Yes, it will work, but it may not kill seeds. It will take a minimum of 6 weeks, is what I've read, to kill diseases and such.

If you use the search function to search the forum you'll find other threads on the topic.

Has Duncan gotten it's usual hot spell during this time? I know Duncan can get much hotter than other parts of the coast.

I would suggest you use black plastic instead of the clear. Also, since veggie season is over, I'd leave the plastic on until planting time next spring as long as it's not a huge area and will become a drainage problem in your winter rains.

Here in our hotter summer, a couple weeks hasn't worked for me.

Next spring, get some cardboard, cover the area, wet it down, and then once it's soggy, cut holes where you'll plant. Cover the rest with grass clippings and voila! A season with virtually no weeds. I had a problem area for years and this worked for me.

Clear plastic allows light to pass and warm the soil directly. The plastic then provides a dead air space to help contain the heat. Black plastic absorbs heat on it's surface and then gives it up to the surrounding air, so the soil temperature will rise much higher when using clear plastic.

We can see evidence of this in another practical application by asking this question: Do the interior surfaces of a vehicle get hotter when the glass in the vehicle is clear, or when the glass is tinted. Obviously, the interior gets hotter if the glass is clear, as would the soil with clear vs black plastic.

The SURFACE of the tinted glass would be much hotter, but that is because the glass absorbs and turns the light to heat, then dissipates the heat into the air, thus eliminating about half of the solar heat gain allowed by clear glass.

Al

Hello Dotty
personally I wouldn't solarize because I think it would lead back to disappointment when weeds eventually reappear, and they will.
I would just mulch heavily with paper, cardboard, shredded leaves straw, hay whatever you have.
Since I've been doing that my weeding is down to the rare occurence as opposed to a daily ritual.
I have seen the light
and that is
success is from being kept in the dark

Me too,
I need to clear an area to heel in 100's of plants just for the winter.
I put the plastic down a couple of weeks ago and I think it's too dry. I'm letting the rain get on it today and will re mow then recover.
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I never did this before either. Hope it works. Good luck to us both
:)Laura

Laura, I'm glad to hear there's another experimenter out there! Yes, I'll share my results and please do so too. Yes, nutsaboutflowers, Duncan has had a very hot spell this summer and one only rainstorm since May. My thoughts are that I would try this until I get the material together for another lasagna bed, then uncover it and put down cardboard, etc. for a lasagna bed. I'll move the plastic over to another area that is infested with bindweed. I really don't expect the bindweed to be killed -- roundup didn't touch it -- but it can't hurt. Thanks darthweeder, I think you are right but since this area is plantless at the moment, I thought it a good time to try solarizing. I keep trying to find an easy way to garden!

well ,good luck in your quest

Is it hot and sunny enough for solarization to work? It's usually best to do it in the summer when you will have a few weeks of hot sunny weather. When I think of coastal BC, hot and sunny don't come to mind, but I may be thinking of just one part of coastal BC.

Since I started this project, we have had 3 weeks of hot and sunny temps in high 70's and low 80's, but today it feels like fall. So I expect my solarization experiment is done for the year. But, I'm going to leave the plastic in place for the time being. We often get sunny weather until October here, so I've nothing to lose. I believe that doing things like this make gardening more fun -- especially if they work.

Those temperatures are probably a bit low for good results from solarization. You really want to do it in hte heat of summer. Black plastic may work for you since it works more by smothering than by heating. It takes longer than using clear plastic with heat, but it can be done in cooler weather.

FWIW - black plastic and clear plastic are equal in the 'smothering' department, but clear plastic has a decided advantage over black plastic when the goal is increasing the temperature of the soil beneath the plastic.

Al

Hmmm. I thought someone somewhere said clear plastic wasn't as reliable as black because you were still giving the weeds light, and if it didn't get hot enough they wouldn't die???

If you really want to experiment, do both, and see which works better for you in your particular climate and yard=:)

BTW I just went out to my area that I'm trying to solarize. I put clear plastic and then black over it for good measure. The one area that only has clear plastic has some nice fresh looking green weeds growing under it. I pulled up a spot where it's covered with both....brown weeds.

I'd experiment =:)

Anyone who doesn't think that black plastic absorbs and transfers heat, drop your drawers and sit on the black seat of a car that's been sitting in the sun for awile.

Greg
Southern Nevada

I hope at least the OP can follow the reasoning and the scientific principle involved. I don't imagine anyone wants to take a stab at providing something scientific to support why they think black plastic is better?

