I think honestly it wouldnt be worth the trouble. It would seem too complicated to be feasable. Greenhouses are not that easy to keep within a range of temps without some sort of complicated control system (SOmeone who knows more than me on this one, please contribute!!!). It would seem to me that if the temps fluctuated too much, ALL the frogs would die, and depending on which way it fluctuated or how much, all your plants might die too. That would suck.
How would you monitor their food intake? There are no doors for humans that I can think of that have a small enough gap around to keep IN a dart frog.