Commercial underground greenhouse in Oklahoma

Hi everyone, I have been looking on developing an underground green that can withstand the Oklahoma heat. I’ve been doing a lot of reading about the “greenhouse in  the snow” company. From what I’ve been researching this is what I’ve come up with thus far. Wondering what opinions and ideas everyone has.

First off I have already ordered a 32x80 greenhouse. I wasn’t planning on burying it til now. The greenhouse has three foot wide walls and 6 mil plastic. More specs below.

My idea with the greenhouse was that I would excavate a 6 foot hole large enough to fit the house. On the inside I was planning on using 2inch insulated foam board all along the dirt walls. Those three foot side walls on the greenhouse wouldn’t even be used/open. Next I wanted to install four blower intake fans (don’t know what size I should get yet) on all four corners on the floor of the greenhouse. Each of these blowers would have six, 4inch, HDPE corrugated pipes, that go 8 feet underground and extend 90 feet out then back into the greenhouse. That’s my cold air flow. I would also have tons of oscillating fans pushing that air around.
Next I want to add two 10inch can-fans, located on the top, (still talking about the inside of the house) almost centered in the middle. Each fan has ducting connected to it and sucks out air out from the house to the outside.
That’s my hot air outtake.

For the outside of the greenhouse I have not planned anything special. Having trouble figuring out what would be best. Because the side walls of the green house are prefabricated so I could have the dirt I dig come up the greenhouse three feet. But obviously I wanna bury my greenhouse 6 feet. My hesitation is having the dirt rest on the greenhouse plastic. If I would do that I would put up something on the inside so the plastic doesn’t rip because of the weight of the dirt.



Specs on greenhouse if anyone is interested -

-Bows (Hoops) - 1 5/8" Galvanized Steel Tubing (16 Gauge)

-Greenhouse bows are installed on 4' centers (every 4')

-3 Foot Side Walls - Ground Stakes driven approximately 26" into the ground

-2" Galvanized Steel Tubing for side walls and ground stakes(16 Gauge)

-Triple Purlin that runs the length of the greenhouse and connects the bows

-4 Year Warranty 6 mil Clear, UV-treated Poly Greenhouse Film
(3 pieces to cover the house including endwalls)

Your goal is a good one but you're going to need some serious structure to resist that much soil. Do you have access to slabs of sedimentary rock that you could stack as a retaining wall? More details about your available resources, the soil type, etc would help.

Hi Michael, thanks for your reply.

The type of soil we have out there is an loamy top layer with clay further underneath. The is little to no rocks where I’m at. We would have to haul in slabs of rock. Which I’m not against doing. I like the idea though. I could also buy galvanized steel wall cages and fill those with rocks.

I am looking forward to hearing about this as it goes forward.  Have you checked the summer soil temps where you are burying your lines to find out if there's enough of a "cool reserve" to absorb your greenhouse waste heat?  Because it would be disappointing to buy all the pipes and do all that digging/burying only to find out that they didn't do enough.

I do agree that you may want masonry-level structure below grade to hold back the surrounding soil.  The guy I know who was scheming to build something like this (I believe he abandoned the project, sadly) hauled in a bunch of those huge stackable concrete blocks (like Jersey barriers only roughly cubical) to build his side walls, because he could move and place them with his loader bucket.  

Also I didn't hear what your drainage plan is to keep your greenhouse from filling with water and becoming a frog pond.  If you are on a slope then floor drains draining downslope should be fine.  If you're on the level, it becomes a problem.  Unless your floor and walls are a sealed unit like many local storm shelters, water will find its way inside during the kind of rain events where the water is flowing across the ground in sheets because it's raining down too fast to infiltrate.

Hey Dan, thanks for the input!

I have not dig into the dirt that deep yet to check the temps. I honestly first got the idea when I went into my barn and put my hand underneath the floorboards. It was an 100 degree weather day and when I put my hand under there it was cold! I then stuck a thermostat in that same spot and watched it all summer. It stayed a constant 68-70 degrees all season. That’s when I started doing some research and found “greenhouse in the snow” company.

