The science of air-layering

River's Edge

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Over those course of two years, I've tried 6 air layers and only had one take. They all seem to be doing the same thing, producing mass amounts of callous but no roots, even after months.

My technique is to girdle the branch, apply a powder rooting hormone to the top cut then wrap spag around everything and cover with plastic.

I wrap the spag really tight, the mass is quite hard and I seal it very well, leaving one small hole for watering.

I'm wondering if I'm wrapping too tight and preventing oxygen from getting to the girdle? Also, how wet should the spag be? I kept it barely damp.

I'm planning more layers the year and would like some success. I'll be working with amur maple and rowen
There are a number of reasons why air layers can be unsuccessful. The term girdling means different things to people. Advice on exact steps to take varies and is easily misunderstood.
1.When making the top and bottom cut it is important to use a very sharp edge.
2.Remove all bark, cambium and some of the wood between the top and bottom cut.
3. if using a gel or liquid hormone product give it a few minutes to soak into the upper cut edge.
4. The media used should be packed loosely to allow for air and moisture mix in contact with roots. Also a finer mix initially works better as it is more likely to keep in contact with new roots. ( smaller gaps to dry out)
My favourite media is pumice fines mixed with chopped sphagnum moss. It works well to scrape the moss across a soil serve screen for shredding. Both hold moisture well and allow for air mix if packed loosely.
5. I allow some escape of water so it never pools or sits in the air layer package. Not so tight wrapping or small holes in the bottom.
6. Timing, your zone looks like a shorter season then mine so i would get advice from the local experts for the best time for maples in your area.
7. If you fertilize in the fall the tree will have greater strength and reserves before the airlayering takes place.
Hope some of these ideas help. Maybe you are already aware of them.
Best in Bonsai
 

leatherback

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should be packed loosely to allow for air and moisture mix
This is where it went wrong.
I read the OP and thought: Why wrap this ightly, I just perpare a container, and fill it with spaghnum and clote the container. Not compacting at all where possible. The substrate should cover the top cut well, and keep it moist. But it should allow for air circulation. As such, it is also important to let it stay moist, not wet.
 

substratum

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Somewhere on this forum I read an axiom regarding bonsai form that goes something like, "Taper is nice, but movement is king."

In the spirit of that, is there a downside to angling the girdle cut to something like 30 degrees, when air-layering, in order to introduce motion to a specimen that is too stout to bend?
 

River's Edge

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Somewhere on this forum I read an axiom regarding bonsai form that goes something like, "Taper is nice, but movement is king."

In the spirit of that, is there a downside to angling the girdle cut to something like 30 degrees, when air-layering, in order to introduce motion to a specimen that is too stout to bend?
It Depends on your objective and how well the air layer responds. If your objective is a slant style and the air layer responds with an even distribution of roots on an angle cut, then the only downside would be the limitation of changing your design. Increasing the angle of the cut can produceuneven results. But then air layers do not always produce even results in the first place. So the reality is that you will end up developing and working with the roots to reach your desired goal. The only question is the time involved.
On the other hand if you wish a formal upright, then taper may be more desireable than movement. So back to the first response, It depends.
I have air layered on an angle and got reasonable results but only some of the time. Not near as often with a straight cut or using wire tightened.
Also, i should mention that I have found i can get more natural results using a Toriki scraper or similar tool as described by Masakuni Kawasumi in the publication " The secret techniques of Bonsai" 2005. This type of preparation tends to leave a more ragged cut without crushing the cells and ends up with a more natural looking display of nebari. The tool essentially tears the edge with sharp irregular serrations. Full disclosure, i made my own tool from an old wood rasp based on the principles described and a picture in the book.
 

Cable

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B: Considered a "ground layer" this is an air-layer at any level that is below the first foliage mass.

I was re-reading this thread since my first two attempts at air-layering are going on now when I stumbled across this statement. Interesting. I had always thought that a "ground layer" was when you bent a branch down to the ground and rooted it that way? Last year I had a winterberry start to root where a low branch had mulch piled around it all summer and I thought that an unintentional ground layer.
 

