We live in Richmond, VA (Zone 7a/b). We recently built a small (4x8) greenhouse in our garage to grow tropical stuff (lemons, limes, oranges, dragonfruit, jackfruit and a carolina reaper plant). It is basically stick built with a clear plastic outer covering and bubblewrap inner layer. The floor is insulated with 2" foam insulation. For lighting we have put in multiple grow lights. So far, so good. The last couple of nights, the temp outside has dropped in to the 30s. Inside the garage, it's dropping probably to 55ish? I don't have a good temp on that. I have a small 750 watt heater in there that I have set to come on at 65 and shut off at 75. With the lower temps, it doesn't seem like the bubble wrap/floor insulation/outer shell is making much of a difference. Once it gets to 75, it drop 5 degrees in 30 minutes or so, and drops to 65 within 1 1/2 to 2 hours. Adding the floor insulation and the bubble wrap didn't really seem to help. I've been taping the insulation joints, etc. so I don't think we have a draft or anything so I suspect that it's just radiating thru the walls.
- Any suggestions?
- Is cycling like that normal? I can program it (if necessary) to be not as aggressive during the night (65-70) and be more aggressive during the day but don't know if that is good.
- Is there any concern with deep cycling (10 degree dead band) with plants?

Regards,
Bill