You have to use the correct COLOR spectrum for flower. That relates to your useable lumens.

You should not put plants in flower and then take them out. Instead, read about 'cloning for sex', whcih is outlined here:
http://boards.cannabis.com/grow-log/...ml#post1829439
Starting at that post, you can follow the process. Go back to see how clones were actually taken, and the mother plants were ranked.