Hi, a few months ago, at my father's house in San Diego, I tried my hand at air-layering. Well, I can now see that the roots seem to have grown well. 

Take it now, pot it up and put it in a greenhouse. I took my last two this week. It is 40F at night and not much hope for further growing time this season.

Thanks Jon. Right now it is sitting in my father's workshop. I carefully removed it from the distilled water clamshell I made for it. I will bring it home tomorrow.

When you said to put it in a greenhouse...is that for warmth or for moisture-retention? I was thinking of putting it in an unheated room in the house [which stays in the mid 50s]. Do I need to put a greenhouse type covering over it to retain heat and/or moisture?

My thinking was this: If I wanted to root cuttings, I could do it now, as long as they were warm were moist and warm - so, if I treat the air-layer as a cutting, and keep it in the greenhouse, it should continue to increase its rootmass, just like the cutting was going to increase its rootmass (albeit from zero to something in the case of the cutting). Generally, with air-layers, you are taking a portion of the tree that is still green (not dormant) and which has insufficient rootmass compared to the amount of "greenery". In that situation it is important to limit evaporation until rootmass (and water absorption) catch up.

So if you encourage additional root development, it should be a in good position to really take off in the Spring.

So, thinking the through a little more, if I can root a dormant cutting, why shouldn't I be able to air-layer a dormant branch? I am guessing the the only problem is a matter of warmth - 40F outside is not the same as starting cutting inside at 70F.