Answer: Volunteers usually have very deep root systems - larger than similar sized trees grown in pots, so they should be expected to show some transplant stress after being dug. Wilting, even dropping foliage are all part of the adjustment period. They will perk up, though, as soon as the roots become established. Hopefully, they've been planted in an area with similar soil and exposure to the sun. If so, they will establish quickly; if not, they will need even more time to adjust. About the only thing you can do to help them along is to water them deeply once a week (daily is excessive - soggy soils will drive out oxygen and suffocate the roots). Simply water them deeply once each week and they should perk up in a few weeks.
Best wishes with your new aspens.
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