Originally Posted by farmergiles

Pics?

How old were they before you changed the light schedule from veg to flowering?

Anyway, if some of them were showing preflowering then the others probably weren't far behind. I wouldn't worry. You`re right about your concern for headroom IMO.

You shouldn't have to stake indicas at this stage- sounds like they`ve stretched for some reason. How close was the MH to the plants? 400w should be plenty. what size pots are they in?
4`x4` isn't loads of space for 15 plants.

If they're wilting when you water them then they're probably getting overwatered. Keep the soil moist but not soaking.

I`d say you should be able to determine sex within 2 weeks of putting them under 12 on 12 off lighting.

P.S. Please use paragraphs .