IME, N.Stellata whether green or red will grow much more compactly under good lighting. If the lighting is low the leaves search for the surface in order to get more.
You are supplying excellent light. They like it where they are. Be happy......they can be a PITA when light limited.
Len
You are supplying excellent light. They like it where they are. Be happy......they can be a PITA when light limited.
Len