Adding underlayments between the rocks and the soil creates a weed barrier that helps prevent weed seeds from touching the soil. If you already have rocks in place, rake them away temporarily while you install the underlayments. Choose landscape fabric or black plastic as the underlayments.
A post-emergent herbicide kills weeds as soon as they sprout. Choose a non-selective herbicide such as one containing glysophate so it will kill nearly any kind of weed that appears. Care is essential when spraying the non-selective herbicide near your bushes because it can harm or kill bushes as well as weeds. Protect the bushes from herbicide drift by placing plastic or a large piece of cardboard between the bushes and where you spray, and spray only on days that aren’t windy.
Best Weed Barrier Under Rocks
Rocks, including river rocks and gravel, commonly serve as mulch to help keep weeds from finding a home in flowerbeds. When you cover a rock garden completely in rocks, you have built-in mulch support. Whether your garden has large boulders as part of its design or is low and flat, using color and texture for design, ensure the area is covered completely with small rocks serving as mulch. Scrape the rock mulch about 2 inches away from the trunks of the bushes to help prevent root rot and other fungal infections.
Because water passes through the landscape fabric under your rocks, holes in it need to be only large enough to fit around the bushes’ trunks. Cut lines in the fabric from its sides nearest to the holes for the trunks, so you can wrap the fabric around them. Covering the fabric with rocks helps hold it in place, although placing landscape staples every 2 feet or so along each edge of the fabric also helps.
The Chemical Herbicide Option
Plastic is the best weed barrier under rock, but water won’t pass through it to feed the bushes’ roots. An option is to use the plastic, but leave large holes in it around the bushes. Alternatively you can combine the underlayments, placing landscaping fabric around the bushes and then covering the rest of the rock garden with heavy plastic. You’ll still leave holes for the bushes, but that space will be weed resistant because of the landscaping fabric.
This article was co-authored by Lauren Kurtz and by wikiHow staff writer, Hunter Rising. Lauren Kurtz is a Naturalist and Horticultural Specialist. Lauren has worked for Aurora, Colorado managing the Water-Wise Garden at Aurora Municipal Center for the Water Conservation Department. She earned a BA in Environmental and Sustainability Studies from Western Michigan University in 2014.
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Even through rock mulch and gravel, weeds will somehow find a way to grow. Luckily for you, these can be handled like weeds in any other part of your garden. You can spray a chemical killer, pull them by hand, or use a variety of household materials to help keep your yard free of these plant pests.
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