Johnnyd

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There are a number of reasons why air layers can be unsuccessful. The term girdling means different things to people. Advice on exact steps to take varies and is easily misunderstood.
1.When making the top and bottom cut it is important to use a very sharp edge.
2.Remove all bark, cambium and some of the wood between the top and bottom cut.
3. if using a gel or liquid hormone product give it a few minutes to soak into the upper cut edge.
4. The media used should be packed loosely to allow for air and moisture mix in contact with roots. Also a finer mix initially works better as it is more likely to keep in contact with new roots. ( smaller gaps to dry out)
My favourite media is pumice fines mixed with chopped sphagnum moss. It works well to scrape the moss across a soil serve screen for shredding. Both hold moisture well and allow for air mix if packed loosely.
5. I allow some escape of water so it never pools or sits in the air layer package. Not so tight wrapping or small holes in the bottom.
6. Timing, your zone looks like a shorter season then mine so i would get advice from the local experts for the best time for maples in your area.
7. If you fertilize in the fall the tree will have greater strength and reserves before the airlayering takes place.
Hope some of these ideas help. Maybe you are already aware of them.
Best in Bonsai
Have you ever used seaweed in the air layer pot. I was thinking it may effect auxin levels. I did read through the science post but got a little lost. I saw that seaweed has some hormonal effects. I have a few different layers going now (rooterpot, radialdisc, and colinder). All are with straight pumice. I do like the ease of use with the rooterpot. If they only made them larger. XL For 2 to 3 inch trunks.
 

River's Edge

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Have you ever used seaweed in the air layer pot. I was thinking it may effect auxin levels. I did read through the science post but got a little lost. I saw that seaweed has some hormonal effects. I have a few different layers going now (rooterpot, radialdisc, and colinder). All are with straight pumice. I do like the ease of use with the rooterpot. If they only made them larger. XL For 2 to 3 inch trunks.
I have not considered seaweed for air layering. Personally I would be concerned about salt levels and possible contaminants in the seaweed. Would be interesting to hear if others have tried.
 

wsteinhoff

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Tried my first air layer this evening. It's an American elm with different bark than some of the others around here. It's much thicker. I hope I did everything right. For a size reference that's a quart size bag.
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arreaux

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This is also first I've heard of the foil thing.. and sun damaging the layer.
I'd wonder if anyone can attest to that trick more, nice thing to know.

JM Layer 2.jpgJM Roots.jpgJM Limb.jpg20180617_174430.jpg
I always use foil since roots don't like light.
I recently Layered a limb on our JM that growing over the roof. The branch is 2 1/2" caliper at the layering point.
I took a 6" plastic pot and cut a hole in the bottom, then halved it. After removing the bark and scraping the under wood. I used some root hormone and wrapped a handful of moss. I then filled the pot with my usual soil wrapped in saran wrap. Had a hole in the top of the wrapping for water and a few slits in the bottom. Then wrapped the hole thing in foil. I did this at the beginning of April and just recently cut the branch off and potted it.
 

ConorDash

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View attachment 198063View attachment 198064View attachment 198065View attachment 198067
I always use foil since roots don't like light.
I recently Layered a limb on our JM that growing over the roof. The branch is 2 1/2" caliper at the layering point.
I took a 6" plastic pot and cut a hole in the bottom, then halved it. After removing the bark and scraping the under wood. I used some root hormone and wrapped a handful of moss. I then filled the pot with my usual soil wrapped in saran wrap. Had a hole in the top of the wrapping for water and a few slits in the bottom. Then wrapped the hole thing in foil. I did this at the beginning of April and just recently cut the branch off and potted it.

Nicely done. I basically do all of that in the same way.
I’ve currently got a hazel nut air layer going. I’m not using foil as the pot is opaque and the tree is quite bushy and green, the layer is not in direct sunlight. Shown here: https://www.bonsainut.com/threads/corylus-avellana-contorta.26316/page-9

758F7430-B94F-44CC-A7EF-10E2F505E281.jpeg
 

Les Lonsdale

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Lots of good information in these 6 pages about layering!!! One thing that I did not see mentioned (unless I missed it) is the difference between girdling and tourniquet method. Most people and demos seem to prefer the girdling method, but are there certain types of trees where the tourniquet method is preferred?? What makes the difference? Is it better for slow-rooting species? Could someone expound?
Thanks!
 

Saddler

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This shows my method up until now.
https://www.bonsainut.com/threads/i-wanted-a-broom-so-i-cut-down-a-branch.34398/
Next year I am going to use plastic strainers with a piece of plastic in the bottom to protect the roots close to the tree from drying out but once they get to the edge side of the strainer they will get get air pruned. I am hoping that air pruning will lead to straighter roots, but more even roots around the cut. My reasoning is when the first roots hit the outside, they stop growing longer so the *energy that would be flowing to the tip ends up going to the side of that root and into new roots. Just like when you trim the top of the tree, you get new shoots along what is left on the branch and back budding on the rest of the tree.

