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Tips for a Thick, Weed-Free Lawn


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By Fabian Menalled, Ph.D., the Weed Science Society of America

I don’t know about you, but every year I struggle to keep weeds from taking over my lawn.  In fact, it seems the only weed-free turf I see is when watching golf on TV.

While herbicides can help, no single product will work against all the weeds found in lawns. For example, products that contain 2,4-D will control most broadleaf weeds, but won’t manage weedy grasses like crabgrass and foxtail.

So what’s a homeowner to do? The best solution is a dense and vigorous lawn that can block sunlight and capture the moisture and nutrients weeds need.  Here are a few tips to get you started on that thick, luxurious turf:

  • Fertilize appropriately.

A good fertilization program can help you grow a dense lawn.  But use the right amount.  Too much fertilizer wastes your hard-earned money and increases the chance of runoff.  Too little can lead to a sparser lawn, which gives clover and other weeds the space and sunlight needed to grow.  So strike the right balance.  Get a soil test and follow the recommendations, and consider using a slow-release product.

  • Mow high, as needed. 

Mowing can help you manage bothersome, broadleaf weeds.  But pick the right interval.  Mowing too frequently weakens your grass and exposes the soil surface so weed seeds can sprout and grow.  Mowing too seldom reduces the growth of side stems needed for a dense lawn. Most experts recommend that you mow your lawn to a height of 2 to 4 inches and that you mow frequently enough to keep it within that range.

  • Avoid overwatering. 

Usually lawns need only about one inch of water per week.  Don’t overwater, or you will promote disease.  When there isn’t sufficient rainfall, provide your lawn with infrequent soakings – watering deeply enough to promote deep-rooted grass.  Make certain to comply with any watering restrictions in your community, though.

  • Know your weeds and treat them appropriately. 

Most weeds found in lawns fall into two main groups: annuals and perennials. Annual weeds die at the end of each growing season and produce new plants from seeds only. They often are not that difficult to control. Mowing regularly is often all you need to prevent them from flowering and producing seed.  Weedy annuals that grow flat to the ground, though, can escape mowing and are best pulled by hand or controlled with herbicides.

A perennial plant produces seed, but can also grow back each year from underground roots, bulbs and rhizomes.  To control perennials, apply an appropriate herbicide or chop off the above-ground portion of the plant each time it regrows.  If you repeat the process faithfully, the plant may eventually die – though it can sometimes take years.  One thing you DON’T want to do is try to dig them up.  New weeds can grow from any pieces of the underground root system that break off, compounding your problem rather than correcting it.

If you are unable to determine whether your weeds are annuals or perennials, contact your extension office. Experts can help you identify your weed and design an effective management program that integrates proven best practices.

  • Know your herbicides and use them appropriately.

When using an herbicide to treat weeds, choose one labeled for your type of lawn and your type of weeds. Follow the directions carefully. Some herbicides work only at certain weed growth stages or at a specific time of year.  If used incorrectly, they can injure or kill your grass and other desirable plants.

If despite your best efforts you don’t get a lush, weed-free lawn, I recommend you follow my example and enjoy the outdoors anyway.  I’m learning to live with my dandelions!


This column is provided as a courtesy by the Weed Science Society of America (WSSA).  The author Fabian Menalled is a crop weed specialist in Land Resources and Environmental Sciences at Montana State University.

Download the high resolution images of yellow nutsedge and quackgrass.

Quackgrass image courtesy of Steve Dewey, Utah State University, Bugwood.org.
Yellow nutsedge image courtesy of Lynn Sosnoskie, University of Georgia, Bugwood.org.
Lawn image courtesy of William M. Brown Jr., Bugwood.org.

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