A cut is made on a plant shoot, which removes the phloem (the innermost layer of the bark). This wound stops the flow of nutrients, created during photosynthesis, from the leaves down to the roots. The photosynthates accumulate at the wound and if in the presence of a moist medium, stimulate adventitious buds to start growing roots.
Air layering takes longer than propagating from cuttings, but is relatively easy for the home gardener. The air layer section continues to receive critical water from the mother plant, unlike cuttings that are severed from the parent plant and can easily dry out and fail. Air layering produces a good-sized plant within one year depending on the species. This method can be used on woody plants like camellias, magnolias, Japanese maples, azaleas and roses. It can also be used on houseplants that have lost their lower leaves and have taken on a leggy (bare stem) appearance.
To successfully air layer a plant, you will need to gather: a clean sharp knife, sphagnum moss, polyethylene film, aluminum foil, and twist ties, twine or electricians tape. Rooting hormones may improve rooting success but are not necessary.
Soak sphagnum moss in water for several hours before propagating to ensure complete saturation. Wring out the sphagnum moss before applying to plants. The moss should be moist like a damp sponge. Excess water can cause deterioration and decay of plant tissues.
For optimum results, select branches that are the size of a pencil or larger. If air layering in the spring, select shoots produced during the previous season. If using this technique in mid-summer, select shoots produced during the current season. Choose an area just below a node and remove the leaves a few inches above and below this point.
Make two parallel incisions in the bark about 1.5 inches apart.
Next, cut a line in the bark between the incisions.
Remove the bark and scrape the cambium (green tissue) away to prevent callus tissue from forming.
Apply rooting hormone to the exposed wound. Wrap the wound with a hand full of damp sphagnum moss.
Next, wrap polyethylene film around the moss and secure each end of the film with twist ties, twine or electrical tape. The plastic film should contain all of the moss and should be snug against the bark above and below the wound. It is important to retain moisture around the wound but limit excessive amounts, which could lead to disease.
If the plant receives a lot of direct sunlight, or if the weather is hot, wrap aluminum foil around the mass to help retain moisture. Check the moss weekly to ensure that it remains moist. If the moss dries out the layering will fail.
After roots are visible throughout the moss, the new plant can be removed from the parent plant. This can take several weeks to months depending on the plant. Remove the newly rooted plant just below the ball of moss and roots. Carefully remove the plastic film and place the new plant in a container with potting soil. Be careful not to disturb the roots or sphagnum moss. Keep the new plant well-watered and out of direct sunlight until the new root system is well developed.