Roots growing too fast!!!!

How do I get more top heavy cause my roots are out of control. Moved plants from cup to a 3 gallon pot 2 weeks ago. I just noticed that the roots are peeking through the drain holes. Plant itself is still small(10in) some development in nodes. I need more plant growth. Using ffof and Alaska fert. Have a fan on them. Using 32 watt flourecent t8 bulbs. Question is how do I get more plant growth instead of more root growth? I don't want to have to keep on repotting them. Also, should I worry about roots peeking through drain holes? Please help!!!!!