I'm certainly no expert regarding this plant, but mine has sulked all spring long. Mine is smaller, is in a container with fast-draining soil, and needs consistent watering. It put on a flush of spring growth early, but has stopped growing and is wilting badly in our current heat; no leaf drop (yet?).

I am led to believe that this plant is very susceptible to root rot, and well-drained soil is a pre-requisite for proper growth. However, I also believe it can't dry out. Therefore, "just the right soil" and proper irrigation practices are key.

It's my current feeling that the plant is fussier than I am willing to accept, and I don't want to buy any more of them. It does have a very interesting habit that I like, but I'm willing to accept a lesser-quality habit for a more-easily-cultivated variegated tree. Given all this, I've found that Acer negundo 'Flamingo' is more to my liking.

. . . Oh, and more to your point, I would guess that as long as your soil and irrigation are to the plant's liking, the tree should leaf-out again.

I have not had luck with the variegated form but I planted the species in an area that had high shade with some filtered direct sun. The soil is heavy with a slight grade but since the sun never directly shines on the ground there it retains some moisture. In that location the species grew like a weed. It is in an are that cornus kousa does very well also. david