Well, I've been known to say that if God had meant trees to grow indoors,
She'd have put them there.
I still subscribe to that belief, but my growing collection now includes a few
trees that MUST come inside when temps get to the low 40s.
So, window light and one 28-inch fluorescent fixture is AS FAR AS I'LL
COMPROMISE My "integrity." ;-)

Piffle! You would sing a different tune if you lived on the 43rd Parallel. Did
God intend humans to live in this forsaken climate, with 119" of snow every
winter? Why shouldn't we grow trees indoors?
Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra