Knock down version

This was built in sections so I can take it down and store it away in summer. The single layer 8 mil will not keep things from freezing. So maybe next year I’ll try adding a second layer. Now to see if I can get lettuce to grow in February.

What temps do you get at the coldest part of year?  How much sun at those times?

In winter it gets full sun. At night it only stays 8 or so degrees warmer, and we do get an occasional sub zero. I expected better.

Dennis Mitchell wrote:In winter it gets full sun. At night it only stays 8 or so degrees warmer, and we do get an occasional sub zero. I expected better.

Hello Dennis,

It’s only a plastic film, like a camping tent.

For humans a tent is warm because it stops wind chill, but the inside temperature is not much different to that outside.

The same goes for the lean-to you made. It would require double or even triple glazed glass to retain sufficient heat, not counting the cold that creeps in via the ground. The day/night temperature variations could be extreme without that type of insulation.

I suggest your ‘poly tent’ would probably be good for early Spring conditions when cold-snaps can suddenly occur and kill potted seedlings. In that scenario it would give you a very nice head-start to getting plants sprouted and hardened-up before the ground outside warms enough for planting in the garden e.g. a real boost for successive planting – maybe allows to get one or two extra crops in for the growing season.

Where do you live?  I'm guessing it gets pretty hot on a sunny winter day.  Are you often sunny in winter?  

In the second photo there's a healthy sized gap between the rocks and the front panel.  That could let in a lot of cold.

It will be hard to store much heat in that space to make it through a long winter night.  The building will give off some heat but the the glazing will bleed it out faster.  Some additional thermal mass could help.  Frozen ground outside just freezes its way under the walls and now you have frozen soil inside.

I’ve stuffed hay in the cracks and added a water tank. I’ll use it as a cold frame, for now. It also has the dryer vent feeding into it. Not at all sure how that will work. I’m in a very dry environment so I’m not worried about humidity....yet.