Everyone has heard of propagating new plants from cuttings – us gardeners are notorious for helping ourselves to cuttings from here there and everywhere – usually with the excuse that we are doing the owners a favour by pruning their overgrown plants…. However there is a less well know though much more effective way of creating a new plant from an old – and no I’m not going to try to explain how to make your own kitchen tissue propagation laboratory!
What I’m going to tell you about is Air-Layering a highly effective technique which has been used by farmers for thousands of years.
Propagation by Layering
Classic standard layering is when you take a runner from a “mother plant” make a small wound in the runner, apply some rooting powder and insert it into the soil. This method has a huge advantage over simply taking a cutting and trying to get it to root because when using the layering technique, the “cutting” is still attached to its mother making it much more likely to root and giving it a much faster and stronger start to life as a new independent plantling.
Propagation by Air Layering
Air layering addresses the problem of applying the layering technique of propagation to plants that do not have soft and supple stems which are easily bent into the ground such as rhododendrons, ficus, camellia and acers. What we do is to take the ground up into the air around the “cutting” and root it there.
Air Layering Technique
Choose a shoot from the plant you want to propagate and remove any leaves from a 6 inch length of the stem 9 inches from the top of the stem. Tie up the leaves on the 9 inches at the stem top so that they won’t interfere with the air layering below them. Now carefully remove a complete ring of bark both the out brown bark and the inner green cambium layer so that you can see the inner white of the stem (the ring should be about 1cm high) from the 6 inch leaf clear part of the stem – your stem is now ready to be rooted.
Cover the stripped ring of the stem with rooting powder . Now take a handful of damp sphagnum moss and wrap it around the stem – wrap the sphagnum moss in polythene secured at either end with a suitable tie (regular string is fine).
The recommended time to propagate by air layering is from April until June and it can take anything from two weeks up to a year for sufficient roots to form that you can cut the newly rooted plantlet from its mother and pot it up on its own. This is where believe it or not there is some contention over the colour of polythene used to wrap the rooting medium. If you are propagating a fast growing species such as ficus, you can use a clear polythene wrap – and you will easily be able to see the new roots when they quickly form. For a slow growing species such as pine, you should use black polythene which avoids light creating algae growing conditions which can smother new roots.
Ensure the sphagnum moss is kep moist but not soaking – do not allow it to dry out.
When potting up the new plantlet take care not to damage the new roots and in no circumstances try to remove the sphagnum moss.
Check for new roots at least once a month but not more often than once each fortnight.