Air layering is a technique based on the same principles as ground layering, but the technique has been refined in such a way that it can be applied to branches in any position on the host tree. Some trees like wisteria and elm layer readily. Others like pine and cedar are much slower at developing roots.

MATERIALS REQUIRED

In addition to a suitable host tree, you will need the following materials:

Sharp knife
Narrow bladed saw
Canadian Sphagnum Moss
Polyethelene sheeting, thick (clear plastic)
twine
bonsai wire
marking chalk
rooting hormone HOW TO CREATE A LAYER

To make an air layer, first determine an appropriate site. Layer sites can be based on points of convenience or interest. There is no physical limit to the size of a branch that can be layered successfully. Branches up to 12" have been successfully layered.
Convenient sites are those that will be pruned away eventually anyway - to redesign the host tree or reduce its size, perhaps the top 1/3 of the tree is intended to be pruned away. This may make a great shohin bonsai if it is instead layered.
Interesting sites might be areas on a bonsai, or even a yard or garden tree that has unique characteristics, such as:

fast taper
interesting movement
unique species or cultivar
interesting forked branch arrangements, etc. MARK THE SITE OF THE LAYER


Using a piece of chalk, mark a line around the circumference of the branch. This will define the new "soil line" from which roots will emerge. Roots sometimes emerge slightly higher than this point, so take this into consideration.
Mark a second line below the first, completely around the trunk. This line should be positioned at a distance approximately equal to the width of the branch being layered. This line defines the lower portion of the layer. The bark between the two lines will be removed as follows:
Using a sharp knife (Our folding grafting JR-0190 is ideal) scribe a 1/8" deep cut around the upper chalkline. The idea is to completely penetrate the bark down to bare wood. This is usually around 1/8" deep, but on thick- or rough barked trees like elm or pine it can be substantially deeper.
Cut a second line around the lower chalkline.
Using the knife, peel away the bark between the two chalklines. Remove it all the way down to the bare wood, which will be evident by its whitish color. Remove anything greenish between the cuts PREPARE THE SITE


Make sure that the wound near the upper chalkline is cut cleanly. It may be necessary to clean up the cut with the grafting knife. This is particularly important, because this is the point at which the roots should be developing.
You may twist a thick piece of bonsai wire tightly around the circumference of the upper chalkline, just beneath the newly cut edge. This helps to ensure that the tree generates roots rather than simply healing over the wound. It also helps ensure a balanced root system by defining the edge at which the roots will develop.
Swab the area with a liquid rooting hormone or paint on a slurry of powdered rooting hormone mixed with a bit of water.
Drench a handful of moss in water. This should be the long, threaded Canadian variety of moss used in planter baskets, not the chopped fine sphagnum. Pack the region with sphagnum moss and tie it in place with twine or bonsai wire applied lightly.

Add more moss to the region. You want enough moss to enable a rootball large enough to sustain the layered branch. This requires some judgement, but it would be approximately the size of an appropriate bonsai pot for a "tree" of equivalent size.
Wrap the moss with clear polyethylene sheeting. This will preserve the moisture while allowing you to assess the condition of the layer. Tie the bottom of the sheeting below the lower chalkline. The upper end may be left partially open to facilitate watering the layer if you are in a moderate climate. If it is very dry, you may need to seal the top edge of the bag as well and open it occasionally to apply water.
Mark the plant with a plant tag indicating the date of the layering operation

LAYERING

After some weeks you should observe the development of white roots issuing forth into the moss
Do not disturb the layer during this period. The roots need to harden-off into a darker, more mature form.
Rotate the plant occasionally to ensure that the entire layer receives the sun's warmth.
As necessary, water the layer area to keep moisture in the moss. It should be damp at all times, but should not remain sopping wet for long.
The period of time required to create the layer varies with the season and the species. During the growing season a wisteria might fill the bag with roots in just a few weeks and be ready to separate in just a couple of months. A pine on the other hand might grow much more slowly, requiring up to 2 years for sufficient root to develop.TIMING THE REMOVAL

By the time the layer is ready to separate, the bag should be filled with roots that have matured from a pure whitish color to a darker appearance. The branch itself should have grown somewhat, indicating that the roots are functioning properly.
The ideal time to separate the layer is the same as repotting; early fall through late winterREMOVING THE LAYER

