To understand grafting, it is
important to know the terms scion and understock or stock. The scion is
the part of the stem with a growth bud of the variety one wishes to
propagate. An understock is that portion of the plant that furnishes the
root system. As a general rule, large stocks are more difficult to use for
grafting. A stock that is about 1/2 to 1 inch in diameter is a desirable
size. The scion should be taken of mature, current season's growth from
healthy plants one to three inches long with one or more growth or
vegetative buds. It will generally have three or more leaves.
The best season to graft is late
winter to early spring just before new growth begins. Camellia sasanqua or Camellia
oleifera is often used as understock because it is resistant to the
root rot disease. Cleft grafting is the most popular method of grafting
and will be described below.
- The understock should be
prepared by cutting off the top with sharp shears or a saw about
five inches above the soil. Loppers which squeeze the plant when
they cut should not be used as they can damage the cambium layer of
the understock. Make a sloping cut and trim smooth with a sharp
knife. A vertical incision should be made with a sharp knife about
two inches down the top side. To make incision, the knife may be
gently tapped with a hammer.
- Prepare the scion by making a
wedge-shaped cut at the base. Scions can be soaked up to 30 minutes
in a fungicide solution to discourage dieback. (Fig 1)
- Hold the slit open in the
understock with a screwdriver or knife. Insert the prepared scion so
that the cambium layers (green layer immediately inside the bark) on
the scion and understock will match. It is vital that the cambium
layers are in contact in order to have a successful graft. (Fig 2)
- The graft may be held tight
with a rubber band, waterproof string, or electrician's tape until
callusing of the union has occurred. The union point may be
protected with grafting wax, pruning compound, or aluminum foil.
(Fig 3)
- A covering such as a glass
jar, milk jug, soft drink bottle, or large styrofoam cup should be
used to cover the graft and keep the humidity high. It is also
desirable to cover the soil with an inch layer of sand. This will
ensure a tight fit of the top covering. If the covering is
transparent, the young graft should be protected from the sun with a
paper bag, etc. over the jar. (Fig 4)
- Callusing should start within
a few weeks and in two months be firmly knit. When firmly callused,
the jar can be raised gradually. If wilting appears at any time, the
jar should be put back on until it ceases. This is the most critical
phase of aftercare. It is often necessary to provide shade for this
young graft as the new growth may be quite tender. Burlap on a wire
frame or a bushel hamper with the northern exposure cut out may be
used.
- Grafts usually grow 15 - 30
inches the first season. Fertilize lightly with a liquid solution or
not at all the first year.
-
Fig. 1 - Scion showing
wedged-shaped cut at base.
Fig 2 - Scion inserted into understock with matching cambium
layers.
-
Fig 3 - Graft is held
tight with rubber band.
Fig 4 - Graft is covered with jar and shade.
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