Daniel Gill, Merrill, Thomas A. | 4/30/2005 1:29:52 AM
Get It Growing News For 05/27/05
By Dan Gill
LSU AgCenter Horticulturist
“Layering” is an easy way to propagate plants – to create new plants from those you already have.
There are many different ways to propagate plants. Planting seeds and rooting cuttings are two of the most common methods of propagation.
But another technique, called layering, is useful in propagating a wide variety of ornamental plants. And now is an excellent time to layer plants.
The major difference between layering and taking stem cuttings is that with layering roots are stimulated to form on the stem before it is severed from the parent plant – rather than after as we do with cuttings.
Layering has some real advantages over taking cuttings. Layering often is successful for plants that are difficult to root from cuttings. In addition, a much larger piece of the plant may be rooted when using layering, so you get a bigger plant quicker.
As with other forms of vegetative propagation (such as cuttings, division, grafting and tissue culture), using layering to propagate a plant creates offspring that are genetically identical to the parent plant. This means you can create as many exact copies (clones) as you want of a plant with desirable characteristics.
Despite all the hoopla over cloning animals, people have been cloning plants for thousands of years. Many or most of the ornamental plants in your landscape and home are clones, and most of the fruits and nuts you buy in the supermarket are produced by clones.
Layering can be done with herbaceous or woody plant materials. It is most often used on woody plants, since they tend to be more difficult to root from cuttings. But it can also be very useful for herbaceous plants, especially when you want to root a larger piece. I have layered coleus, ruellia, ornamental sweet potatoes and impatiens – to name a few.
Simple layering, as the name implies, is the easiest method to use. Its main requirement is that the plant have a branch that is low enough and supple enough to bend to the ground. If such a branch is not available, a variation called air layering can be used, but more on that later.
Here are the basic steps for simple layering. You will need a sharp knife, rooting hormone, a brick or stone and a trowel.
–Select a low, supple branch that can be bent to the ground without breaking. A part of the branch at least 8-12 inches back from the tip should be able to touch the ground.
–Bend the branch down and determine what part of the branch will come in contact with the soil and where it will touch the ground.
–Use the trowel to dig a shallow hole (about 3 inches deep) in the soil where the branch touched the ground.
–Use the knife to wound the branch at the point where it touched the ground. The branch must be wounded to induce roots to form, but do not completely cut through it. Several techniques may be used. A ring of bark about three-quarters of an inch wide can be scraped off, or a notch may be cut about halfway into the branch. You could also make a slanting cut into the branch (toward the branch tip) about halfway through it. A slanting cut should be wedged open with a small pebble or twig. Dust the wound with rooting hormone powder.
–Gently bend down the branch so that the wounded area is in the shallow hole, and cover it with soil. Place the stone or brick on top to hold the branch in place, since it will tend to spring back. At least 8-12 inches of the end of the branch should be sticking out of the soil.
This is an excellent time to simple layer, although it can be done virtually anytime. Roots should form readily during the warm summer months, and the layer on woody plants will be ready to cut off this fall.
Herbaceous plants root in as little as four to six weeks, but you should give woody plants, which root more slowly, four to six months. It won’t hurt the layer to carefully dig around it occasionally to check on root formation. When well-developed roots are observed (at least 1-3 inches long, depending on the size of the layer), cut the branch at the point just behind the roots. The new plant may be potted or planted into the landscape.
Air layering is done on plants when there are no branches that can be bent to the ground, but the principles are the same. Wound a branch using one of the above techniques, dust it with rooting hormone and wrap the wounded area with damp sphagnum moss. While holding the moss in place, wrap it with plastic and secure it in place by tying or taping it above and below the ball of moss. Do not allow the moss to dry out during rooting. Check periodically for roots, and cut off the layer just below the roots when they form.
Layering is one of the easiest and most reliable methods of propagating plants. It makes a wonderful gardening project, and you can use the resulting new plants yourself or give them to gardening friends.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.