So where I am placing the green house is on flat land. Not too many slopes where I am at in Oklahoma. To stop rain water from coming down into the house I was planning on installing gutters on the east and west sides of my rounded arc greenhouse. The rainwater would hit the house roll down the plastic into the gutters and I would have the gutters plugged into some pvc pipes and drain into my well. For the inside of the greenhouse I was planning on putting down thick mil weed mat. Same goes for the tubing that goes 8 feet underneath the earth, before I bury them I was going to put weed mat around them. If water somehow got into my pipes then I would get small water pump and stick a hose down there to clean it out. I saw someone with an earth battery green house do this. Looked pretty simple.

I see what you mean about needing a storm shelter quality seal to my greenhouse. Let’s say I build one of those retaining rock walls and only bury my greenhouse three feet into the ground. My greenhouse has prefabricated 3 foot side walls.  I place the rock wall on the outside of my greenhouse. The rock wall would protect my side walls from caving in.  I could line the rock wall with a thick mil weed mat as well. I can overlap the weed mat to go up my greenhouse walls. Think that would be enough? Or should I take it a step further?

So you are creating a greenhouse that you believe will be 'cooler' because its sunk into the ground.

I believe it will be as hot as anything in summer. With the roof the size you have any embedment into the ground will have minimal effect.
Are you wasting cash?

Have you thought of a shade house instead?

Hey John, it will be cooler. People all over the world have made these types of houses and have gotten great results. You’ll see these green houses like these in Arizona, India, Canada, and Alaska. The reason is because the Earth holds a constant temperature 6-8 feet under the Earth. The constant temperature at this depth is usually about 50-60 degrees.

My house will be fitted with 10-12” can-fans.
The 12” will move 1760cfm at one foot, 1500cfm at 10 feet. If I have four at the top with two located on both the north and south end I would be moving a ton of that hot air that naturally rises to the top of greenhouse. Especially with the 24 pipes I will have bringing cool air in I would like to think my greenhouse will stay 70-75 degree all year.

John check out this video on this farmer in Nebraska who grows citrus all year round.

I think this is an interesting idea (climate controlled greenhouse) but I have to say I am not entirely convinced that your plan is entirely without issues. If you live in flat country, and the soil is clay, and you ever experience heavy rainfall - it is going to flood. Depending on how dense your clay is, trying to seal the bottom might not be better. You would in effect have created a concrete boat, and it does not take all that much water to "float" something like that right out of the ground (or more likely break it, so the water can get inside. If you are in the part of the state that gets less rain, maybe just a sump pump would be enough, but I would definitely make that a design criteria. Make all those pipes drain with some slope, and you wont have to be pumping out any stagnant water that gets down in there.

As for reducing temperatures, you should definitely look up soil temperature data for you site. 8 feet is not nearly deep enough to get to stable ground temperature - but the temperature swing is probably fairly modest - maybe 10 or 15 degree or something? Soil temperatures at depth lag behind the air temperatures, so they will actually peak after the summer heat is past. Really though, if you excavate a 32 foot wide trench, the middle is not going to behave as though it is 6 feet below grade. The sun will just heat it up over the course of a year or so, and it will probably be pretty comparable to your usual soil temperatures.

So, have you thought at all about swamp coolers? If you have dry heat, just blowing air through a wetted mesh can lower the air temps by 20 or 30 degrees, and the higher humidity levels will reduce the respiration of the plants. It wont work if you have humid summers, but it is something to consider. You are talking about running a lot of fans anyway, so why not swap some unknowns (soil temp at depth, how much heat is actually going to be exchanged, how long it will take for the soil around the pipes to warm up and stop cooling, etc) for a known principle (evaporating water cools the air). You are going to need a lot of cool air for a greenhouse that size, if it is just a half pipe 16 feet in radius, it would contain something like 32,000 cu ft. One of those 12" fans would give you an air exchange every 21 minutes. A website I found https://www.greenhousemag.com/article/greenhouse-0611-cooling-ventilation/ says you should aim for 10-12 cfm per sq ft of area, so you would want about 20 of those 12" fans going. If you are adding drag in the form of evaporative cooling pads (or the drag of sucking thousands of cfms through a 90' buried pipe) you would need to add about 50%. So you might want about 30 fans.

I also think shading the greenhouse sounds like a good idea, although I have no experience with that.

I can see it works in snow, but how will you keep the heat down in summer.
Surely the ground will simply heat to 100 degrees next to your unit.

