1) People dig them up (e.g., permits may be obtained) and usually wrap the roots in burlap and they are sold. Sometimes burlap bags are put in pots and this can be misleading. My experience is it is a stretch to call these (evergreens too, dug up with root ball) actually rooted. In aspen you can actually see it—the (small) tree may look healthy but the root is still in the same chopped-off fashion as when it was dug from the ground.
That the roots appear to be not be established may contribute to the difficulty in planting and establishing.
2) Too old. No, I’m sure it works as it is proven and widespread, but the hydration is not practical for me.
https://ucanr.edu/repositoryfiles/ca2201p14-65352.pdf
http://treesforlife.org.uk/work/forest-restoration-techniques/aspen-propagation-from-root-cuttings/
Aspen can be tricky because they can sell for under $10 or over $150. To do this commercially this appears to be the proven method.
CANNOT FIND IMAGE of the misting machine and process, but.. Putting together a misting process may be possible but combining it with the temperature and humidity (where I live) just is not possible.
These same conditions, where I live, are also great for growing aspen (outdoors).
Last Spring I did try putting some good hearty roots in a pot similar to the picture above. I think I put a layer of roots, covered them with good soil or compost, put another layer of roots and did the same. I remembered this image and general process from research years ago. I left it outside in the late maybe May or June and tried to keep it moist. For a few weeks I watched for leaves sprouting up but I did not see any. Unless it shows signs of life this year (unlikely) and I can find it, it did not work.
3) I’m going to use this (division of roots tab near bottom) as my blueprint:
If only small numbers of plants are required, the easiest method is to dig up some roots in March, which already have young suckers emerging from them and transplant them in the desired location. Root sections should be 2-3 cms in diameter and 40-60 cms in length, to provide sufficient reserves for a new plant to grow, with suckers of 15-60 cms. in height. These could be rescued from an unprotected site where suckers are being browsed and should become established quite quickly.
I have done this dozens of times with a) good success in the ground but b) poor success in pots.
