Esmeralda, are you growing them in some kind of reflecting material tent? Do you have any air movement in there? Maybe a small fan? That one plant looks a little dry, but maybe it is not drying as fast as the others too? Is that one closer to the lights and getting too hot from the lights?

Cory

Make sure you water enough too....but not too much! I have my LED bulbs very close to the trees but not touching so the leaves don't burn. Make sure you have near as much light as possible.

I'm an amatuer, but I was thinking about how a humidifier might help as indoor air is likely to be drier than outside. Some people buy an inexpensive humidifier for their indoor trees.

Loosen those shipping ties. Let the trees move to gain strength.