Propagating a Bonsai Tree By Grafting And Air Layering

Many bonsai enthusiasts derive great pleasure from growing their own
bonsai trees. Some like to plant the seeds themselves and nurture them
from sprouts to young trees, ready for shaping. Others prefer to take
cuttings from a "parent tree" so they can grow a new tree with the
parent tree's characteristics. Still others like to grow bonsai from
air layering-a technique that's been practiced in Asia for thousands
of years-or grafting, which is typically used by gardeners at bonsai
nurseries. These last two propagation techniques are a bit more
difficult to master than growing from seeds or cuttings, but they are
reliable methods to grow your own bonsai.Layering involves creating a
new bonsai from the developed branches of fully-grown trees or shrubs.
One of its advantages is that you will have a mature tree in one
growing season, much faster than other methods. The principal behind
layering involves intentionally injuring the tree to interrupt the
flow of nutrients, or sap, from its roots to a branch. In order to
survive, the injured part of the branch will first form a callus and
then new buds that form roots to pull nutrients and moisture from the
environment. This branch will then eventually become a new bonsai.
Layering should always be done in the spring when the tree is growing
and the sap is rising, no matter what the species.There are two
techniques to air-layer a tree: the tourniquet method and the ring
method. With the tourniquet method, you wrap a wire tightly around the
branch to partially stop the flow of sap. As the branch slowly grows,
the wire will become tighter, digging into the bark and then
underlying soft, green cambium layer, stopping the flow of nutrients.
The branch will be forced to grow new roots just above the wire. Some
bonsai experts wrap the new rooting area with sphagnum moss, peat
moss, or a plastic bag to protect it. Make sure you can water the area
through the wrapping. Good species for the tourniquet method include
cedars, junipers, azaleas, and wisteria.The ring method involves using
a sharp knife to cut a ring around the diameter of the branch and then
remove the ring of bark. Make sure you remove the bark and the
cambium, leaving just the tree's "shiny" hard wood or the tree will
not grow new roots. You can dust the ring with hormone, found at
bonsai specialty shops, and wrap it with moss or plastic wrap.
Japanese maple, Chinese elm, and cotoneaster do well with this
technique.Your goal with either type of layering is to force the tree
to send out new roots. They will be easier to see if you've used
plastic and not moss. It's important not to remove the branch from the
parent tree too soon. Once you can see a mass of roots, or root
ball-usually within three-to-six months, you can cleanly cut off the
branch and place the root ball in a pot filled with peat most. Freshly
potted air-layered plants should be placed in a damp, humid area and
misted regularly.Grafting is a complex method that involves combining
two plants-either two parts of the same plant-or of two different
plants. This is done by exposing the cambium, the layer under the
bark, and joining the two parts together and allowing them to heal or
graft together. The cambium of both the transplanted plant, or scion,
and the rootstock or under-stock (plant which interacts with the soil)
must be kept in contact with each other for several weeks for the
graft to take place. The scion is usually a short piece of stem with
one or two buds, and the rootstock will become the new root system.
Generally, the closer in species two different plants are, the better
the chances of a successful graft.