Less than 1/2 (50%) of the heat energy generated by light makes it to the soil when using black plastic as opposed to clear. The rest is turned to heat on the surface of the plastic and is lost to the air. It's not a difficult concept. Do you feel warmer in the sun, or in the shade of a tree? - same principle. Sun hits the leaves - turns light to heat on the surface of the leaves - heat is lost to the air - you're cool under the tree.

Al

I have tried both methods, clear and black plastic. Didn't like the clear as it allowed the weeds to grow beneath the plastic.
I reasoned that black would create suitable germination, but lack of light would prevent further growth. Have used black now for a number of years with good success regarding weed growth.
As an side you might be interested with. Since using black plastic I've had no problems with Potato beetle. Haven't seen a one, which of course I rejoice about all season!

Clear plastic was what I had always heard was best. I just did a simple Google on solarizing soil site:.edu and every .edu site I checked used clear plastic. They also suggest watering first (to steam clean, I suppose). But it needs to be done in the heat of summer, basic clean up of the area first, seal the edges, etc.

tj

Here is a link that might be useful: Hot times

I use black woven polypropylene weed barrier extensively in my gardens, and it's counter-intuitive - while the actual plastic is too hot to touch, the soil below is cool, even cold. It creates an air space between the soil and the plastic, which insulates the soil from the heat of the sun. I grow peas, spinach, strawberries and other cool weather crops in rows with black plastic between, in the full sun.

With clear plastic, the sun rays penetrate and warm the soil directly, and the same insulating effect occurs, this time keeping the warmth beneath the layer of plastic much longer, heating the soil much faster.

Amen

Al

I just came in from the garden after sowing fall spinach and lettuce. With the current heat the seeds might not come up well, but I covered it with black weed barrier...which will shade the soil and keep it cooler I believe.

As far as clear vs black plastic FOR HEAT TRANSFER to the soil, I believe clear wins easily. Course if the heat btus are not there, weeds will sprout under it. The very hottest setup is 2 layers of clear with a 1 inch gap between them.

For myself, I wouldn't solarize.

Dotty,
I re mowed and re covered... and the green patches are turning yellow.
Yes, it's best to do this in the hottest weeks of the yr. BUT, PSSST...the greenhouse effect on the soil works by the hrs the sun is actually on the area.
I once put an empty fish tank( cleaning it after I got rid of fish) on a patch of lawn and killed it dead in just a few days because it was in full sun. I can"t remember what month it was, but I swear it wasn't there very long.
:) Laura

Clear plastic is definitely the way to go. If your weeds are still growing underneath your clear plastic, then it is not hot enough for this method to work for you and you should try another. Al is correct...just think it through. There are clear principles at work here. It is not a matter of "do what works for you." If black plastic has worked for you in the past, that's great, but you are not SOLARIZING the soil, you are simply SMOTHERING the weeds. I just succesfully solarized a large bermuda grass laden area in my front yard using clear plastic and a soaker hose underneath to keep the area moist. The area is completely clear of weeds. Just do a little research...I think UC Davis has a fact sheet out on this. The more transparent and the thinner the plastic, the more successful you'll be.

Sorry for the rant folks. But sometimes there is a right way to do things.

I've been checking my experiment daily and the temp of the soil, about 6 inches down is between 80 and 120 degrees F. Of course, this is in the daytime, and our days are getting shorter. Today it was a bit cooler because there was water on the plastic from rain and I needed help to lift the plastic and reset it. Tomorrow I will do this. I don't know if I should leave the plastic in place all winter, or remove it when our weather turns cold and wet which will be in about a month?? Opinions welcome.

If you're using clear plastic, it won't help to keep it on when it's cold and wet. Clear plastic need heat and sunlight to kill the plants below it. If you're using black plastic, you can leave it on because it's smothering the weeds.

Thanks pb, I'll remove it when the weather cools. Interestingly, today the air temp was 10 degrees cooler than the soil under the plastic. When the plastic comes off, I think I'll top the bed with old manure or leaves, whatever I can scrounge.

Our autumn weather is here now, cool and rainy, so I've removed the plastic from my "experiment". Whenever we have grass clippings I am layering them on the area and have rotovated some of them in. Next, I'm planning to put a layer of shredded leaves and I know we'll have more grass clippings before winter sets in sometime next month. There are no weeds sprouting in my solarized garden YET and the soil is quite warm and friable. It will be interesting to see what the spring brings.