Use of black plastic to kill grasses and prepare beds?

organic_gardenmomApril 12, 2007

I have a large area that I would like to make into a children's garden next Spring (2008.) Its a mixture of weeds, wildflowers and mostly bermuda grass right now. I'm thinking about putting down black plastic and leaving it there for a while in attempt to kill off the existing bermuda. Can anyone tell me if this will be effective and if so, will it be very damaging to the soil? How long would I need to leave the plastic there for this to be effective?

We currently have a 400 sq. ft organic garden and we are just dealing with the bermuda by constantly digging it up or cutting it down. I'd love to have a bit a fresh start on this new project! ;) I realize that the bermuda runners can creep back in, but I'm hoping to get a head start on them!

Thanks in advance for any advice!

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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

You can of course but I find that multiple layers of newspaper and cardboard works better. You might also want to consider the lasagna gardening approach to this spot. Here is a link to many discussions on its advantages.

Here is a link that might be useful: Lasagna Garden Building

    Bookmark   April 12, 2007 at 12:08PM
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gardenlen(s/e qld aust)

g'day organic gardenmom,

our solution is documented on our gardening site, check under 'building a garden' or 'strawbale garden' lots of pic's the kids can look at and easy to read dialogue.


Here is a link that might be useful: len's garden page

    Bookmark   April 12, 2007 at 3:07PM
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terran(zone10/Sunset20 CA)

I do not have any particular experience with lasagna gardening applied to the eradication of Bermuda grass, but am in the process of trying to rid the roadside of that invasive. It is my belief that Bermuda would grow through the lasagna substrate.

If I remember correctly, clear plastic does a better job of solarization than the black.

In the case of Bermuda, I expect that solarization is the way to go. I expect that in its native habitat it does its job very well, but it should never have been allowed out of that confinement.

Heating the soil will undoubtedly destroy soil organisms, but the soil will recover.


    Bookmark   April 12, 2007 at 3:39PM
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Dibbit(z7b SC)

Clear plastic does a better solarizing job than the black, if the area is in full sun - the plants cook in the heat. Use thick enough plastic that a dog running over it won't tear it, as that will defeat the purpose. As well, be sure that it won't flap in any breeze and tear.

It will kill any Bermuda grass directly under it, but any growing out the sides will survive. BG is one of the things I expect to survive a nuclear blast! Lasgna gardening MAY, if thick enough, kill it off, but more probably will only encourage it.

Earth worms and largish organisms will move out of the heat, some will encyst themselves, and all the microherd will recolonize when the plastic is removed. Spreading a little compost around will speed the process up.

    Bookmark   April 12, 2007 at 4:47PM
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Because Bermuda grass spreads by rhizomes, stolens, and seed you may well be better off removing the sod before trying to make a new planting bed there. Covering the area may well kill off the top growth but it is unlikely to get hot enough, deep enough to kill the rhizomes which will simply grow back as grass later. Many people have written that covering Bermuda grass will not be enough to kill it off. You should also plan on putting some kind of barrier around this bed to keep the roots from reinvading in the future.

    Bookmark   April 12, 2007 at 5:17PM
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Dibbit(z7b SC)

In my experience with wire grass (aka BG), the rhizomes can go down 6-15 inches, so removing the sod (2-6") won't get rid of them. The BG you are dealing with may be different.

Removing the sod will get rid of the topmost layer of green grass, and also many of the seeds, but.... IF the soil is loose (which it should be after lasagna layers have broken down), and IF you keep on top of it, it is relatively easy to keep pulling the BG out, getting as much of the roots as you can each time. If you do keep on top of it, you can discourage it to the level of a minor problem, and maybe, after enough years, get rid of it in that one area.

    Bookmark   April 12, 2007 at 9:28PM
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Thanks so much for all the responses! I love the hay bale garden! We live in South Texas, so I think I have the heat going for me. I'm still not sure how deep it will kill the bermuda rhizomes, but I do know its going to get HOT! :)

I'm so glad I found this forum!


    Bookmark   April 12, 2007 at 11:14PM
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dchall_san_antonio(8 San Antonio)

WAIT WAIT WAIT!!! It's a STRAW bale garden, not a HAY bale garden. Big difference. Straw will not have any seed in it. With hay, you get the seed that grew the hay. It could be crabgrass, which makes a pretty good forage.

Also black plastic has a different use than clear plastic. Clear plastic is used to solarize, or heat up the soil underneath. Black plastic is used to shade out bermuda so it will die. I am not sure what the temp gets to under the black plastic, but the idea with black is not to raise the temp, but to provide dark shade. I should work to kill the bermuda. I am killing mine right now with an inch or so of sand.

    Bookmark   April 13, 2007 at 3:20PM
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gardenlen(s/e qld aust)

you can use straw or hay, whatever is convenient.

what i actually used was mostly bales of pasture grass hay and bales of sugar can mulch, straw quiet often contain seed from the left over harvest, harvesters do not harvest 100% so you can get growths but these are not weeds and nothing to worry about, i have used straw and experienced that, but where it is possible to get grass growing from hay it is not any more probable, our instances of sprouting from hay are negligable.

any sproutings we do get we pull up when they are large enough and tuck them under the mulch as extra nutrient, they have never become a perpetuating weed. we spend almost nill time weeding.

the grass we had to cover was kykuya (spelling?) it is a very hard grass to control in the same league as nut grass, so we feel confident that if anyone uses the same processes we did they will get just as good results. once a grass is destroyed it does not matter how strong the runners or seeds are they will not survive the composting effect under the process we use.


Here is a link that might be useful: len's garden page

    Bookmark   April 13, 2007 at 3:52PM
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gardnpondr(Zone 8)

on the Lasagna gardening method......... if you live in the south like I do, you might not want to put that close up around your house. A friend of ours got the idea from me and he did this around his trees he planted wayyyyyy back in the field behind his house. He kept noticing the ant hills around the beds so he removed some of the paper trying to get rid of the ants. Then he decided to remove the bottom layer of paper and under the paper was loads and loads of termites. He said it was crawling with them. Said they were eating the paper. So I am going to remove what I have up close to my house because I don't want to draw them to my house. I'm using this method on out away from the house but not against it anymore.
Just wanted to allert you to this.

    Bookmark   May 1, 2007 at 10:21PM
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I live in Salt Lake City and covered my front yard with black plastic the end of Mar. When I take it off I'll plant plugs of buffalo grass. If I have to, I can leave it on until next spring. I can't use Roundup because I have a 2 year old border of Ribes nigrum Crandall (black clove currant) and a large Catalpa with roots underneath the whole area.

    Bookmark   May 3, 2007 at 5:19AM
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Simnce this is an organic gardening forum and since any glyphosate product (Roundup and all the others) are not acceptable organic products they should not even be mentioned here.
gardnpondr, very often when you start to make your soil into something other than the dead, sterile soil that is the norm today you will see an increase in insect life. Because a large number of us do not understand what role insects play in the environment we often think any insect is bad and needs to be eliminated which is not true. What your friend most likely saw were ants working on that paper, not termites, but because he did not know what he was looking at made invalid assumptions. I have termites around here, the house is inspected every year because of that, but I have not seen any sign of termites in mulches in some 50 years. The 5 species of termites you have (I only have 2 species) may be slightly different but not that much.

    Bookmark   May 3, 2007 at 6:37AM
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I had snow on the mountain plants that mutated back to solid green, became a bit larger and spread like mad. I can't get rid of them even with Roundup. Any suggestions?

    Bookmark   May 17, 2011 at 3:07PM
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