posted on Mar, 10 2009 @ 02:30 PM
I have a lot of greenhouse experience, and live at 7,000 feet in CO (which is why I have greenhouse experience, lol).
The type of greenhouse you are using, is simply not suited for your environment.
The fitted plastic types offer zero insulation as far as temperature goes. What you need is a more traditional greenhouse, and a lot of thought has
to go into how it's set up. Different glazing (the "glass") materials have different R values, your fitted plastic being as close to zero as it
I'd recommend a triple wall polycarbonate, clear, with a minimum thickness of 10mm. this will give an R value of approximately 2 - 2.5.
Framing material is another factor. Aluminum is horrible in cold climates, unless it's an air-gap type of construction, where the frame exposed on
the outside, makes zero contact with anything exposed to the inside.
Location location location... Make sure you're taking full advantage of your sun.
Flooring... What type of floor do you have? What type of foundation is this floor set upon. Here in Colorado, I even have to insulate my foundation
from the earth that surrounds it. You want a floor that will provide you with a decent amount of passive solar heating. Something that will store
the heat from the day, and give it off during the cold of the night.
Believe it or not, water substantially outperforms concrete, pave stones, etc. in this respect. Get yourself a 55 gal. drum, fill it with
water, and just leave it in the corner, out of the way. You'll be amazed at the stabilizing affect it will have on your inside temps.
If you post a few more details about your greenhouse, as well as the orientation to the sun, maybe even a picture or two, I can probably help a bit
more. My entire greenhouse is hydroponic, so I can also monitor and adjust the temperature of the water/nutrient solution that interacts with the
plants roots. You'd be surprised how hardy vegetables can be when they have warm roots. Something to consider, as often making your greenhouse
viable in the winter time, will turn it into an oven in the summer time.