How to Control Weeds in Your Lawn

The first time my lawn erupted into a sea of purple violets, I actually rather liked it – I tend to evaluate a plant’s beauty first before sealing its doom by calling it a “weed.” For the most part, however, gardeners prefer for their turf grass and their flowers to stay in their respective places and for weeds to stay out of the picture altogether.

Weed Prevention

While fighting weeds is a year-round job, weed prevention is best practiced in the fall and early spring to take advantage of the growing season of turf grasses. A healthy, thick lawn is your number one defense against weeds. In fact, a badly weed-infested lawn is usually a sign of nutrient imbalance or other soil problems.

For a nice, green lawn that is free of weeds, focus first on getting your grass healthy, then give it a couple of months to become strong before applying weed control products. Minimize turf areas, so that you’re only growing grass where grass easily grows. A small patch of healthy grass is far more attractive than a huge expanse of thin, weedy lawn.

                      Clover, while good for the soil, is a frequent lawn-invader.

If you’re amending your soil or sowing new grass seed, buy high-quality seed and consider mixing your own soil amendments using only the best ingredients. Pre-mixed topsoil from landscape supply yards often contains weed seeds.

Weed Control

Small patches of weeds can be handled by pulling or digging. All-over lawn weed control is usually not necessary either, as a heavy infestation would be better handled by making the grass healthy. However, for those in-between situations, you may want to consider the use of a chemical or organic herbicide.

          Smartweed (polygonum sp.) can take over poorly-drained, moist areas

To choose the correct herbicide, it’s helpful to understand some basic terms that appear on the labels of commercially-packaged weed control products.

  • Pre-Emergent herbicides work by preventing seed germination, so they don’t do much good after the weeds are growing. They’re best used as a preventative spot-treatment in known weedy patches, during the winter or summer dormant season.
  • Post-Emergent herbicides work by killing growing plants, usually by interrupting chemical processes such as photosynthesis, protein production, or root growth. They are best applied when the plant is actively growing and in the fall when plants are storing up nutrients in their roots. This allows the herbicide to be quickly sucked down into the roots where it is most effective. Post-emergent herbicides can work on contact (killing only the vegetation they touch) or systemic (absorbing into and killing the entire plant).
  • Selective herbicides target only certain types of plants by identifying specific enzymes or other plant chemicals. Frequently you’ll see selective herbicides designed to target monocots (such as grasses or other strappy-leaved plants) or dicots (all other plants, often referred to as “broadleaf” plants).
  • Nonselective herbicides kill any plant they contact and should be used for spot-treatment only.
  • Total vegetation herbicides kill all plants and sterilize the ground for a certain period of time – they should be used very carefully.

So how do these terms work together when shopping for herbicide? Here are some common examples:

  • Glyphosphate (found in products such as Roundup) is a post-emergent, nonselective, systemic herbicide. That means it kills any actively growing plants that it contacts. It’s good for spot-treatment but should be used carefully on windy days, especially around roses.
  • “Weed & Feed” products (such as Sta-Green Winterizer Weed & Feed) usually contain 2,4-D or other post-emergent, selective herbicides. They’re designed to selectively kill broadleaf weeds without harming grass. However, weed & feed products can kill St. Augustine grass, so check the label to see if it’s safe for this type of lawn before using.
  • Trifluralin (contained in products such as Preen Garden Weed Preventer), on the other hand, is a pre-emergent, nonselective herbicide that will kill grass seeds as well as weed seeds and is only for use in established gardens.

  • Corn Gluten (found in products such as Concern Weed Prevention Plus) is a natural substance produced by corn that prevents surrounding weeds from growing. It is packaged as an organic pre-emergent herbicide that selectively targets broadleaf weeds.
  • Grass killers (such as Ortho Grass-B-Gon) are post-emergent, selective weed killers that target grasses. They are used in flower beds to kill weed grasses.
  • Combination Herbicides (such as Ortho Ground Clear) contain more than one post-emergent, nonselective herbicides (such as glyphosphate and imazapyr). Imazapyr is very slow to break down, so this product is designed to kill every plant it contacts and to keep the ground sterile for up to one year.

As with any chemical product, follow package instructions carefully, and only use if absolutely necessary. Herbicides can affect surrounding plants and can pollute ground water when used improperly or in large quantities. By carefully selecting the correct product, you can get rid of those pesky weeds in no time.

              My purchased potting-soil often includes “bonus” morning glories.

Further Information

For more on dealing with weeds in your lawn:

For help identifying garden weeds:

For detailed information about specific weeds and control methods:


  1. From the different weed killers you have in the picture of the spray bottles, I would have to recommend Round-Up as the most effective spray.

  2. But what if I like clover? I think it’s pleasant, withstands some traffic, grows well in the shade, and plays well with other shady grasses if mowed.

    Is there such a thing as a Weed control product that doesn’t kill clover? I’ve heard that clover was considered part of a healthy lawn until ads for Weed ‘n Feed came out and then clover was villianised.