What makes me happiest about my method so far is that I cut it off so close to the roots that I can put it directly on a board a la Ebihara from day one and I won’t have to spend an afternoon chomping away at the deadwood underneath the tree at the next repot. It can heal and I won’t be cutting it away to get at the dead wood meaning it is losing less energy to rehealing. I think.
 

Johnnyd

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Introduction
Air-layering as a way of propagating bonsai material that has some unique advantages. First, the material being layered is a genetic clone of the mother plant. Second, you can often be successful layering mature and large material that cannot be successfully separated via any other means. Third, layering will often create a ring of fine surface roots that yield an excellent nebari in a short period of time.

Because of the number of questions regarding air-layering on the site, I have attempted to pull together an overview of the science behind air-layering which will directly lead to a list of "best practices" and "frequently asked questions". I am going to try to keep the science really simple (because it gets extremely complicated very quickly) while at the same time ensure that everything I write is scientifically grounded.

Background
All plants sense and interact with their environment. Survival and growth is critically influenced by abiotic factors including water, wind and light. If we understand how a plant senses such factors, and how it translates them into optimal physiological or growth responses, we can better guide the development of our trees. Hormones play an important role in the internal signaling that brings about environment responses, and are keyed in many ways to the environment. Precisely regulated responses to the environment not only allow a plant to survive from day to day, but also determine when a flowering plant will produce a flower, or when a tree will produce roots or buds.

Hormones
Hormones are chemical substances produced in small, often minute quantities in one part of an organism, and when transported to another part, they can bring about physiological or developmental responses. They can both stimulate a response, or inhibit a response. They can work by themselves, or work in concert with other hormones. How they act in a particular instance is influenced by both the hormone(s) and the tissue that receives the message.

In animals, hormones are usually produced at definite sites, usually organs. In plants, hormones are not produced in specialized tissues, but instead, in tissues that also carry out other, usually more obvious functions (like roots, or leaf buds).

There are seven major kinds of plant hormones, but for the purposes of air-layering, we are primarily interested in two: auxin and cytokinin. But we'll get back to these later.

Translocation
Before we start discussing the action of the two hormones mentioned above, we need to review the concept of translocation in plants. Translocation is the movement of materials from leaves and roots to other tissues throughout the plant. Plants create carbohydrates in their leaves via photosynthesis, but other non-photosynthetic parts of plants also require carbohydrates as well as water and nutrients. For this reason, materials are translocated from sources (leaves or roots) to sinks (which could be flowers or nuts or stems). Parts of the plant can be a source of one material (roots absorb water) and a sink of another (roots consume carbohydrates). To facilitate the movement of materials around a plant, there are specialized tissues called the xylem and the phloem. These tissues are made of long continuous strands of specialized cells, and extend all the way from the roots to veins in the leaves. The xylem carries water, nutrients and hormones from the roots all the way up to the leaves. The phloem carries carbohydrates and hormones from the leaves back down the tree all the way to the roots.

In the case of a woody tree, the xylem is the "wood" of the tree, and it consists of older, inactive heartwood, and the part of the xylem that still actively transports materials called the sapwood. The phloem is the living layer just below the bark. Separating the xylem and phloem is the vascular cambium - which generates new layers of xylem in the interior of the tree (making the tree thicker) and also new layers of phloem under the bark. The vascular cambium is the part of the tree trunk that heals damage to the trunk.

View attachment 139462

Ok so I know this is getting a little complicated, but in simple terms think: sapwood carries water, nutrients and hormones up from the roots, while phloem carries carbohydrates and hormones down from the leaves.

View attachment 139463

So let's get back to the two hormones we introduced earlier in this article: auxin and cytokinins. These are both "growth" hormones, but they each trigger different responses in the tree based on their presence and interaction. It is important to note that even today (2017) we are just beginning to understand many of the actions of these growth hormones at the cellular and molecular level, and how hormones regulate growth and development.

Auxin
Auxin acts to adapt the plant to its environment in a highly advantageous way. It promotes growth and elongation of cells, and triggers root generation when it is present in certain concentrations. It will migrate away from the presence of light, and will generate stronger growth on the shady side of a plant - which is why plant stems will bend towards light if only lit from one side. Interestingly, the presence of auxin suppresses bud development. Auxins have other impacts on growth and development depending on the presence and concentration of other hormones. These impacts are usually species specific.

