Article from The
Master Gardening Bench, Manatee County Master Gardener Newsletter
by John Dawson
Air Layering
Many low sprawling plants can naturally
reproduce themselves by a process known as layering. Layering occurs
when a portion of a plant (limb, branch, or vine) makes contact with
the ground. Friction with the ground removes the protective portion of
the plant and starts the process of creating roots, which initially
anchors the contact and eventually provides nutrients for what becomes
a new plant. While this is happening, the new plant is still receiving
nutrition from the mother plant giving it a greater chance of survival
than if it was started as a cutting. Think of it as a plant’s
umbilical cord.
Gardeners can duplicate this process by
scraping a portion of the outer protective layer (bark), pinning down
the branch, stem or vine to the ground and covering with soil. The
leafy portion must be kept above ground. Depending on the plant, the
new plant can be separated from the parent plant after several months
and replanted.
Air layering or "marcotting" is a process used
for plants that have branches too far from the ground to reproduce this
way naturally. Instead of bringing the plant to the ground, we bring
the ground up to the plant!
Example: You have a small fruit tree
you wish to propagate. You’ve tried growing from seed, growing
from cuttings, and have had several attempts with grafting fail. Air
layering is your next best alternative. Air layering should be
attempted when new growth starts to appear (usually in the spring).
Choose
a vertical limb that’s one to two years old, about
¼” to ¾” in diameter. Measure from the tip of
the branch down 12 to 18”. At this point, clear the limb of any
leaves or small twigs, leaving a cleared area about 12” long. At
the midpoint of the cleared area, you should use a sharp knife to cut
two parallel cuts about ½” to 1” apart around the
limb just deep enough to remove the outer bark, revealing the cambium.
The cambium layer then must be scraped away, if not, then new bark will
form instead of roots.
A rooting hormone can be applied to the upper side of the exposed
woo to promote quicker rooting. The entire exposed area then needs to
be covered with moist (not sopping wet) sphagnum (not peat!) moss. The
moss is then surrounded by a sheet of clear plastic and held in place
by twist ties on each end. The ties need to be tight enough to keep
insects out and trap moisture in. To prevent overheating, the plastic
should be covered by metal foil.
After several months, check
area under the plastic for roots by removing the foil. Roots should be
clearly visible through the clear plastic. If no roots are visible,
recover and check again weeks later. Some trees may require a year to
develop sufficient roots. When ready, the new tree can be removed by
cutting away below the new roots. Remove the plastic wrap and carefully
remove excess moss while spreading out restricted roots. It is not
necessary to remove all entangled moss.
Gently plant it in a
right-sized container (big enough to avoid tipping over) filled with
moist soil while taking care to avoid breaking tender roots. The new
plant should then be moved to (mostly) shaded and protected spot (out
of any strong winds.) It is important to keep the new plant moist
(misting the leaves) for several weeks. You can also try placing a
large plastic bag over the plant (ensure the bag does not contact
leaves) to retain moisture. The new tree should be hardened off after
several weeks and then planted in its new location.
 |
Step
1 
Gather
materials – Sharp knife, clear plastic wrap, metal foil, sphagnum
moss, twist ties, rooting hormone, water, and basin. Soak sphagnum moss
for several minutes. |
 |
Step
2
Clear working area and make cuts to remove bark and cambium. Place
rooting hormone near top of cut. |
 |
Step
3
Wring
out sphagnum moss so that it is moist, not sopping wet. Place sphagnum
moss around entire work area and wrap with clear wrap and secure both
top and bottom with twist ties. |
 |
Step 4
Wrap foil around entire encasement to prevent overheating from sun.
Check for roots in a couple of months.
|
 |
Back to
Air Layering
Index
|
|
