Layering for New Plants
Some Saturday morning this spring or early summer, take a few minutes to produce some new shrubs from your favorite ones by layering. You can layer to propagate berry bushes such as currants and gooseberries, bramble fruits like raspberries and blackberries, and even grapevines. If you'd like to expand your groundcover, then start new plants of pachysandra or periwinkle by layering.
Ornamental shrubs such as barberry, escallonia, daphne, flowering quince, forsythia, lilacs, magnolias, mock orange, shrub roses, viburnum, wisteria, azaleas, and rhododendrons are all candidates for layering.
Many of these plants layer naturally, when a low branch happens to touch the ground and roots sprout. I've given away several rosemary bushes that naturally layered. My new escallonia plants, created by unintentional layering, are ready to transplant to a new location.
So, why not propagate intentionally and expand your collection of favorite cultivars?
Another form of natural layering is plants that send out stolons, such as strawberries, ajuga, and spider plant; or plants that have offsets, such as bananas, many bromeliads, and hens and chicks.
Methods of Layering
Unlike cuttings, a layered branch is nourished by the parent plant while the roots are forming, so timing isn't as critical. The best time, however, is during early spring or summer, when the plant is actively growing.
There are several methods of layering: simple layering, trench layering, compound layering, tip layering, mounding, and air layering.
Look for a healthy branch on your shrub that is growing close to the ground. These are the easiest branches to layer. Cut or stress the cambium layer where you want the rooting to occur, but be careful not to sever it completely. Scrape back the soil to form a depression beneath the branch, and remove any leaves that would be under soil. Peg the stressed stem into the dip and cover with soft soil.
If you want, you can apply rooting hormone to encourage rooting, but this is not really necessary. You may need to place a rock on top, to prevent any movement. This method works well with rhododendrons and azaleas, currants, forsythia, cornus, box, rosemary, and climbing roses.
This is a good method of layering, successful with plants like forsythias and bramble bushes. Just peg the tip of a branch under soil, and wait for new growth to appear and good roots to form.
This is how blackberry or brambles can soon over-run an area in the wild!
Trench and Compound Layering
Trench layering is similar to simple layering, but with this you are using a much longer section of plant, and you'll have multiple new plants rather than one.
With compound layering, you are layering a long stem, with some plant (with a bud or leaf section) exposed and some covered to root. Honeysuckle, grapevines, and wisteria are all good candidates for this method, as the long flexible vines are easy to bury in a trench, each section with a bud showing above ground.
Notice how some groundcovers send out runners, which root at leaf junctions. This is another example of natural layering.
By covering the base of a plant with extra soil or compost and allowing the plant some time to form roots on the buried branches, you can create newly rooted plants.
Small shrubs like heather, thyme, and oregano work great with this technique.
This is a more complex way of layering, and it differs in that you are not burying a branch in the soil, but using an aerial branch to root. Again, the branch is wounded or abraded, and rooting hormone applied to encourage rooting.
Then the area is packed with damp peat moss and wrapped with a piece of black plastic. Both ends of the plastic must be tied to seal them. Once roots have formed, simply cut below the plastic, and plant your new shrub.
This works well for rhododendrons, magnolias, and ficus.
An old cottager's custom was to insert a grain of wheat into the slit or cut in the branch. This has two purposes — it keeps the cut open and, as it sprouts in the damp earth, it releases growth hormones that stimulate rooting. So, if you're having trouble getting rooting to start, give it a try.
With layering and a bit of patience, you'll get a lot more bang for your landscaping buck. A single bush could have the makings of a whole hedge in just one year!