Wouldn't the cooling effects of water diminish the heating effect you're trying to get?

That would be my question as well. I have successfully solarized bermuda grass from two sections of my yard using clear plastic. Wet the soil first, pull large/long weeds, place plastic, secure the edges with lumber or rocks or something. Leave it alone for several weeks to a few months depending on how hot it gets in your environment. I do get an occasional bermuda sprout but I just pull it up.

Is the purpose of the flooding just to hold the plastic in place?

Soil solarization will not help with Powdery Mildew, although it may help some with other issues.
Wet the soil and cover it with 2 clear plastic sheets but do not use water to hold the plastic sheets in place.
Keep in mind that soil solarization is most effective in the southern tier of the United States where there is often fewer clouds to block sunlight.

Here is a link that might be useful: solarizing soil

Great link kimmsr.

Thanks for the replies to my post. I had read in a few articles not to allow water to accumulate on the plastic. Evaporating water would have a cooling effect but was sorta hoping it to have a insulating effect at night. Just trying to find that pie in the sky. And yes, the water was solely to hold the plastic down in this Oklahoma wind. Guess I will just mulch a little thicker and thin those melons and such to where they don't cover every square inch of the ground.

I'm not sure I'm getting this....are you going to put mulch on top of the plastic? If so, that's the same issue as the water. The sun needs to hit the clear plastic so the underlying soil gets heated - a lot. Can you lay old tree limbs or old 2x4's on the edges of the plastic? rocks? soil works well too.

Well marymcp, I appreciate your reply and I agree that mulching the plastic wouldn't work. Last year ,I planted my rye grain around Christmas and got so poor of a stand that I had very little mulch material for the entire garden .The spurge took off and set seed in what seemed like a week. So I let every thing grow out wild like to shade the soil and ended up with powder mildew covering half the garden , also in about a week. I pulled and burned it all , so that enabled me to plant the rye and vetch cover early enough that its over a foot tall now. That should give me enough straw to mulch half the garden for a couple months. This garden is a built up a good foot above the existing soil line with a dike of sorts on the sides so I can flood irrigate . That is where the water on top of the plastic came from . Simple way to hold down the plastic but probably ineffective for my goal of eliminating all those spurge seeds.

You may find this link, about Powdery Mildew, of some interest.

Here is a link that might be useful: Powdery Mildew

Kmmsr's link is correct in saying that clear/translucent plastic is better than glass, but the reason given is incorrect. Clear plastic allows the main share of light to pass through and contact the soil where it is turned to heat (passive solar gain). The dead air space under the plastic then serves as an excellent insulator, trapping the heat and preventing its loss to the air. When light hits black plastic, the light is mostly turned to heat on the surface of the plastic where a very large % is lost to surrounding air - precisely the reason why tinted windows make for a cooler car interior.

Adding water on top of the plastic would be very counter-productive for 2 reasons. It will eliminate the dead air space that insulates against heat loss and the warmer the water gets the faster it evaporates; the faster it evaporates the greater the cooling effect ....... shooting yourself in the foot.

Al

You could try using landscape fabric staples to keep the plastic in place.

FWIW - in a perfect world, a 1/2" air space between the plastic and the soil would be optimal insofar as retaining heat is concerned.

Al

One thing to add: In my experience, solarization works best when the sun is closer to it's height, rather than heat being at it's height. In other words -- center your couple of months of solarization around the end of June (sun's height) rather than August (higher temps, but lower sun.)

Agree - the angle of incidence is more important than ambient temps. From about Father's Day to Independence Day is the period where energy absorption from passive solar gain is greatest (assuming flat ground/ northern hemisphere).

Al

This post was edited by tapla on Tue, Jan 27, 15 at 18:47

For solarization to work the edges of the plastic must be well sealed, with soil. Staples will not work.

I should have been more clear. Bury the edges and use staples throughout the middle of the plastic to keep it close to the ground.

Using staples in the middle would allow heat to escape ands defeat the purpose of laying the plastic down.
as stated in the link about soil solarization, " Any holes or tears should be patched with durable patching tape."

I live in central Oklahoma and have a huge infestation of Johnson grass in my vegetable garden. Has anyone tried solarization to get rid of this pest? It would be worth it to me to not plant in the garden this year if I could get rid of the Johnson grass for good.

Soil solarization may, or may not, help remove Johnson grass, depends on how deep the plants roots go. Beyond a depth of 3 or 4 inches the temperatures may not get high enough to kill off plant roots.