FlytrapCare Carnivorous Plant Forums

A simple electric space heater will work great, but it'll cost you to keep it running if you're electricity is anything like the price of ours.

This is what I'm doing for my non-carnivorous greenhouse. I'm going to stack up five gallon buckets painted black and filled with water on the back wall to act as a heat storage area. Obviously this won't keep the greenhouse from getting cold, but it definitely ought to keep it from freezing.

Water by nature has excellent thermal mass, and this makes it really good for this application. But, considering the drought you've got, IDK if you'll be able to fill all those five gallon buckets. You've got a pretty small greenhouse, however, so I suspect you'll be able to if you start filling now.

Also, make a curtain that you can put over the greenhouse at night. Most of the greenhouse's heat is lost at night. Another thing you could do is put another layer of greenhouse plastic over your greenhouse for the winter to create some dead air space to act as insulation.

you don't really get to cold, so a space heater should work at night and a fan, keep the heater away from water

If it is a greenhouse for highlands nepenthens then you will want a the temps to drop at night. I don't know the exact climate of San Diego but if your winter nights don't drop below 55 F then you should be fine.

I suppose so. The heater shouldn't run you up too much money, as it seems you may not need it every night.

Insulating with bubble wrap ought to take you through winter, but do get a supplemental heater just in case.