DIY Greenhouse Underground

A trench runs down the middle of this DIY greenhouse for any climate.

| January/February 2014

DIY greenhouse

The trench inside this greenhouse forms a heat sink during the day, while concrete block walls release heat at night.

Photo courtesy FARM SHOW Magazine

Dean Steward built a 14-by-24-foot “in-ground” DIY greenhouse for just $120. He simply trenched out a walkway between ground-level beds, walled it with concrete blocks and covered the beds with cattle panels and plastic.

Steward laid out his DIY greenhouse with two 24-by-4-foot beds separated by a 3-foot-wide trench and two waist-high block walls.

“I used a backhoe to dig out the trench and laid the walls without mortar,” says Steward. “I drove rebar into each cell and rammed earth in to fill them. It has been more than a year, and they are holding well.”

He added concrete block steps at one end and built end-walls out of scrap lumber. For the roof, Steward drove in two lines of wood stakes, 10 to a side and 12 feet apart. He fastened 16-foot-long, 50-inch-wide cattle panels between the stakes and covered them with plastic.

“I’m 5 feet 8 inches tall, but with the curve of the cattle panels, I can walk on the beds without hitting my head,” he says.

The trench forms a heat sink during the day, and the concrete block walls soak up heat to release as outside temperatures cool.

4/1/2016 9:21:34 AM

Agree with Karen above, why claim built for $120 when that's absurd. And I'd also like to know how you keep water out of the trench.

6/22/2015 2:13:45 PM

Nicely done. I just finished my cattle panel greenhouse. I didn't do the trench though (way to much work :). It took a better part of a weekend with some good planning and about $300 (not including the shade cloth). I threw up a video if you want to take a look -

10/15/2014 4:15:49 PM

I like this idea. But. I do wish people would post true costs of projects like this. You cannot build this for $120, unless you happen to have most of the materials lying around already and are not counting the cost you already paid for them. 5 cattle panels at $20-26 each, 150' (?) of dimensional lumber, a door or two, greenhouse plastic, 300+ (?) concrete blocks, rebar, hiring a backhoe to dig the trench...

1/22/2014 4:01:01 PM

I need to ask how do you keep the water out and from filling up the trench ? I am very interested in building something close to this....

1/22/2014 9:47:54 AM

25ltr Plastic drums filled with water are a good cheap heat sink and can be used as supports for worktops.

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