Propagating apple trees in mid-air

Bob Dluzen
Special to The Detroit News

This week, I decided to try air layering a very old apple tree. I’m not sure what variety it is, but the fruit is delicious.

Air layering is an age-old process of propagating plants that involves encouraging a tree branch to sprout roots in mid-air while it is still connected to the tree. It is a good method to use on trees that are otherwise difficult to propagate.

Grafting is the way most apple trees are propagated, but there is a bit of a learning curve before you get the hang of it.

Air layering is simpler and good results can be achieved by gardeners with very little experience -- it’s the perfect solution if you only want a small number of trees.

The basic principle involves purposely damaging a small portion of a branch then covering it with sphagnum moss and wrapping the spot to keep it damp until roots form.

Once the roots develop and grow enough to fill the wrapping, the branch is cut from its location on the tree and potted. At that point the new plant is very delicate and must be carefully tended until it becomes accustomed to growing on its own.

Through the years gardeners have come up with many different ways of air-layering. Each iteration is an improvement as new materials are developed.

The gadget that I’m using is called the Rooting Pot system. It makes the entire process simpler and while it doesn’t guarantee success, it makes it much more likely that you’ll have positive results.

The first step in air layering is removing a small section of bark. That interrupts the flow of tree sap, which then stimulates plant hormones responsible for root growth.

A knife or other sharp tool is used to make two shallow, circular cuts through the back.
After peeling off the bark, you’re left with a ring of bare wood.

The open wound on the branch must have a substrate for the developing roots to grow into. Sphagnum moss can be used to fill the container but I opted to purchase the specially made plugs. The plugs are made from a peat moss-like material bound together with a polymer giving a firm, spongy texture that holds together.

The Root Pot opens in the middle to fit around the branch. It also has two water reservoirs to help keep the wounded branch from drying out.

Since roots only develop in the dark they must be shielded from sunlight. With a homemade set up, aluminum foil is often wrapped around the root ball.

Removable labels keep sunlight away. A special adhesive allows the labels to be peeled back for inspection then re-stuck back into place.
The top fits snugly but can be easily removed if necessary.

The pots will need to be checked from time to time to make sure they are not drying out. Water is easily added to the reservoirs by slightly lifting the top. They also sell a syringe that makes topping off the reservoirs easier and faster.

While this device is more expensive than using a homemade system, with some care it can be reused  year after year.