General | What can I grow in an unheated greenhouse over winter?

I work at a Montessori School in CT and we just got a greenhouse. It will not be heated this winter but I was wondering if we'd be able to use it through the winter. I was thinking about starting carrots in five gallon buckets and nasturtium in pots.

Does anyone have experience gardening in an unheated greenhouse in New England? I would love some pointers! Thanks.

Peg Boyles commented,
Emily, if you've already erected the greenhouse, can you post a couple of photos (inside and out), along with the dimensions? Also describe the site, e.g., Does the structure sit on bare ground? Any overhanging trees?

Many food crops can be nurtured through New England winters in unheated greenhouses or high tunnels, but they all come with caveats.
over 10 years ago.

Alexander Ojeda commented,
I'd build compost piles in the greenhouse and turn them. As you turn them (adding moisture when needed), you get heat and humidity. At the end of the season, you have lots of nice compost!
over 10 years ago.

Alexander Ojeda commented,
Is it possible to keep lots of chickens in there under the tables? You would have their heat, humidity, manure and eggs!
over 10 years ago.

Emily commented,
Thanks for all the great responses. I think I will move the compost tumbler to the greenhouse for the winter. Any tumbler tips are also welcome. I was just told we have a thermal cover for the greenhouse so I will be experimenting with that as well.
over 10 years ago.

I don't have experience in New England or with greenhouses, but Eliot Coleman does. He grows for market year-round in Maine and has written several books about it. It's definitely possible to grow without heat if you use cold frames and/or hoop tunnels inside the greenhouse.

In my climate, venting the heat on sunny days would be essential, even on cold days. Imagine a car parked in the sun all day.

I garden in an unheated greenhouse, though my conditions aren't nearly as tough as yours.

Here's what I discovered to be a great help: adding thermal mass.

When I first set up my 10' x 20' greenhouse I didn't have anything in there to moderate the temperature. I could open or close the doors/windows... and that was it.

I went in there during the hottest and coldest pats of the day and night with a temperature gun and found that I was going below freezing at night and above 100 during the day - way too extreme for my plants.

After some reading on passive heating, I added 8 55-gallon drums of water spaced along the edges of my greenhouse and found that they did an amazing job of moderating the ups and downs, even if I never opened the windows or doors. It no longer goes below freezing at night and will not go above the 80s during the day. Perfect!

In your climate, I'd use black barrels and probably add a few more. The effect is quite noticeable.

Peg- I will take some photos of the inside tomorrow. I added one photo of the outside.

Tanya- Thank you for the suggestion. I will definitely look him up. :]

you probably have time for loose leaf lettuce and maybe baby beet greens

See books written by Eliot Coleman. That is where I started with growing in my unheated greenhouse in winter. Modified what I learned until I was successful. Just keep in mind, cold weather crops for in there. They do the best. Good luck, it can be done!!