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Canada

Would covering my Patch number 1 in a blue tarpoline with rocks at each corner ( so it dont blow away) be good enough to help pre-heat the soil before my May 1st planting out in the patch or should the tarp almost be a clear white or black or does it really matter what colour you use?

thanks

Dave

P.S the soil is pretty wet right now so should i let it dry some before covering up or does it really matter?

4/19/2004 7:28:14 PM

let the air get to it until it dries some then work the dirt just deep enough so that it doesn't get hard. If you work it when its to wet it will clump and then get as hard as baseballs, which will not break up until next year after they freeze. black will work better.

Walleye

4/19/2004 11:53:42 PM

Canada

thanks for the info later
Dave

4/20/2004 12:13:11 AM

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I had a four color test going here. The trend was that clear 6 mil plastic raised above the soil at least 1 foot was heating the best. I've abandoned the test for space & patch prep reasons.

4/20/2004 7:48:11 AM

Wichita, KS

Steve, I remember your test. Didn't you say that the 6ml raised 12" kept the air just as warm as your greenhouse?

I would theorize, based on your test, that the clear stuff lets the sun warm not only the trapped air, but it also shines thorugh and heats up the ground as well. The opaque stuff only allows the plastic cover to heat up. Hot plastic would take more time to heat the air, and then the soil, because the heat source (sunlight) is not allowed to reach either.

I say go with clear plastic, Dave, and elevate it a little to trap some air if you can. Just my 2 cents.

Toby

4/20/2004 4:58:13 PM

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The critical element seems to be the trapped air space. The larger the space the better especially on cold nights when radiant thermal losses are large.

I can't say the color matters in this case because we only elevated clear. I was thoroughly disappointed & surprised by the poor results had with the black rubber pond liner. It stayed much cooler than I had expected.

4/20/2004 9:14:44 PM