FlytrapCare Carnivorous Plant Forums

Folks will need more information to be able to help you.

What is your winter temperatures...the lows and highs? Your location would help, too.

Is the greenhouse rigid glass/plastic or more of a heavy plastic sheeting material?

You might be able to use something as simple as an incandescent light bulb to generate the light that you need. I would opt for two smaller wattage ones instead of one larger wattage one...the reason is that if one of the smaller ones go out you still have some heat generation. With only a single large bulb, if it goes out you may be in trouble. Put several jugs of water inside the greenhouse if you have the room...they can warm up during the day and will help stabilize the temperature inside the greenhouse.

My low-speed internet connection is keeping me from seeing the large-sized images. I would say, though, with the low temperatures that you experience in the winter you definitely will need a good heating system.

The jugs are simply for thermal mass, you could do the same thing with large rocks. When you say "sheet", do you me a rigid sheet or a more thin, flexible clear material? I think I would add another layer around the outside of the pvc sheet...something that could create a small air space/gap between the pvc sheet and whatever the outside layer is. You could even go so far as to cut pieces of rigid foam insulation to attach to the sides, back, and top of the greenhouse, leaving the front only covered in clear plastic. Make sure you get a good seal so no drafts get inside, whatever you. But don't forget to open it up during warmer weather or every few days to allow some air exchange to take place. Something like a 60 watt incandescent bulb should be able to heat the area inside the greenhouse. You're not concerned with keeping the inside temperature all warm and toasty...just above freezing.