It seems like a good shed to overwinter hardy perennials but not many tropicals would appreciate 33.6 F. What do grow in this Sun Shed?

Through November, I had Siberian Tomatoes that did well. I also had then as well as now kale, leaf lettuces, cilantro, beets, bok choi, mizuna and arugula (rocket). These all do not mind 33.6 F and show growth in the 40's.
It's a nice extenstion of the traditional growing season. ~tom

I wouldn't think you'd need much heat for those (except the tomato). My leaf lettuce, chard and collards are still growing and doing well outdoors.

Right! As you said,I don't have a need for much heat. It's a cold frame. In Feb and Mar I will have many seedlings in it that I am starting indoors. By April, it will be retired until next fall. Excuse me for not growing tropicals. I have no interest.
~tom

Tom, your numbers have been helpful in showing me that a well-insulated and well-designed sun shed can make good use of stored water to affect the minimum temperatures at night. Although my problems fall more in the area of cooling on sunny days than heating on cold nights, I'm happy to get a better understanding of how this can work, from this thread and from your earlier ones.

Other folks here have a lot more greenhouse experience than I do, but I think it's pretty impressive to have outside night temps of 12°F and still maintain an interior temp of above freezing, with no added heat. With your structure and stored water system, if you did want to add heat to keep less hardy plants in there, this would surely reduce your heating costs.

Thanks for taking the time to document your findings, and post them here! As a newbie, I find it very helpful.
Sheri

Sun Shed froze with 31 F. the morning of Jan 4th.

The previous morning was 15 F. This morning was 12 F. Despite mostly sun, the two cold days in a row finally got it lower than 33 inside.

Jan 3, 15F outside at dawn, inside it was 33 F.
Jan 4, 12F outside at dawn, inside it was 31 F.

There was still no evidence of the water with any signs of frost and they measured 37 F. Fortunately, I'm growing only cold hardy vegetables so there is no loss.
~tom

Tom,

I appreciate you documenting your indoor/outdoor temperatures. I know you've explained that you have more of a shed than a full fledged greenhouse.

My greenhouse is built rather solid with quite a lot of insulation in between 2X6's. I've been closely watching your statstics as I'm certain I will see similar results...perhaps just a bit colder outdoor temperatures.

It's amazing how long you've been able to keep the temperatures above freezing.

Tj

Tom, again, great stuff!

At my next home, I'm going to have the regular GH for the tropicals. My lychees (blooming right now) and my bananas and papayas won't really like those temps under 40F. But I intent to build a second structure like you have done for other stuff...cold hardy veggies but also for stuff that needs some dormancy like the figs.

Any bug problems at those temps?

No bug problems at all. And to all: thanks for the encouragement. I think I'll add some heating cables to warm the root zones. If I do, I can transfer the indoor sprouting that I start about now and continuing thru March to the sun shed. Any thoughts on continuing with no added heat but only a heating cable under some of my beds?
~tom

tom_n_6bzone,

"Any thoughts on continuing with no added heat but only a heating cable under some of my beds?"

Start petunias, violas, pansies, cauly, cabbage, brussel sprouts etc and onions.

Once you get them going they can survive a nasty frost.

Look over in the winter sowing forum. The stuff they do there once germinated will survive below 32F in your structure.