In removing the air layer from the host plant, caution should be taken not to disturb the roots, which are extremely brittle at this time.
Using a pruner, cut back the extremities of the foliage on the layer. This will reduce the load on the new roots.
Using a thin-bladed saw such as our JR-0111 Keyhole Saw, remove the entire branch and bag, leaving a generous stub.
Open the bag and remove the poly.
Fluff the rootball just a bit, and plant it in a well draining bonsai soil. #Do not disturb the roots very much or they will break. Do not try to go straight into a bonsai container on the first transplanting. Be very gentle with the plant at this stage.
Tie the plant securely into the growing container.
Update your tag with a record of the date of first transplant.
Next year, when the tree is repotted, the stub may be entirely removed and the roots can be refined to create a more even, pleasing appearance. At this time the tree may be planted in a suitable training or bonsai container.From BonsaiWIKI

:) Your a very good person, I am, well, I know loads more now!!!!!

Hello,
Air layering is the process of removing a large branch or section of the trunk of a tree to create another tree. Before the branch is removed it is girdled, protected with peat moss or other media and the girdled section is allowed to root. After rooting the branch is removed from the tree. This is a very common practice in bonsai to obtain another tree from an unwanted branch or to save a thick trunk section that was going to be removed anyway. Andy Walsh posted a short but very informative article on the physiology of this process on the Internet Bonsai Club mail list. Knowing how a tree forms roots at an air layer site provides powerful information for not only understanding the process, but also a vehicle for answering your own questions and solving your own problems in air layering.
In the process of airlayering, the bark, the cambium, and the phloem layer are removed by cutting away about a 1 inch wide ring of these tissues from around the circumference of the shoot. The xylem however is left intact. This is known as girdling.

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Thanks. :)

huh. I never thought something like air layering could've been possible! Wow...this opens up some new doors. Now, where to get sphagnum moss...

We have this Aligator juniper in the back yard. I wanted to do some air layering on it. Do the same rules apply? I'm sure this will take some time for the roots to grow. How long will this take? Do I want to girdle it or just put some of the moss mixed with some rooting hormone and tie it up. I'm wondering this because of the pitch that evergreens produce. Or is this stopped because of the girdling? On a side note I did this to a weeping willow we have in the backyard and it is doing very well. I will try and post a picture of it in a few days. Although I just cut it and put it in h20 ( knowing how well they respond in this way ) The roots this thing had in just a month...wow. Anyway I will post it progress in a few days and I am open to suggestions on how to style it...warning it's in it's begining stages...haha.

helped my understanding since I didn't have an idea about air layering
Nice post!
thanks

if anyone has any info. on wound mastic (e.g. making,buying,or different mediums) that would be super great!!!!

air layering, i just learned something new today.. :D

If the layered branch cannot be checked daily for moisture content is it possible to use crystals to help retain water?

Ha yay I am now offically a Bonsai Geek! Hi all

Is their any formula to follow on length of time we would need to wait before removing the limb.? Like for instance if I have a black ping, one inch diameter. How long would I wait before removing it and planting it. Or is it a feel as you go type of project.? Then when checking the limb would we be able to remove the wrapping to check closely and replace it if we felt it was too soon.?

Thank you,

I find if i do layerings on thoes that tend to weep saps in the early spring just after bud burst by mid summer i am already potting. My teacher taught me this method but i want to try yours on a few other types I have been watching grow. It seems if it can produce a sucker or weep a ton of sap this works well. I have yet to try any layers on coniferious trees. I have heard thought a tournaquette is best rather than a girdle. Only because they can take a second year to harden of and be ready to pot. I know maples elms and crab apples respond well to a layering right after a budburst has run through. MEaning the first sets of leaves are formed and somewhat mature. Crab apples i do just after the buds swell and start to burst. I have a lot fo success with layering them in this fashion but i bet it is like all other things bonsai and depends on how you feel about more than the tree wiht in reason

Thanks for sharing the experience.. .its a nice concept regarding gardening.

I am very new to the hobby and lives in South Africa. I have started with only a few trees and find this topic fascinating.

I have quite a few big trees in my garden and took pictures of these three trees. Could one consider layering on a branch?

Would layering be an option, and if so, at what level, even if it is just for the fun of it?!