Answer: While it's true that covering existing lawn with black plastic will kill the lawn, black plastic is impervious to air and moisture, which can damage the soil and any roots from desireable plants that are under the plastic. Instead of black plastic, cover the area with weed barrier. This product has tiny holes in it to allow air and water to trickle down into the soil but it will effectively block light and the grass will die. The general guideline for tree and shrub roots is that they extend about one and one-half times the diameter of the canopy (dripline). Best wishes with your project!
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