When someone mentions something about layers, for some reason my mind goes immediately to the scene in the movie “Shrek” where he is explaining to Donkey that ogres are like onions because they both have layers. Of course, Donkey points out that not everyone likes onions, but everyone likes cake, which has layers -- and parfait, everyone loves parfait.
I have said the phrase, “onions have layers; ogres have layers” in my best Shrek voice on more that a few occasions, which is usually met with a look where I know the person is trying to figure out if my mom dropped me on my head as a child. I don’t care, it’s funny to me.
When you think of the term layering, the first thing that comes to mind may be clothing or a multi-tiered food item. However, in gardening, layering is a method of propagation.
The layer is the portion of the plant that has formed roots which can then be removed from the parent plant and become a freestanding clone of that plant. Everybody loves layers.
Propagation is the production of new plants by seeds, cutting, or other methods. Layering works by causing roots to form along a stem of the plant while still connected to the parent plant at which point it is removed and planted. The new plant, called a propagule, is able to use the resources of the parent plant while it is forming roots. Being that the propagule stays connected to the parent plant, it receives nourishment and water which reduces stress on the developing plant.
In comparison to starting from seed or cuttings, layering produces a larger plant in a short amount of time. Although layering can be done at any time of year, while the plant is actively growing in spring and summer are the best times.
There are a few layering techniques including air, tip, simple, mound and trench layering. The most popular methods are air, tip and simple layering, which will be covered here.
Air layering is ideal for propagating woody plants that otherwise would be difficult to start from a cutting. The materials you will need for this method are damp sphagnum moss, plastic wrap, aluminum foil, twist ties or twine, a sharp knife and rooting hormone.
This method starts by choosing a healthy branch to propagate. It should be at least the thickness of a pencil. Remove several inches of leaves from the branch where you intend to make your cuts. This section should be at least 12-inches and up to 2 feet from the branch tip. Do not remove the leaves above the top cut to the branch tip. Make two slices in the cleared area completely around the stem and all the way through the bark, about an inch or two apart. This is called girdling.
Remove the ring of bark between the two slices, and scrape off any green tissue. This plant tissue, called cambium tissue, will cause the bark to grow back. Apply rooting hormone to the cut area to help stimulate root growth.
Wrap a handful of the damp sphagnum around the girdled area and press firmly to ensure good contact. Make sure to squeeze excess water from the sphagnum so that the stem does not rot instead of producing roots. It should be damp, not wet. Secure the sphagnum in place with plastic wrap and secure the plastic with twist ties or twine.
At this point, it can be covered with foil to help protect the layer from excessive heat or light which would cause the sphagnum to dry out. The moss should stay moist if it is wrapped tightly, but check periodically to make sure it is still damp. Now hurry up and wait. The process may take a few months or up to a year to produce sufficient roots.
Start checking for roots around weeks six though eight and if there are none, rewrap tightly and wait a few weeks before checking again. When roots appear through the moss, the layer is ready to be removed from the parent plant. Cut below the newly formed roots and transplant to a pot to encourage further root system growth before planting it in the ground.
Tip and simple layering use relatively the same technique and work best on stems that are able to be bent down to the ground or to a container of soil. A sharp knife and rooting hormone are needed for this process.
For simple layering, bend a low-growing stem to the ground to find where the stem will be buried, making sure to leave 6 to 12 inches from the growing tip to the point of the bend. Remove the leaves from the section to be buried. Wound the bottom side of the branch by scraping gently with a knife and apply rooting hormone. Secure the stem to the ground, wounded side down, with a landscaping pin. Cover the area with soil. Check periodically to make sure the soil is moist and to see if there is root growth, at which point it can be removed and planted.
Tip layering follows the same premise, except that you bury the tip of the stem in a small 3- to 4-inch-deep hole and secure down with a landscaping pin. The tip will eventually start to grow up toward the soil surface, and roots should form at the bend in the stem.
The next time someone is talking about layers, try saying, “Ogres have layers; gardeners have layers.” They won’t get it, but I bet you laugh. Until next week, happy gardening.
— Irland, a member of the Limestone County Master Gardeners, can be reached at email@example.com. Visit https://mg.aces.edu/limestone for more information on the Limestone County Master Gardeners.