Cooking a lasagna bed with black plastic

I have a huge lasagna bed (8x24), that I am afraid won't go down by spring.

I used 3mil black plastic and put it across the bed, overlapping just a little. But any time there is a little wind it gets picked up because the wind catches between the overlaps. We have put all sorts of sticks and boards over and along it to hold it down.

How do you do this? Would it be better to put the sheets down lengthwise to minimize the overlap (but the wind could still get in). Or does it not matter if it is open here and there? Also, it catches water because the bed is quite bumpy.

Any advice or experience?

I suspect that someone has already asked and gotten the answer about this, but I can't find it.

Got bricks?
I have good luck with a scrap of black rubber roofing membrane I salvaged from a dumpster. Carpet works great, too. I don't know if I get the true 'solarization' effect with these, because they're opaque, but it seems to work fine.
My problem (one of many. . ) is I want to kill a big area in the front lawn without the neighbors having to look at it. I'll probably just dig and weed a lot.

There is an inverse relationship between light transmission and solar gain in passive solar applications. The more light striking the soil, the warmer it will become, so clear plastic is much more efficient at increasing bed temperatures.

Practical examples of this principle at work are:

A) Clear lenses, as opposed to tinted or opaque, on solar collectors maximize the heat gain at collector plates (exactly the application you are attempting).

B) Tinted windows in your car help keep the interior cooler.

In applications (including yours) where light strikes a tinted or opaque material, the suns energy is trapped at the surface of the material and turned to heat. Most of the heat is then given up to the atmosphere before it can be absorbed by or turned to heat in the materials on the shaded side of the lense material.

Al

I was thinking the opacity of the black rubber would block light so well that weeds would die, but I guess it doesn't get hot enough to kill seeds and roots. I'll say this for it, it didn't blow around much, and it was free! A big roll of clear plastic's only ten bucks, though.

This site's interesting, it talks about plastic mulch films that block different wavelengths of light for different uses in farming. I'd like to find some small pieces to try instead of thousand foot rolls.

http://www.nevegetable.org/index.cfm?objectid=D5BC1934-8C7F-4CFE-520B8A33160DA88A

Phew!!! This makes a lot of sense, so I should remove the black plastic again. It seems to me that I read in Patricia Lanza's book (which I don't have right now) that she said she used black plastic in order to "cook" her lasagna beds, to speed up decomposition.

The link is very interesting for many reasons, but it does not really talk about applying plastic in the way I was doing it, over a basically raised bed, but rather as a mulch on the bare ground.

Any thoughts on how I can expedite my lasagna bed? Right now I am putting on coffee grounds (from three different Starbuck's and another coffee place), but this is the top layer, basically no layer at all, because it falls into the hay layer, which is above a horse manure layer, which is on top of semi decomposed leaves, which are on top of a little peat, which is on top of card board, which is on top of the dirt.

thank you Al and claypa.

Clementine, I'm sorry, I completely misunderstood. I thought you were preparing the ground for a future bed. Sorry! I'm sure some lasagna bed people will have better advice for you.

Thanks, claypa, at least you sent us that great website which has lots of good information. Yes, I hope someone else will have some ideas for me and hopefully you will see the progress of that discussion. In the meantime I have hurt my back, so everything will have to wait a while anyway. Old bones (or muscles)!

C.

You kill weed seed by generating heat in the compost. So the black plastic would be good. I have used heavy black plasic on my compost barrel to both generate and conserve heat. Takes about 160-175 degrees to kill seed.

Clementine,

Just an FYI- Itried that and developed a huge fireant ant bed. It was dry because the plastic blocked the rain and the ants loved the hot dry soil/mulch. I'm sure it will work if you water it but I just wanted to give you a heads up.

Maggie

Thank you all. Last night I read in P. Lanza's 'small gardening book and on p.20 she does say to use black plastic: "After you build the bed, cover it with black plastc and place bricks or stones around the edges (...) If outside temperatures are warm, a few weeks under the plastic should do the job. When you remove the plastic, most of the pile will be decomposed and ready for you to plant anything, even small seeds of seedling."

My question had really been about how you can best lay down the plastic so it does not get moved by wind where it overlaps. After some more thinking, I decided to just overlap the pieces more, like maybe 10" (I have a lot of the stuff, fortunately).

Margaran, this bed is quite wet, because we have had so much rain, so that would not invite fire ants. Actually, where I live we have found only one nest about 500 ft. from our house and we are going to treat it with the realy stuff (we bought it at Lowe's in Florida last November, Lowe's here does not carry it). On the east side of Chapel Hill we have seen lots of them.

Ozarkian, I don't have seeds (I am pretty sure) in my lasagna bed, my main purpose with the plastic is to speed up the decomposition process, so I can plant this spring.

The only way to "speed up composting" is to plan it when the weather is warm, to make the materials as small as possible, and to make the propper ratio of Nitrogen and Carbon. Shredding or mowing BEFORE you lay it down is what I do. If you want you could rototill the materials together this will chop up and speed up the process. Black stores up heat and keeps it longer. There fore I use black when I want to heat up anything. Note the Arabs in the desert are wearing black. This is because even though the desert is hot briefly it is cold most of the night.

I have a feeling that these beds won't come out right. I'll pull together all the info you all provided and see what happens, I will keep you posted. I have such wonderful seeds coming, I just hope I can plant some of them - red current tomatoes. for instance, that idea intrigued me so much I just had to get them.


Good luck to all of you.

I did some reading about lasagna beds, and one source said a main advantage of gardening this way is you can put the plants in right away. In your case, I think it depends how fresh the manure you're using is, though. This might interest you http://www.thriftyfun.com/tf582744.tip.html Good luck to you too!

Hi claypa: Yes, I have read that too, but the way it looks right now, I may have to check underneath first. I have cardboard on the bottom. We have had so much rain, I think it might be quite dissolved by now. I still am covering it with black plastic - just hoping. BTW, the link in the site you sent me does not work (www.lasagnagardening.com), in case someone was going to try looking at it.

Yesterday the funniest thing happened - to me anyway. I have been collecting coffee grounds, and my DH was always coming with me, somewhat reluctantly, thinking I was crazy. Yesterday, we had to go our separate ways and I came back with three bags of Starbuck's and he had been at two different ones and brought maybe 6 or 7 gallons worth of grounds. Isn't that wonderful? Now I have enough for all I wanted to cover. The next thing I need more of is carbonaceous stuff and horse manure. Such an adventure.