Air layering is a method of propagating fruit-bearing and flowering plants like apple, maple, cherry, and orange trees by creating smaller clones of the parent. Choose one of the tree’s newer branches and remove a ring of bark. Wrap damp sphagnum moss and plastic wrap around the exposed wood to keep moisture in and aid in the formation of roots. When you see roots growing, remove the branch and plant it in a pot to allow it to grow!
Part 1 Exposing the Wood
1. In the spring, begin air layering. When the roots have the summer growing season to form, air layering works best. Wait until mid-spring, when the trees’ blooms are just beginning to form. Choose a cloudy day to air layer the tree so that the sun does not stress it.
You can also experiment with air layering in the late summer months, though the roots may not grow as well if temperatures fall below freezing during the winter.
2. Choose a branch thicker than a pencil from last season’s growth. Look for branches that are at least 1–2 feet (30–61 cm) long and point up. Choose branches that have grown in the last year because they produce more roots than older, established branches. If the branch is not at least the thickness of a pencil, it may not grow well later on.
Choose growths from the current season instead if you’re air layering in the late summer.
Multiple branches on the same tree can be airlayered.
Examples of Plants to Air Layer
3. 3 inches (7.6 cm) around a leaf node, remove the foliage and twigs. Find a point where the leaves connect to the branch about 1 foot (30 cm) from the growth’s end. Pull the leaves off the branch by hand, leaving about 3 inches (7.6 cm) of space on either side of the node. Cut any twigs or branches that are in that area with a gardening knife or pruning shears.
If you remove all of the foliage from the branch, it will not grow as well when it is removed from the tree.
4. Make two parallel cuts through the bark, one on each side of the branch. Push a gardening knife blade into the bark just below the leaf node until it makes contact with solid wood. Cut a ring into the bark by guiding the knife around the branch. Lower the blade 1–12 inch (2.5–3.8 cm) down the branch and cut another ring around the circumference of the branch.
Applying too much pressure to the knife blade may result in a complete cut through the branch.
If you’re working with a slow-growing tree like maple, juniper, pine, or azalea, or you want to make a stronger trunk for a bonsai tree, wrap an 8-gauge copper wire around the branch beneath the node and pull it tight until it cuts into the bark. This will help the branch thicken before it begins to form roots.
5. Remove the bark ring from the branch. To begin peeling the bark off, place the knife against the top cut and push the blade down toward the bottom cut. Pinch the bark with your hand and slowly tear it away from the branch. Remove the bark from the ring until you see green or white wood beneath.
To get a better grip on the bark, you may need to make a vertical cut from the top ring to the bottom ring.
Put on gardening gloves before peeling off the bark if tree sap causes skin irritation.
6. Using the knife blade, scrape the exposed wood. Hold the knife with the blade parallel to the top of the ring. To remove the protective plant layer on the wood, drag the blade down to the bottom of the ring. As you work your way around the branch, scrape the wood up and down.
Rubbing the wood removes a layer of cells known as cambial tissue, which causes the bark to regrow if left on.
If you intend to air layer multiple trees, disinfect your knife blade with rubbing alcohol after each cut. This prevents diseases or bacteria from spreading between plants.
Part 2 Growing the Roots
1. To the exposed wood, apply a rooting hormone. Purchase a liquid rooting hormone to make it easier to apply to exposed wood. Dip a paintbrush in rooting hormone and allow any excess to drip off the bristles. To help increase the chances of roots forming, apply the rooting hormone to the ring you cut around the branch.
Rooting hormone can be purchased at your local gardening store or online.
Air layering trees do not necessitate the use of rooting hormone, but it may hasten growth.
2. In clean water, moisten a handful of sphagnum moss. Sphagnum moss is a common rooting medium that holds a lot of moisture. Soak a large handful of the moss in a container of water for 1–2 minutes. Remove the moss from the container and squeeze out any excess water so that it is not dripping wet.
Sphagnum moss can be purchased at your local gardening centre.
Wring out as much of the moss as possible; otherwise, the excess moisture may prevent roots from forming and cause rot.
3. Sphagnum moss should be wrapped around the exposed wood. Divide the moss ball in half and hold one in each of your hands. Apply the moss to the top and bottom of the branch, extending it 1 inch (2.5 cm) past the ring’s edges. Squeeze the moss tightly to ensure that it makes firm contact with the wood and remains in place.
