by Midge Goeth

During our garden tour this year, I had asked several members to give me ideas on what to do with a Trident Maple that was in the "training area" of my garden. The main concern for me was a trunk that divided about eight inches from the ground. Earl Cormney suggested air layering and dividing. Because I looked at him as if he was speaking a foreign language, he explained, in brief, what that entails. It appealed to my sense of adventure and desire to learn something new, so the following interview is a result of my inquiry.

GLBS - Earl, tell us a little about your interest in bonsai. I have known you through GLBS for at least fifteen years, so I imagine your experience goes back further than that.

Earl - Actually I started in the club my first year with bonsai. I remembered my wife had expressed a fascination for bonsai but never had one. That year, 1990, for Valentine's Day I decided to buy her a bonsai instead of roses -- figured it lasts longer. So I bought a small evergreen in a green glazed pot with a statue of Buddha and glued rocks on the surface at a local nursery. Not knowing anything about bonsai I thought it was cute and she would find it adorable. Within a couple weeks I thought I would like to know more about bonsai and found my way to the Bonsai Store in St. Matthews. Tom and Helen McCurry told me about the club and everything wrong with my wife's little tree. I quickly joined the club and have been addicted to bonsai ever since. I like to remind my wife, Martha, that this is all her fault. Actually we still have the tree, although many others have come and gone.

GLBS - Let's talk about air layering and dividing. When did you first try the technique and what prompted your interest?

Earl - I read about it in different books and articles in Bonsai Today and thought I would try it one day. I was at first intimidated about completely girdling a tree. My first plant I tried it on was a Cotoneaster. Feeling apprehensive I didn't make a large enough wound and it simply calloused over making a very ugly wound. Since then I have been much bolder and have had excellent success with deciduous plants. It can be accomplished on evergreens but deciduous trees, such as maples and elms, only take two or three months to complete.

GLBS - What do you look for in a tree to complete a successful layering? Are you trying to produce from a single tree one that looks like it has multiple trunks, or starting a whole new tree?

Earl - Usually it is for propagation. Imagine buying a tree for landscape and layering three to five bonsai from the same tree. I might have a particular maple I like because it has small leaves or a great fall color and want more. Seeds will take a long time and offspring do not always have the same characteristics of the parent plant. Cuttings take years for a trunk to develop. Layering can be accomplished in one season.

You can do multiple trunks by layering just below branching. Most of my trees are single trunk, my own preference.

GLBS - Is layering usually done with new, say four or five year old stock, or older larger trees?

Earl - Any age tree will work. Plants in landscape have been very easy to complete, even doing several layers on the same tree simultaneously. Of course the larger the branch layered, the larger the tree once layered. For trees in pots it can be done as well, but it does put more stress on the parent plant. I would prefer to place the parent either in a large growing container or in the ground.

GLBS - Without getting too much into plant physiology, why does air layering work?

Earl - You are disturbing the natural flow of nutrients and water through the tree. The cut stops plant nutrients from the leaves going to the roots. These nutrients feed the roots that will form at the upper section of the cut. Water can still reach the leaves of the layered plant from the established roots through the trunk and into the layered section.

GLBS - Can you give us some basic steps in the process?

Earl -

1. Draw a line around the branch (using the term branch but the trunk can also be layered) and visualize what that new tree will look like once the cut is made. This line will represent where the roots will emerge for the new tree. This line can be slanted to create a tree that leans to one side. Remember it is easier to remove branches than create new ones.
2. Make a pot for the new layer to grow roots. To make a pot, use a discarded 4 inch nursery pot, slice down one side and cut a hole in the bottom the same diameter as the branch being layered.
3. Next, roughly measuring the thickness of the branch, draw a second line BELOW your first line. With these two lines in place, remove the bark and cambium (green) layer all the way to hardwood. If the cut is not deep enough the plant could callous over the wound and not grow new roots.
4. I like to apply fresh rooting hormone to the upper cut mark. Roots will emerge from the upper cut only, not the lower cut.
5. Place your cut pot onto the layered area. Use aluminum wire to tie the pot back together. Pack the cut area of the branch along with an inch or so above with long fiber sphagnum peat moss. You want the pot to fit snug around the branch to help hold moisture. The long fibers will also soak and hold moisture, and I have been told it deters fungal problems. Do NOT fertilize the branch. You can try foliage feeding or rooting solutions. I like to use plain water so as to not burn the newly forming roots. Remember to water this frequently - it cannot dry out or your new roots will wither and die. After a couple weeks you should start to be able to see small roots emerging. Once the pot has an abundance of roots (enough to sustain the plant), cut the branch from the parent plant and pot. You may want to look at the roots and remove some if one side is much too dominant. It can be planted either in a bonsai container, growing pot, or the ground. I prefer to use a large shallow container (wider than deep) so the roots get larger and grow horizontally across the pot rather than just deeper. This makes for a wider trunk at root level and thicker roots on the surface - both attributes for specimen bonsai.

GLBS - I know this technique requires patience and it may take a couple of years to see results. From your experience, can you give us a basic time line?

Earl - I like to start my layers in the spring and cut the branch from the parent the same growing season. It is easier to winter two separate trees than a layering branch up in a tree. Conifers, according to the literature, take longer, sometimes requiring 1 to 2 years. This seems to complicate wintering without the layer freezing. If I had the right plant, I would try it though.

GLBS - Are there differences in the technique applied to evergreen and deciduous trees?

Earl - Yes. Typically the evergreens will take much longer although the technique is the same. I would start with a deciduous plant first and then try an evergreen later.

GLBS - Will the tree require special care during the process? What about watering, fertilizing, sun/shade requirements early in the process?

Earl - Watering will need to take place both for the parent plant and the cutting plant. Some like to use a plastic bag and enclose the layer while it is attached to the parent. This makes watering more difficult and is why I use the small plastic pot technique.

Fertilizing can take place on the parent plant, but not on the potted layered section. Roots emerging are susceptible to chemical burn from fertilizers. Rooting and cutting vitamins can be used.

Light requirements are the same as those needed by the parent plant.

GLBS - What about soil mix for newly layered trees?

Earl - I like just long fibered sphagnum peat while it is attached to the parent and regular bonsai soil after it is removed from the parent.

GLBS - Should special care be taken during the winter?

Earl - If the layered plant is still attached to the parent, I always protect it as much as possible. This could be wintering in an unheated garage making sure it is watered as needed. If it is a deciduous plant, you can mulch over the layered section.

GLBS - What is the best season for layering and dividing evergreens? What about deciduous trees?

Earl - It is dependant on when the roots emerge and fill the pot. I will remove the plants typically in the fall, spring or early summer. If the roots look really full in July or August, I will wait until cooler temps in the fall. Remember we are really re-potting the layered section. Even though we are not taking roots off, we are still disturbing them and care should be given to the plant just like moving any other bonsai.

GLBS - What is your best advice for someone who wants to try their hand at layering and diving?

Earl - Start with something easy. Elms and maples can be done easily on plants in the ground. Layers started in the spring will be ready by 3 months.

Layering can easily be used to increase the number of your trees for a fraction of the cost of buying new trees with established trunk size. Layering provides even root distribution and can be done on any plant material. Pick a plant in the landscape and give it a try. You will be amazed at how quickly you can add trees to your collection.