Hi Bob I have done the nirvana N.L. Fem Quite a few times mine usely finish off anything from 22 to 28"inches tall and have found mine go about 65 days in flower, have you done this one before? If so what did you think of the finished product? I actauly like it alot, but have now found another N.L. that i realy like and is very much like the original old school N.L. and that is DR Atomic N.L. but is expensive compared to the nirvana one, anyway good luck with your grow and enjoy when finished. Doby Mick