In Ground Greenhouse

I've started a project that I think will turn out good. My idea, which come to find out has been done since the 1800s is to have my greenhouse totally in earth on 3 sides so as to keep a more or less constant temperature during all seasons. I got this idea drom the climate in my basement which is also inground on 3 sides, the fourth side having garage doors to drive into it. The basement stays constantly between 69 to 72 degrees year round taking advantage of the coolness of the earth.

This is the initial dig. Dug it with my front end loader. I have put up 10 foot 4x4s every 4 feet in concrete. Next I have to get 26 16 foot long treated 2x12s to go on three sides.

Here is a potting table that I built ahead of time. The top is hinged so that you can pot up over the stainless sink but it can be brought up out of the way if you need to use the sink only. It also has a tray that fits the sink area while you are potting to keep the dirt out.

What a great idea! How is the sun exposure at your chosen site? I can't really tell from the picture. What will you be using for a cover? We have a polyethylene cover that was only supposed to last two years but has lasted seven years now. Our intention was to switch to glass at the end of two years - our basic kit allows that - but we haven't had the need to do so yet.

We do use a shade cover now. The first two years, we didn't, and I lost quite a few seedlings to those unexpectedly warm days, even though we have an automatic cooling fan. Now, we use the shade cover all year long.

One word of warning: if you decide to buy a greenhouse heater, stay away from Dayton. That thing is a power HOG. We've only used it on two nights this year.

Do you plan to put in flooring, or will you be using earth flooring? We wound up using that silverish fabric that is normally used to protect plant beds from weeds. It's worked great, too!

Our basic kit is 22 x 14. We elevated it by putting in wood at the bottom, as you can see in a couple of my photos.

Lemme tell ya', it was a pain dealing with the city inspectors, though overall they were pretty helpful. At least they passed us.

The open side will face south PB. I am throwing around the idea of running 2 100 foot sections of 4inch corrugated sewer pipe inground and having one end exposed to the underside of my deck and the other side coming into the wall of the greenhouse. A temperature activated attic fan would come on at a set temp and exhaust hot air while puling geo cooled air thru the corrugated pipe. the floor will be pavers to soak up solar during the winter. Front and roof will be covered with clear polycarbinate roof panels. I'm hoping that with the design I wont need heating except for maybe on nights that we have a hard freeze and then I can just put a small electric heater in to bring up the temp a tad. We'll see. I'll post more pics as the project progresses.

Oh what a brilliant idea. I will have to tell my husband about that. He may want to try that, too.

We have two windows that open automatically whenever the cooling fan comes on. It's a pretty neat set-up, but I like your cooling idea. And I think it would work. We thought about a commercial swamp cooler, but decided against that.