Most people harden off plants when they are still in their veg state, still alive and growing, not flowering. Also, plants stop growing once they begin to flower, all the work goes into bud development, your plants right now are not going to get very much bigger if at all, All you gotta do is let the buds fill in, and taking them outside is asking for trouble, what are you hours of light per day right now? Taking them outside could also revert them to veg, and no bud, but most likely the plants will get shocked, and when a plant gets shocked, it stops growing for a period of time if not die.