by Glenn Davis, UCCE Master
Gardener, El Dorado County
February 2003
While going through my annual “blackberry kill” I marveled at
the ability of that plant to spread itself all over the place. Everywhere it
touched the ground it produced another new blackberry bush. Botanists refer to
this as adventitious rooting, gardeners refer to it as “layering.”
Many plants reproduce exact replicas by growing a new plant
from the original material of the parent plant; seed reproduction, on the other
hand, unless carefully controlled, has a greater chance of producing offspring that
differ from the parent.
So if you want an exact replica of one of your plants you can
reproduce it by dividing, using cuttings, grafting or layering. Not all plants
can be divided, not all can be reproduced by cutting, not all respond well to
grafting and not all can be layered. Sometimes, as in the case of the
blackberry, plants will naturally layer themselves; sometimes the root system
enlarges and produces another underground root that eventually produces another
plant.
If you are a home gardener and want to increase the number of
a certain plant, for your own enjoyment or to share with a friend, layering might
be the easiest method if the conditions are right. Conifers and broad-leafed
evergreens do not respond well to layering attempts. On the other hand berries,
roses, daphnes, azaleas, camellias, clematis, ivy, honeysuckle, and oleander,
to name a few, can be layered.
Layering involves placing a part of the plant in a rooting
mode by either putting it underground or creating a rooting atmosphere around
it. It can be the burial of a low branch, the burial of the entire plant, the
burial of the tip of a plant or creating a rooting spot on a vertical branch.
Simple layering involves making a small wound on the bottom
side of a branch near the ground; application of a rooting hormone to the wound
is next and the branch is then placed underground with a weight to hold it
there. The branch needs to be only an inch or so underground. It helps if the
tip of the branch has been cut off in the early spring and if the leaves in the
layered area are removed. The branch coming out of the layering area should be
staked to keep it vertical. Ground preparation in the layered area should
include some composted material that would make it easier for the roots to
become established. Once the roots have become established the branch is cut
from the parent plant and placed in a more permanent location. If there is a
stub on the parent plant cut this back so there is no dead wood remaining.
Tip layering follows the same process with the exception of
cutting off the tip of the branch in the early spring. Layering is most often
done in the early spring, tip layering on the other hand can be done on berries
in the middle of summer. Once the tip has been placed in the ground make sure
it is secure and will not snap back up again.
If you are trying to reproduce a great many plants you can use
two methods, compound layering and stool layering. Both are similar to simple layering; stool layering is a burial
of the entire plant and compound layering is simple layering many times on the
same branch. Stool layering should be started in late winter when you cut back
the plant to a couple of inches above the ground. Shoots usually sprout from
this stub and when they have reached about 6 inches or so, mound soil around
them and continue to do so until about a foot high mound is reached. Then cover
the entire mound with mulch and check occasionally for roots on the shoots. Once
the shoots have rooted wash off the mulch and cut off the rooted sections and
move them to a permanent location.
Air layering is done on vertical branches; a chip of bark is
removed from the branch and it is treated with a rooting hormone. The wound is
then covered with damp sphagnum moss and black plastic is wrapped over the moss
and sealed at each end. Do this in the early spring on new growth and check for
roots by gently feeling the plastic. Once the roots have formed cut the branch
from the plant and place it in a permanent location.
Not all plants can be layered, however experimenting in the
garden is part of the fun and increasing your garden inventory can be part of
the reward.
For more information on this subject or any garden question,
contact the El Dorado County Master Gardeners, 621-5512, Monday through Friday,
9 am to noon.