Jared, I am no expert when it comes to growing carnivorous plants, so what I will tell you is what I would do growing most any tropical plants.
I am assuming your greenhouse is a really small one and I would raise the humidity there by using humidity trays. You can purchase them or just make your own. You just need a shallow, plastic tray, perhaps with sides 2-3" high, one-half to two-thirds filled with pea gravel. You fill the tray with water, not quite to the level of the pea gravel and sit the pots on top of the gravel. The water slower evaporates, raising the humidity. Just add more water when half of it evaporates. Keeping the greenhouse closed for sixteen or so hours and open for eight hours will hold that humidity in. I don't know whether the greenhouse is large enough to put a small fan inside, but if not, you can place the fan so that it moves air around the plants while the flap is open those eight hours.
This time of year, an eastern exposure won't provide a lot of bright light. A SE, S, or SW will give better light. So yes, put a fluorescent fixture over those plants, again burning the fixture sixteen hours, and letting it be dark for eight hours. Plants need a resting period. I prefer 6500K tubes and also prefer T-5 fixtures. I actually use T-5HO fixtures, but that's way more light than you need.
