Answer: I think your curly willows are struggling for several reasons. First of all, since their removal from the water, the trees have been forming more new roots in the soil. This takes a lot of plant energy. Since the plants had poor root systems, the leaves suffered from water deprivation and dropped off. The same reasoning would explain the die-back at the ends of the branches. The move outside was probably a shock, too, as the trees were not accustomed to temperature swings, wind and the full sun.
To help these plants survive, I would move them to a sheltered spot in morning sun. Keep them very well watered. (Willows often grow along stream banks and are water lovers.) Be patient and new leaves should emerge in a few weeks. As the weather settles and the trees become accustomed to being outside, gradually move them to the full sun position. If they are to be planted in the ground, do it once the trees have a nice mass of roots, and keep a careful eye on their water the first two seasons.
Q&A Library Searching Tips