Vegetables Gardening - Growing Organic Vegetables

Here is what we did - because the greenhouse was already in place - and it is working very well. We now have seedlings growing in the greenhouse, and the outside temps were below 0 when we planted.

After installing the geo-thermal system we also installed a second plastic skin on the inside of our walls and roof studs, so the greenhouse has the benefit of the excellent insulation the dead-air space provides. I recommend this for anyone who plans to use it for winter growing.

For anyone building a new greenhouse I recommend you remove 4' of dirt (saving the topsoil for replacing at the end), then trench another 4' down beneath where the greenhouse will be. And replace soil sufficient to have your greenhouse 2' below grade. This will make your pipes between 6 1/2' and 8' below grade when finished, and assure you get the 55 degree earth temperature year-round.

1. Because our GH was already in place we had to remove the West wall of the GH.
2. Remove 1' of topsoil and stacked for later return (would have liked to go deeper, but because it was all hand work we stopped at about 1').
3. Using a DitchWitch with simple adapting plates installed to make the trench 6", rather than 4", we trenched the length of the GH 4' + deep close to the right (South) wall.
4. We installed 4" corrugated drain pipe at the bottom of the trench, starting on the East end, with the pipe sticking up out of the ground more than 3'.
5. The first length of pipe is covered with sand and dirt to a depth of 1'. & tamped down.
6. Loop the pipe back upon itself and run it to the East end again, repeating step 5. Be careful not to kink or strain the pipe at the bend.
7. Loop the pipe back one more time, this time running it up out of the hole on the West end and leaving sufficient length to reach the common manifold at the center of the GH.
8. Repeat several times, with trenches about 18" apart, until the GH has at least one foot of pipe for every square foot of greenhouse space. (ours ended up with 6 lines of approximately 110' for 660' of pipe under ground, and the GH is 18' X 36' = 648 square feet).
9 insulate the pipe as it comes up and out of the ground, so you don't lose the 55 degree temperature of the deeper runs.
10. Replace soil in the trench, tamping it firm as you go, until level with surrounding soil.
11. Repeat across the greenhouse until you have sufficient pipe in the ground.
12. Cut off all pipes on east end at 3' above ground, attach an elbow, and strap to wall.
13. Make a manifold (rectangular sheet metal box) large enough to accommodate all pipes, with 3 each attached to opposite sides.
14. Manifold has 4" holes for pipes, and a top hole to fit a blower.
15. Purchase and install a blower (we used a used, found on Ebay 5 ton furnace blower) on top of the manifold, and include a thermostat and variable-speed controller, to adjust air flow.
16. Minimal supplemental heat may be desirable for extreme cold. We installed a propane heater at the East wall, and the GH temp can be raised 20 degrees in 10 minutes with a low flame. It's great!

We will be moving our citrus trees into the greenhouse this weekend. And we already have seedlings growing, which will be transplanted into the soil in 2-3 weeks.

Good Growing!

Jim Kennard