Walter Reeves: Tips for successful air layering

Q: I am interested in refining my air layering skills. I have watched many online videos, and I have had very good success with citrus trees such as lemon, lime, and mandarin orange. However, I am having great difficulty air layering Japanese maple trees and non-fruit-bearing weeping mulberry trees. Why am I not having success with these when I use the same techniques as I do with the citrus trees? Barry Gilbert, email

A: Air layering is a great way to produce new plants that are identical to the parent by encouraging small limbs to form roots while attached to the main plant. The process involves wounding a limb and wrapping the wound with sphagnum moss that’s kept moist for eight to 12 weeks. After roots have formed in the moss, the rooted limb can be clipped off and planted. Once you are familiar with the simple steps, success with some plants comes easily. But plants differ from one another. Some need high temperatures for roots to form; some have to be at a particular stage of growth before roots will form. Your Japanese maple and mulberry must require different propagation techniques from your other plants. I’m not an air layering expert, but I do have some thoughts on why your attempts to root Japanese maple and mulberry might have failed.

1. Failure to control moisture in your rooting medium: If it gets too wet or too dry, even for a couple of days, the roots suffer. Check the top of the plastic wrap to be sure rainwater is not coming down the stem and going into the rooting space. I use black electricians tape to seal the edge of the plastic to the bark. The gardener should be the only person adding moisture to the moss inside the plastic wrap. A hypodermic needle can be used to add water if it seems too dry.