‘Layering’ is a method of obtaining new plants by asexual or vegetative propagation.
Propagating plants by the ‘layering’ technique is one of these easiest ways to produce a few extra specimens from your choice shrub or houseplant. There are several methods of layering plants, but the one thing they all have in common, is that nothing is taken off the parent plant, until the layer has succeeded in producing additional roots.
Layering is particularly useful in producing extra plants from shrubs which are difficult to root from cuttings. As with taking cuttings, you are assured of reproducing an identical plant to the parent – a clone if you wish! With plants grown from seed, there can be wide variations in the vigor, general appearance and flower colour.
Stool layering is practiced at commercial nurseries on a large scale – being the most efficient way of producing extra stock of certain plants. The other forms of layering are generally used when just an extra plant or so is required; or with particularly difficult shrubs that do not grow well from cuttings..
All methods of layering involve trying to get a stem to produce roots whilst still attached to the parent plant. The joints – or nodes as they are known – are important when taking ordinary cuttings, for most plants are ‘active’ at the nodal joint insofar as producing roots are concerned. That is why, when cuttings are taken, the cut is normally just below a leaf bud joint. Some – such as – clematis produce roots between the leaf joints rather than at the nodes.
Most active gardeners will have at sometime seen roots growing from a stem part that has either been damaged, or has been in contact with the ground. This is particularly the case where plants spread by stolons – stems which root individually as they creep away from the parent plant. Many perennial plants send out low growing shoots which invariably root into the ground.
Most layering techniques – other than air layering – involves bending a suitable stem down to the ground and then securing it either with a pin, peg, a mound of soil or even a brick!
The process can be started at any time of the year, but the spring is the best, with new, pliable shoots. Many shrubs have low growing or arching shoots or branches which can easily be pegged down to the ground.
Before pinning the stem to or into the ground, it is best to slightly damage the underside of the stem – away from the bud – by scraping a little bark off or making a shallow cut near the reverse of the dormant bud. There is no need for any other treatment, though rooting hormone can be used into the damaged are if desired.
Where thick stems are used for layering – such as older stems of Magnolias or Rhododendrons – a cut near the leaf joint can be held open by simply inserting a small piece of twig or even a small pebble.
Basic Layering Technique; Tip Layer; Mound or Stool Layering: