While most people are quite adept in varying methods of propagating house plants from seeds, stems or leaf cuttings, few are familiar with the idea of air layering.
The Concept of Air Layering
Essentially, air layering allows growers to root the branches of plants that are difficult to propagate through cuttings - in particular woody plants like Ficus benjamina (Weeping Fig), Ficus lyrata (Fiddle Leaf Fig) and Ficus binnendijkii (Long Leaf Fig); Dracaena fragrans (Corn Plant), Ficus elastica (India Rubber Tree) and Yucca elephantipes (Yucca, Elephant Yucca), as well as Schefflera arboricola (Umbrella Tree) and many others - while they are still attached to their parent plant.
This method is also useful if the goal is to have a new plant that is larger than a plant a stem or leaf cutting could provide in the same amount of time.
Required Materials and Tools
The following materials and tools are necessary to begin air layering plants to be propagated:
- Sphagnum moss (available from most garden centres/ nurseries)
- Bowl of water
- Sharp knife
- Piece of hard, thin plastic (a little longer than the diameter of the branch to be rooted; a piece cut out of a yoghurt pot, plastic bottle or plant tag will do)
- Transparent plastic foil/ bag, approximately 30 x 30 cm (12 x 12 in) in size
The first step is to soak enough of the sphagnum moss to create a fist-size ball when pressed lightly (after squeezing out excess water) in the bowl of water. While the moss is soaking, the plastic foil or bag can be cut to size, followed by cutting two pieces of the string long enough to wrap a few times around the branch and tie with ease - around 20 to 25 cm (8 to 10 in) should be sufficient - and cutting the piece/s of plastic to size.
After selecting the branch to be rooted, an upward slanting cut (approximately 45 degrees) needs to be made (using the sharp knife) just below a leaf-node (the spot where a leaf was/ is attached to the branch). As around 10 to 20 cm (4 to 8 in) of leaf-free branch is required, it may be necessary to remove some leaves.
The cut should go between half and two-thirds of the way through the branch. It is vital to ensure the cut is not too deep, as the branch may break if cut too far. Next, the small plastic piece is inserted into the cut. Doing this will prevent the cut from healing shut and encourage the branch to develop roots instead.
The soaked moss is now wrapped around the cut and the area around it, taking care not to wrap it too tightly. When finished, the moss should feel soft and sponge-like. Holding the moss-ball in place, the clear plastic now needs to be wrapped tightly around the moss (it may help to get some assistance at this point) and secured above and below the moss with the prepared string. It may also be a good idea to support the branch by tying it to a stake/ cane just above the moss-ball to stop it from snapping.
Depending on the species of plant, roots should begin to develop and grow into the moss over the next few weeks/ months. The clear plastic covering will make it easy to check on progress without having to disturb the process by unwrapping the moss-ball. If no roots show within the expected time period, it may become necessary to carefully open one end of the plastic and check whether the moss-ball is still moist enough.
Once the roots are well developed, the branch can be cut off below the wrapped moss-ball, and after removing the plastic foil - taking care not to disturb the roots/ moss too much - the new plant can be potted up in a suitable quality potting mix. The pot/ container should not be much bigger than the root ball, as the soil in a larger pot will hold too much water for the young plant's roots to cope with, causing them to rot.
For the same reason, watering should also be done with care, especially for the first three or four weeks. While the soil should be kept slightly moist to prevent wilting, it should never be allowed to be really wet or soggy.