To prevent the moss from falling off the branch, slowly let go of it. If it begins to slip, keep holding it or ask a helper to hold it while you work.
4. Wrap the moss in plastic wrap or aluminium foil to protect it. Remove from the roll a sheet of plastic cling wrap or aluminium foil large enough to cover the moss. Tightly press the wrap or foil against the moss and the branch to ensure firm contact. Wrap the moss completely around to trap moisture and promote healthy root growth.
Plastic wrap allows you to see when roots form more easily than foil, but both will work equally well.
Use dark-colored or opaque plastic wrap to keep the moss from drying out if the part of the branch with the moss receives direct sunlight throughout the day.
Tip: Tie the ends of the plastic wrap or aluminium foil to the branch with twine or twist ties if they don’t stay tight against the moss.
5. Allow the branch to remain on the tree until the moss fills with roots. Once a week, look through the wrap or peel back the foil to check for roots growing throughout the moss. If you don’t see any, leave the wrap on the branch and care for the tree as usual. If you see roots around the outside of the moss, you can remove the tree’s air layer.
It usually takes 6–8 weeks for healthy roots to fill in the moss, but this can vary depending on the climate and tree species.
The sphagnum moss should remain moist as long as it is tightly wrapped, but rewet it if it feels dry when checking for roots.
Part 3 Transplanting the Propagation
1. Potting soil should fill half of a pot with drainage holes. Choose a pot that is at least twice the diameter and height of the roots growing on the air layer. Make sure the pot has drainage holes on the bottom to prevent the soil from becoming waterlogged. Pour loosely into the pot a potting mix designed for trees.
Purchase potting mix from your local gardening store.
For propagation, you can use either clay or plastic pots.
Avoid planting the propagation directly in the ground because it may stress the tree and prevent it from growing healthy.
2. Remove the branch just below the new roots. Hold the branch steady with your nondominant hand just above the moss. Squeeze the handles of a pair of pruning shears together and grip the branch right beneath the moss. Lift the cut branch away from the tree, taking care not to damage or sever the roots.
If pruning shears aren’t cutting through the branch, use a tree saw instead.
3. Remove the roots from the plastic wrap or foil. To begin, carefully poke a hole in the plastic wrap or foil with your gardening knife. Pull the wrap apart by hand, taking care not to damage any of the roots inside. Remove as much of the wrap or foil as possible while leaving the moss around the roots to avoid stressing them.
If you remove the moss from the roots, the tree may become stressed and stop growing properly.
4. Backfill the pot with soil and plant the roots. Hold the cut branch vertically in the centre of the pot with your nondominant hand. Scoop more potting mix around the moss with a trowel or shovel until it is completely covered. Fill the soil until there is 1–2 inch (2.5–5.1 cm) of space between the lip of the pot and the surface of the soil.
Make a small mound of soil around the tree to keep it from becoming waterlogged or developing root rot.
5. Water the soil 2 in (5.1 cm) below the surface until it is moist. Wet the soil with a watering can until it begins to puddle on the surface. Allow the soil to absorb the water and drain it through the holes in the pot’s bottom. Fill the pot with water until it puddles again, then allow it to soak deeper into the roots. If the soil feels moist 2 inches (5.1 cm) below the surface, stop watering.
Water the tree whenever the soil 1 inch (2.5 cm) below the surface feels dry.
6. Keep the tree in a shady, out-of-the-way location. Place the tree near a north or south-facing window so that it receives light but is not directly in the sun. Make sure there are no draughts near it, as they can cause the soil to dry out and damage the tree. Keep the plant in its pot until the root system has adjusted to the new growing medium.
If you want to keep the pot outside, make sure it doesn’t get direct sunlight, or it will expend most of its energy on growing new leaves or blooms rather than roots.
7. Plant the new tree in the ground the following spring. Allow the roots of the plant to fully develop in the pot, which usually takes 4–5 months. When you’re ready to transplant, dig a hole twice the width and 6 inches (15 cm) deeper than the pot. Pull the tree carefully out of the pot and place it in the hole before filling it back in. Water the tree as usual to keep it from becoming stressed.
If you want to help the tree grow straight, install a vertical post next to it and tie the trunk to it.
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