IM working at the psychiatric unit tonight and in my down time found this and thought it would be Awesome if I had more land.

http://www.treehugger.com/green-architecture/build-underground-greenhouse-garden-year-round.html

That is very cool.  I had never seen this type of structure before.

I saw one like that at an old plantation home here in La. It had a glass house over it and was only about 10 x 15 feet. If I dug a hole 6 to 8 foot deep where I live, I'd have a swimming pool.
"gene''

It says the idea is 20 years old but they used to use pits to grow pineapples in Europe over a hundred years ago.  In that case they probably used glass instead of plastic, and heat would have been supplied by decomposing manure. 

It's a cool idea but has some drawbacks. 

It is only cheap if you have free labor.  The cost/effort of digging a 6' deep pit is significant.  Would only work in certain areas with certain soil types.  You are going to actually have to dig deeper than you need because when you get down 6 feet, there is pretty much no organic matter.  So you'll have to add back a foot or two of topsoil/compost/etc.  When it rains, I expect you'd get a pond.  In the humid Eastern US, wouldn't it stay mucky all winter?  Unless you're on a mountain/hill, with very well draining soil, and you can divert rain.

You could probably grow lettuce very well in these conditions.  Maybe root crops.  Don't know about much else. 

I've seen quit a few of these things but have yet to see one filled with productive plants. They still get too hot in summer unless outfitted with some real ventillation. And who knows how cold in winter.

The video showed one with a wood stove which he claimed double as a vent for hot air. Oh ya, maybe his hot air, not that created by the sun. The need for stove says it gets too cold in winter. And that stove pipe is too low and too small to be an effective hot air vent. Hot air vent needs to be at highest point.

Find a real grower who makes one really productive year around and I'll be a believer. Ones I've seen have been from builder types, not growers.

I've run across this design before and in certain places I think it has been a very useful/functional.  I've thought about the principles involved with this sort of structure as they are related to the solar geothermal type of system that can accompany a hoop house or a more significant structure.   As pointed out in the post above, there are some issues to consider - drainage, wall support (you don't want a collapse), excavation costs, etc.    
 
There will be a cost with whatever system one is setting up.   Short term cheap systems end up costing more in the long run because of skin replacement, collapse because of a cheap structure, etc.    Of course there are designs that can be less expensive (short and long run) and that takes some research and creativity.

On my city lot I just have a very inexpensive structure I put together with recycled wood and greenhouse grade uv resistant poly plastic.   No heating, just a spring through fall structure for house plants and fig starts - it mostly meets current needs.   I have however, spent time looking at other options for my "dream" greenhouse if I can acquire land.    Things can get expensive fast...

Here is another option that might be worth some thought.   Here is an old posting http://figs4funforum.websitetoolbox.com/post/show_single_post?pid=1279902821&postcount=32 about this guy in Alliance, Nebraska.    It is a variation on the solar geothermal design, different in that it is just pulling heat from the ground as opposed to a system that actively adds heat for use on a daily cycle.  The resultant humidity control is different also. There is a booklet about this project and other articles and a YouTube video that can be found.   http://newenergyandfuel.com/http:/newenergyandfuel/com/2010/01/22/the-missing-geothermal-technology/ 

Anyway, not trying to send this thread in a different direction.  It was just on my mind since the greenhouse type that you posted is quite interesting and useful if designed well and in a proper setting.  Greenhouses are exciting projects to think about.

Byron (Ingevald)

Picture of my greenhouse today. Most trees just planted last winter.

Apricot harvest starts mid April. Still harvesting grapes, figs, persimmon, blueberries, pluots, and plums. Citrus lasts until stone fruits start.

Haven't seen a pit house this productive but would like to as it's a neat idea.

Nice work Steve

Saw on very similar in WA state growing tomatoes year round. The ground buffers the temps and is good insulation.

Thanks, I had that PDF bookmarked then they changed their site and I couldn't find it again. I'll make a copy this time.

I've been planning to make one of these. I've got the lines laid out but I have just been to covered up with other projects to get to it. At this point it will probably just be a covered ditch to hold dormant fig trees for this winter, but I'll grow it up (or down) as I can make the time.

I have loader and backhoe attachments for my tractor so I can do the work myself.

With the winds we get here an above ground greenhouse is problematic. There was a really nice commercially made greenhouse about three miles from here that got flattened this last spring, and a barn across the street from it. We get weird strait line hurricane force micro-bursts in some fronts. One goes through and there's trees, roofs and barns down all over the place. It's hard to blow down a hole in the ground. If the cover blows off that's not much to fix.

I have a south facing hillside I can dig it into and still get drainage. That rammed earth back wall will be more of a problem. That won't happen this year.

I'll go with a rain gutter grow system or just containers rather than putting topsoil back in for a regular garden. A rocket mass heater would be the way to go for auxiliary heat, if it's needed. I see getting enough vent for cooling as being more of a problem.

I grow in a 55' x 14' pit greenhouse (aka walipini) with wonderful results, and will be starting construction on another 55' x 15' (by 4' deep) tunnel next week.

Here's a link to a short synopsis I put together a while back showing some of the construction of my first semi-pit tunnel and what I grow in it: http://www.greenfingardens.com/p/semi-pit-tunnel-greenhouse.html

People are invariably shocked by how much benefit can be derived from going down even a few feet, especially if using 2 layers of plastic (with gap inflated) for insulation.  Further benefits can be derived from adding large stores of water in the greenhouse and from setting up large external reflectors to bounce extra sunlight into the greenhouse during winter.

Wow. I wish I had more land

well, over here, the water table is shallow in the winter months when it is mostly needed and with the rain we have..this would be more like a mud pit...  I wonder how you stop the rain from going in and the water table from raising?