That doesn't sound right? How come it still has leaves? It should be dormant now, without leaves, and not under grow lights.
I guess that's -25 in F? That's -3,8 in C. Trident maples can handle that easily (hardiness zone 5-8 ).
But I'm confused. Did you keep them inside all winter ?
Tridents should be repotted in early spring, but if your tree hasn't gone dormant, I don't think I would do that now.
What's the reason for repotting? I understood your idea was not to separate and re-arrange them?
