Has anyone tried doing air layers while the tree is dormant? Its been in the 70s here all week so it got me wondering. Does it work?

The leaf provides the rooting energy,no leaf,no rooting.The best time to place them
is just as the buds are breaking leaf.

I did one this fall season on one of my trees as it was going dormant. It's over two months now and still no sign of any roots.
I'm thinking that rooting activity will pick up when the growing season starts again.

Makes sense.. this weather has got to be throwing off the trees. I'm already seeing green tips on my Celeste!! My luck we will get a late freeze.

I have to disagree. My leafless cuttings are rooting very well at 60F. You would have to trust that the temps will not go back down or you may end up with tender roots getting frozen and exposing that node to rot.

Your leafless cuttings are disassociated from any root,it knows it's going to die unless it starts it's own.
Not so with an airlayer,all nutrients are still provided via existing root so it has no need to form it's own,
even if you girdle it.Once it leafs out the energy flow from photosynthesis tries to find it's way back down
the trunk and can be interrupted to form root.I'm not saying you can't develop some wimpy root,just that
it's something I've filed under "less than best practice".<G>

Hi,
Just be careful, as you could well have the stem rotting with the unused humidity from the rooting medium.
I have currently a ground-layer that I left untouched because I couldn't find evidences of roots.
The ground-layer is outside and it gets light and air.The tree is dormant, and so is my ground-layer. My plan is to remove it in June ... hopefully .
If yours would be inside a garage... I would fear that you'll end rotting the stem because of the contact with the rooting-medium.
Just wait until April and set it up at that time. Wait for the tree to be outside in the open.

The caveats about too much water are correct but I placed one late fall and it didn't root so I left it on for the winter and as the leaves came out the roots did, too/

In the late summer of 2016, I set two air layers on my in-ground trees. One was set on a 1st year Chicago Hardy and the other was set on a 3rd year Lattarula. I didn't girdle the bark on either of the trees, and I used a light airy peat/perlite mix. By the time the trees were going dormant (late November), I had quite a root ball on both layers. As soon as the trees dropped their leaves, I removed the air layers, and they are now sitting dormant in my basement and appear to be totally green. The CH is only about 1 ft. tall, but the layer I took from the Lattarula is almost 4 feet tall with 3 branches. I was pretty impressed that air layering can work so late in the season in zone 6.

I think I'm going to go ahead and start one just to see what happens. Just not going to let it get too wet. Time to get out the electrical tape and plastic wrap out for the first time this year. If it works I'll let y'all know.

I disagree with the talk about only being able to grow roots from plants with leaves and leaves storing rooting energy.

Leaves are the primary energy conversion system, they turn minerals + carbon dioxide + water into sugar via photosynthesis.  The primary energy storage is the stems and roots of the plant.  All energy stored in the plant can be used to do any of the things the plant is equipped to do, it's all sugar, all of the systems run on sugar and water.  None of that energy is special rooting energy.  Cuttings root because there energy stored in them, then they grow leaves.  This wouldn't be possible if energy storage were focused in the leaves.

You can definitely grow roots from a leafless plant!  

Well,the OP has determined to hang one so the results will be in soon enough.
In the meantime here are a couple of links that explain the mechanic's of
how the process works.Please note the carbohydrates,photosynthates and
auxin (root hormone) referenced are created via photosynthesis which
requires leaf.True,these substances are in storage during dormancy but
their purpose is general health maintenance and to "kick start" the leaf.

https://www.evergreengardenworks.com/airlayer.htm

http://www.gardenality.com/Articles/1149/How-To-Info/Techniques-and-Methods/How-to-Air-Layer-A-Japanese-Maple/default.html

http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1120069862&topicorder=4

http://arnoldia.arboretum.harvard.edu/pdf/articles/2010-67-4-tree-hormones-and-why-they-matter.pdf

This is not a matter of idle conjecture for me,I do anywhere from 100-200 a year.And just for the record
I said nothing of the leaf storing energy.