The yellower the light the better for macro growth. I use a cheap double strip shop light. Others I know use a 6500 MH
or better yet, something lower. LOA (Lights of america) makes a fixture you can buy at walmart for $20!!
I think pruning helps things from going asexual more than anything. If you get spagetti macro you wont have to worry as much about going asexual. Grape has more of a tendancy to go asexual although I have never experienced this. I have 3 types of macro (grape, spagetti, and feather) as I think each one takes out something else