I don't know enough about greenhouse design to comment intelligently about yours, but wanted to mention that Sunfinch Greenhouse in Rocky, Oklahoma has a geothermal greenhouse which seems to work for them despite our temperature extremes here in the SW part of the state. Might be worth talking with them about your idea?

Good luck to you and I'm interested to hear more about how it goes.

I'm definitely interested in your progress. I'm brainstorming a similar idea in Alabama. I have sandy topsoil with clay underneath. I have acquired galvanized greenhouse arches that I'm going to use to build it. It's an older model and they don't make all the pieces anymore so hardware will be an issue. I have a spot on a hillside picked out. I was thinking the same issues of runoff and protecting from the ground. I was thinking it might be better for me to dig down, create terraces around it, with maybe a French drain around it. I will be on a hillside so I really just need to divert the runoff water. My main goal was to preserve the sides from wind damage with the berms. Optimally I'll utilize a ram jet aquaponics set up from a steam located at the bottom of the hill. I want to do solar to run fans and lights. I'll be reading other ideas on here but any advice is appreciated.

I know this is older, but I also live in Oklahoma (northeastern OK, near Tulsa)..

You're wanting to retain the cooling properties of the earth, but water is an issue here due to the soil. That's why we don't have basements and stuff like that, typically.

What if you instead did earthbag, rammed earth, earthship tire walls, etc... Providing thermal mass... And then set your greenhouse on top of that.. Building up, but taking advantage of the cooling properties of the earth.

You could also take the angles of the sun into consideration and build shaded area into it.. So that the shaded area (one side of the greenhouse) doesn't absorb the sunlight from the summer sun, but allows full sun in during the winter.

Then you can also run some cooling tubes through your greenhouse, earthship style.. And add fans and windows up at the top to suck out hot air during the summer, but keep it during the winter.

Hope that made sense. Just an idea. I've been thinking about making a greenhouse for some things that don't grow around here..

I'd also put in some water somewhere. Some people use tanks, some use barrels. Also helps stabilize temperatures and moisture in the air. You can rig some gutters or roof run off to collect and take advantage of the free water. Just include filters, so drip lines and stuff don't clog uop.

If you do above ground, you can also try aircrete, which is an amazing insulator and temperature stabilizing medium that's resistant to pests, molds, etc. Also hempcrete. Aircrete is lighter and cheaper, though.

Wish you the best!

Patrick Claffey wrote:Hi everyone, I have been looking on developing an underground green that can withstand the Oklahoma heat.

I know I'm late to this discussion; however, I, too, am interested in building a geo-thermal greenhouse. My thought was to do that part of it to keep the greenhouse warm in the winter.

The way I believe I can deal with the heat is a greenhouse design Leon's Greenhouses (currently in Kingston, OK, but up for sale because Leon wants to retire).

They have a greenhouse that has doors on each end and a triangular shaped vent down the entire top of it that can be opened to let the heat out but not the rain in. Their site is down or I would link to a photo.

I have photos of it on my hard drive, but you can't upload images to Permies.

I thought it was the growing oranges in winter guy who had the calculations for how to determine how much pipe you need by the size of the greenhouse. If it wasn't him, someone else has it online in a YouTube video.

I live in north Texas, and I've avoided building a greenhouse because of precisely these same problems.  My idea about greenhouses is this:  they're not really needed in TX-OK except for six months out of the year.  There's no way to ventilate or shade all that glass enough (unless you use 100% shade, which would also kill plants) to get the temperature down.  Nor would geothermal provide enough cool air to cool it down.  The glass should be removable so the plants won't roast in the warm season.

As for the cold season, lots of insulation is needed.  The sun is low in the sky that time of year, so only (removable) south-facing glass is needed.  The roof could be solid sheet metal with styro sheet insulation (and part of it removable for the warm season, the rest providing partial shade).  I was thinking the north side inside the greenhouse could have stacks of plastic barrels or IBC totes painted black and filled with water.  These barrels could absorb heat from the sun during the day.  Behind them, some cardboard covered with aluminum foil to reflect heat.  Behind that, a solid wall of stacked hay bales to add more insulation and make the wall airtight.  The outside surface of the hay bale wall could be covered with chicken wire and then cement stucco and then waterproofed to keep the bales from rotting.