Auxin is generated naturally in a plant at the branch tips (apical meristems) in the buds, and secondarily, in the roots. In its natural form it is known as IAA (Indoleacetic Acid). From the tips of the branches and the tips of the roots, auxin will travel towards the base of the trunk.

Synethic auxins such as NAA (naphthalene acetic acid) and IBA (indolebutyric acid) have been discovered that generate a stronger response than IAA. They have many uses in agriculture and horticulture, and can be used to prevent premature fruit drop in trees, hold berries on holly, or induce root formation in cuttings.

It should be noted that while one range of auxins can have a positive effect on plants, too much can have an extremely negative (if not fatal) impact. Synthetic auxins are routinely used in weed control products, where they are applied in higher concentrations than IAA would normally occur in plants. The herbicide 2,4,5-T is a synthetic auxin that was a component of Agent Orange.

Cytokinins
A cytokinin is a type of plant hormone that, in combination with auxin, stimulates cell division and differentiation in plants. Unlike auxin, most cytokinin is produced in the root tips (apical meristems) and transported throughout the plant. Cytokinins, working with other hormones, seem to regulate growth patterns. They promote growth of lateral buds (while auxins suppress them).

View attachment 139469
(in this graphic, image A shows lateral buds being suppressed by auxin generation in the apical meristem (branch tip). B shows how, when the apical bud is removed (and auxin generation reduced) the plant sprouts lateral buds. However, if an artificial source of auxin is applied, as in image C, bud growth continues to be suppressed.

Conversely, cytokinins inhibit the formation of lateral roots, while auxins promote their formation. It is this balance between cytokinins and auxins that determine whether a plant will favor root development, shoot development, or undifferentiated cells. Lots of plant buds (lots of auxin) and minimal roots (less cytokinin) and the plant will favor root development. Lots of roots (lots of cytokinin) and few buds (less auxin) and the plant will favor shoot development.

View attachment 139470

Air-Layering
Now, let's put it all together. Remember what we learned about sapwood - which carries water, nutrients and cytokinin up from the roots. Then we have the phloem - which carries carbs and auxin down from the branch tips. When we air-layer a tree, we are interrupting one of these flows, while keeping the other intact, in order to trigger a specific growth response in our tree.

I will assume people know the process of air-layering, in general. You start by "girdling" the tree, which means that you move a strip of material entirely around the trunk or branch that you wish to layer. You want to ensure three things: First, that you completely sever the phloem, which will cause a break in the flow of carbohydrates and auxins down the trunk/branch. Second, that you completely sever the vascular cambium, since this is the healing layer of the trunk. Third, that you keep the sapwood more or less intact, since you want to continue to provide water and nutrients to the upper part of the air-layer.

View attachment 139525

As soon as you girdle the tree, auxins will start to build up at the location of the wound site. Additionally, the vascular cambium will respond to the wound by generating a special type of fast-expanding non-discriminant growth cell that will form a callus, which will physically protect the wound site and try to close it. Finally, the level of auxins below the girdle will start to drop because they are no longer being supplied via the upstream phloem.

View attachment 139526

Within a short period of time (as soon as 48-72 hours, if all conditions are optimal) the auxin level above the wound site will reach the level where the balance between auxins and cytokinins shifts decidedly to the auxin side. Because of the elevated presence of auxin in the area, the activity levels of all cell functions are elevated. Cell growth is stimulated, but instead of general non-discriminant growth, the tree is being signaled to generate roots. Meanwhile below the girdle, as auxin levels drop, the auxin/cytokinin balance shifts to the cytokinin side, and the tree is being signaled to produce shoots and develop buds.

View attachment 139527

Because the sapwood remains in place, the roots can continue to supply water and nutrients to the upper part of the layer, which is actually in very little distress.

Once an adequate volume of roots has grown at the top of the girdle, the layer may be separated from the parent tree. Usually this is accompanied by two effects - first, the reduction of water, nutrients and cytokinin from the established roots in the parent plant (via the sapwood) will cause a short term drop in shoot development. This will be accompanied by a short term push in root development in the layer due to elevated auxin levels. Once the roots develop to the point that they balance the upper part of the layer, cytokinin levels will rise, auxin / cytokinin balance will be restored, and growth levels will balance in the layer/new tree.

