What you can do is try to tie down your other plants and wait for the other ones to grow in, or in other words:

Bend your older plants so that hieght is no longer an issue; leave the small ones to grow and when they are ready you can start to flower them. I'm sure TriCreator or GKnowm might have something better to suggest but that is my suggestion.
Savage Nature Reviewed by Savage Nature on . Some small some big to early to start to bloom? hey all I have a question, i have a few good plants going, and few not so good, well they are fine just havent had enought time they are a few weeks younger then the larger ones., i need to start sexing my plants that are ready, they few are now about 7 or 8 inches tall, can i begin sexing now, or should i wait 2 weeks, i am running out of room highth wise.... and on a side note, Sonic Bloom works great, comparing my plants to some others i have seen, and on this site, they are larger and Rating: 5