It does depend where your strelizia are from, the dutch grown ones are pretty good quality at the moment but I find that Israeli ones don't last that well.

If it's for competition work I'd be a little wary to be honest. I don't think you should hold out much luck for the celosia if it's the brains variety, but if it's the plumosa you should be fine.

Same as everyone else said, better in room temperature, away from direct sunlight and draughts.