Using plastic to kill crabgrass roots

I am turning an area where a tree stump was ground out into a flower bed. I've defined the edges but there are crabgrass roots all through it. Would think black plastic covering it for a few months kill the roots? If so, where does one purchase it?
  7 answers
  • Douglas Hunt Douglas Hunt on Jun 21, 2013
    You don't need plastic. Put several thicknesses of cardboard over the area, then a layer of mulch over that. Some people cut holes in the cardboard and plant immediately, but I would wait a few months and then work the decomposed cardboard and the mulch into the ground. You'll have a fine bed for flowers.

  • Sheila Lynn Sheila Lynn on Jun 26, 2013
    Thanks for that Douglas. I think we will try that instead of the plastic. Last time I was doing this I used old carpet and left it for quite a long time. Worked great but wasn't pretty. LOL

  • Sheila Lynn Sheila Lynn on Jun 26, 2013
    I do have another question tho - should we use wood chip mulch or grass clippings?

  • Douglas Hunt Douglas Hunt on Jun 27, 2013
    You can use either, or both, Sheila. You'll want to make sure the wood chips are fairly small so they break down more readily.

  • Sheila Lynn Sheila Lynn on Jun 28, 2013
    Ok. Thanks so much. Been running about getting LOTS of cardboard. LOL. Have lots of clippings that aren't compost yet too.

  • Sheila Lynn Sheila Lynn on Aug 06, 2013
    Hi again. So in JUly we covered the whole area with think newspaper and cardboard with mulch over the top. had a fantastic rain storm and now this is growning on the mulch. Is is a problem? I'm sure it's fungus but not sure if good or bad.

  • Sheila Lynn Sheila Lynn on Aug 06, 2013
    Picture didn't show up on the last post so... here is photo.

    • Douglas Hunt Douglas Hunt on Aug 07, 2013
      @Sheila Lynn That is slime mold, sometimes delightfully known as dog vomit fungus. It is harmless on top of mulch, but you can scoop it up and toss it into the garbage if it bothers you. Technically, it is between a bacterium and a fungus.