Image: Girdling a Chinese cork elm.
View attachment 139536

Image: Root development at separation of the layer from the parent tree (33 days after girdling).
View attachment 139537

Image: Root development one year after separation (after minor trimming and raking). In the case of easy to root species like Chinese elm, the development of roots may be so robust that they extend from the wound site to some distance above the wound - projecting through the bark in places.
View attachment 139538

Best Practices
When girdling, make sure you cut all the way through the phloem and the vascular cambium to the sapwood. It is better to even scrape into the sapwood than to fall short and leave strips of vascular cambium behind. Even a small layer of vascular cambium cells can quickly heal into a bridge between upper and lower parts of the girdle, restoring flow to the phloem and preventing the accumulation of auxin above the girdle.

Cover your air-layer location with aluminum foil. Because auxins migrate away from light, there is a possibility that allowing light to shine on one side of the girdle may suppress root development on that side.

FAQ
Q: Is there a best time to air-layer?
A: Yes. The best time to air-layer is during late spring / early summer when new growth has hardened but while the tree is still in growth mode.

Q: Should I defoliate / prune a branch before air-layering it?
A: Generally no. Because auxins are generated at the tips of the branches, it is best to leave as many apical buds as possible.

Q: Should I use artificial auxin on the upper edge of the girdle?
A: Usually not required, as long as the airlayer has a lot of healthy growth (and buds) above the girdle. Will not harm your airlayer attempt, regardless, as long as you don't use too strong of an auxin concentration.

Q: What concentration of artificial auxin should I use?
A: Depends on the species of the tree. I recommend further research, or reference to Dirr and Hueser's The Reference Manual of Woody Plant Propagation.

Q: Is it better to use sphagnum moss or bonsai mix in the air-layer?
A: Whichever you personally prefer. The function of the propagation mix in the air-layer bundle is simply to prevent the new roots from drying out. It serves no other functional purpose, since the water and nutrient needs of the air-layer are still being met by the translocation flow in the sapwood.

Q: Can I do more than one air-layer on a tree at a time?
A: Yes, but you should only try to air-layer a branch that has an uninterrupted path to terminal buds. In other words, you can air-layer two branches next to each other, but do not try two air-layers on the same branch (directly above and below each other).

Q: After I separate the air-layer, should I prune the branches?
A: It is better to leave them unpruned, since the branch tips are providing auxin to continue to develop the new roots. If you need to protect the foliage until the new roots increase their capacity to provide adequate water, you can use a humidity tent over the tree. The sign that it is "safe" to prune the tree is when you see it start to pop new buds and push new growth.
I have an air layer on a cherry blossom tree in a rooter pot. I can see a lot of roots extending into the bottom reservoir of the pot. Recently this week the leaves on the branch being layered are drooping. The tree itself is a landscape tree. All the other leaves look normal. I'll add a picture soon. Any ideas would be greatly appreciated. I have chopped sphagnum moss in the pot. I have been watering every few days recently. The branch diameter is about 3/4 inch.
 

0soyoung

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Trees compartmentalize damage (CODIT). With girdling a branch we create a circumstance that is much like having pruned off the branch at the point of the girdle. After some time, insufficient auxin exists for the cambium to continue living just below the girdle/pruning cut. Its dying act is to send out a chemical messenger to seal the xylem. If this is happening to an air layer, you will have symptoms like you describe - leaves will wilt, wither, and turn brown progressively moving upward from the girdle toward the branch tips. Usually this can be verified by examining the bark at the bottom edge of the girdle - it will be discolored to blackened, soft and squishy, and possibly slippery.

If this is the case and there are not yet any adventitious roots, there is, for all practical intents, no hope as the layer will no longer receive water and minerals from the mother tree. The blockage actually occurs in the layer, above the girdle (because the messenger is carried upward in the xylem sap).

On the other hand, if the layer has already generated adventitious roots, it may survive. However, the symptoms of limp droopy leaves indicates that they are insufficient to support the layer. It would likely be appropriate to remove the layer, pot it securely so the roots won't move in the substrate, and place it in a shady location and maybe even put it into a humidity tent to limit transpiration. Then, the layer may grow enough roots to survive before leaf fall and not die by desiccation.
 

Johnnyd

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Trees compartmentalize damage (CODIT). With girdling a branch we create a circumstance that is much like having pruned off the branch at the point of the girdle. After some time, insufficient auxin exists for the cambium to continue living just below the girdle/pruning cut. Its dying act is to send out a chemical messenger to seal the xylem. If this is happening to an air layer, you will have symptoms like you describe - leaves will wilt, wither, and turn brown progressively moving upward from the girdle toward the branch tips. Usually this can be verified by examining the bark at the bottom edge of the girdle - it will be discolored to blackened, soft and squishy, and possibly slippery.

If this is the case and there are not yet any adventitious roots, there is, for all practical intents, no hope as the layer will no longer receive water and minerals from the mother tree. The blockage actually occurs in the layer, above the girdle (because the messenger is carried upward in the xylem sap).

On the other hand, if the layer has already generated adventitious roots, it may survive. However, the symptoms of limp droopy leaves indicates that they are insufficient to support the layer. It would likely be appropriate to remove the layer, pot it securely so the roots won't move in the substrate, and place it in a shady location and maybe even put it into a humidity tent to limit transpiration. Then, the layer may grow enough roots to survive before leaf fall and not die by desiccation.
Thanks Osoyoung! I included some pictures. I removed some competing branches to direct strength to the air layer. It does not look as bad now. I was wondering if the wire I used in combination with the ring bark method is constricting flow in the sapwood. Maybe as the branch grows it causes a problem. I've noticed in other threads that you do not use a wire when you ring the bark.
 

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0soyoung

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I believe the idea of wire at the top of the girdle is interfere with the downward progression of the callus that inevitably happens. Some claim it deflects the growth of adventitious roots outward, away from the trunk.

It is conceivable that the sap wood could be crushed by over tightening the wire, but it doesn't seem likely. Were this the case, the leaves of the layer would begin to desiccate immediately. New wood is made by division and differentiation of cambium cells. There is no cambium in the girdle - you removed it to make the girdle, so there will never be any radial growth here (or anywhere else that cambium is missing)..

Often one applies rooting hormone (an artificial auxin like IBA or NAA) to the top of the girdle to 'jump start' the rooting process. Applying hormone powder/gel/liquid that it too strong will cause the leaves on the layer to change color and behave as though fall is near. The natural accumulation of natural auxin above the girdle could cause this same reaction to a certain extent. Perhaps this is what is going on with your cherry air-layer, @Johnnyd.
 

Johnnyd

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I believe the idea of wire at the top of the girdle is interfere with the downward progression of the callus that inevitably happens. Some claim it deflects the growth of adventitious roots outward, away from the trunk.

It is conceivable that the sap wood could be crushed by over tightening the wire, but it doesn't seem likely. Were this the case, the leaves of the layer would begin to desiccate immediately. New wood is made by division and differentiation of cambium cells. There is no cambium in the girdle - you removed it to make the girdle, so there will never be any radial growth here (or anywhere else that cambium is missing)..

Often one applies rooting hormone (an artificial auxin like IBA or NAA) to the top of the girdle to 'jump start' the rooting process. Applying hormone powder/gel/liquid that it too strong will cause the leaves on the layer to change color and behave as though fall is near. The natural accumulation of natural auxin above the girdle could cause this same reaction to a certain extent. Perhaps this is what is going on with your cherry air-layer, @Johnnyd.
That makes sense regarding the growth. I appreciate the details about the possibility of using too much rooting hormone. This may explain a recent near catastrophe with my Sharps pygmy. I lost most of the leaves. I thought it might be leaf scorch but it looked more like fall leaves. I am slowly learning the science of air layering. Mostly by making mistakes. Lol
 

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Johnnyd

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Yes.

But roots grown in sphagnum are fragile. I put these in a plastic pot and stabilized so that the roots won't get moved around. Usually I screw a couple of sticks to the pot, opposite one another, and loosely bind the tree to them with some junk wire analogous to the common practice with landscape trees. Sometimes I drive a screw through the bottom of the pot and into the stub at the base of the layer. Regardless, the following spring I remove the sphagnum when I repot (possibly into a bonsai container). If you are layering a portion of a vertical stem (e.g., a trunk), you an fit a pot around it and grow your layer roots directly into your favorite substrate, thereby avoiding this added step to harden the new roots.
So in this case you would not need the 6 week grace period between the first freeze? You can separate after leaf fall if there are enough roots?The Sharps is doing great! The Beni Maiko is still slow. One root and bubbling callous in pumice filled collinder. I used a grafting knife to cut small slices in the callous. Finished with light glaze of clonex.
 
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