  3. Otis, I rather like clover too. But most lawn weed control products target “broadleaf” weeds, which includes clover (and many garden flowers as well). To get rid of other weeds and keep the clover, you’ll have to spray or pull those weeds individually. And you’re right – clover seeds used to be a standard ingredient in lawn grass seed. For more information, check out A Yard Full Of Clover.

  4. So what do you use on a weed that isn’t a broadleaf but thin & spindly that shoots its hundreds of seeds out when it dies off??? If pre emergent kills the grass also

  5. Concerned as my distributor has gone from Talstar to an expensive add Arena chemical to regular spray because they think it is better. I was not even having trouble with chinch bugs. I have been deciding whether to start using my own yard care as I use to for years instead of others coming in. Have taken out one area of yard to be planted with Floratam as the Winter months in Fl were extremely hard on one section. We are in midst of replanting. Now the Arena spray has been destroyed and need to redo all the control of the new grass ourselves. I need your thoughts on Talstar and Arena, which do you recommend? And I need your advice on fertilizing as the weather is now reaching 90 and above and we have to be careful.

  6. I stopping having weed control service because it was driving birds away – probably killing them. Is there any weed control that does not injure birds?

  7. We planted spreading junipers on a steep bank about 8 years ago. Area about 50′ by 50′- they have spread and covered the bank 100%. Last 2-3 years a spreading, spindly type of grass has invaded. We pulled up the grass last year and this year it is back – worse than last year. Stems have a purple cast to them. We’ve pulled it all again this year, but as we pull, we can hear the seeds dropping. It is now the last week in October. What do you suggest to keep this invasion away next year? We cannot pull the grasses any earlier in the year – too many bees & mosquitoes hide in the junipers.

  8. Susie,

    Correct me if I’m wrong…but if you get rid of all the golfers, they’re gonna lock you up and throw away the key!

  9. When I looked through my 5/4/2011 list on ” How to control weeds in your lawn” there was a site to go to for additional information on “How to control Bermuda Grass” This link is no longer available. How can I find this information again?

  10. We have hybrid bermuda grass. We spayed early with 24,D. None of the weeds have died. The product was purchased last year (with same results) and has been kept from freezing. What product should we spray to rid our lawn of ALL wild grasses? We have a 2-acre lawn. We need HELP fast.

  11. Question regarding outdoors —How do I get rid of the underground moles that are destroying my front yard landscaping. Anything I plant they eat the roots and then die. H E L P !!!!

  12. I have a 2 acre lawn of Hybrid Bermuda grass. My husband took very good care of our lawn before suffering a stroke in 2009. I have inherited this job. I don’t know the difference in crab grass or broadleaf weeds. Our lawn has not been maintained in 3 years so it’s really overgrown in “stuff.” I need to know what as far as a brand or name of a herbicide to take care of all the stuff and when to apply and whether to us liquid or granular. Thanks!

  13. Concur w/your comment that “Pre-mixed topsoil from landscape supply often contain weed seeds”! Developed an amazing crop of Black-medic second year after applying a pre-mixed nutrient mix of ‘regional compost’ + local sewage treatment plant material. Hand weeded for three years but cannot get ahead of it! Where do you recommend I access a top soil that does NOT contain weed seed?

  14. My yard is full of all kinds of different weeds. If I spray Round-up over the whole yard say mid February while it is cold and the Bermuda is dormant. Will that kill the weeds only, or will the grass be killed also?

  15. I have used Ortho be Gone on very small clover in patches in my hyrid bermuda, but it doesn’t seem to kill very much of it. I used to have a lawn that people said I could putt on it. Alas, I need a weed killer to kill all weeds except my hybrid bermuda. Got any suggestions?

  16. When should a weed PREVENTATIVE be put on a lawn?? Wait until for Forsythia bloom? By that time a lot of weeds are all over the lawn. Or do it BEFORE the weeds take control? Zone 7 Thank you.

  17. Sorry, but if you have a weed infested lawn then your focus should be two part, with weed control being the first. The focus on getting a well developed thick lawn is very important no doubt, but to get there you must remove or eliminate whats competing against your laws in the first palace. You can address the PH of your soil, lightly fertilize in the spring and over seed in the fall to thicken your grass but if your lawn is in competition with killer weeds then your throwing money away each year and getting no where! While a thick healthy lawn is key to keeping weeds at a minimum You’ll never get there if your first priority thick healthy grass only. When you establish beautiful growing environment for lawn you also establish that environment for weeds and weeds will grow out of control like crabgrass, clover, and other invasive plants. So if your going to lightly fertilize in the spring make sure you address weeds before germination and defiantly before they really get growing strong.

  18. So i have a Major weed problem due to neglect since winter. my front yard and spots in my back yard have begome infested with dandelions to the point where my yard is nearly 50% weeds and pulling them 1 at a time would take days. not to mention the weeds would be growing behind me while im battling the weeds. i tried using weed killer on the weeds but it only slightly slowed the tide of weeds encrouching on my yard. any tips to deal with large amounts of weeds?

  19. what is a safe herbicide that I can use to kill purple violets in lawn that will not harm wildlife or pets? Too many to pull by hand…

  20. Hi Danny,
    I my backyard there are few patches of White Clover, and I want to kill them. I tried to pull them, but they spread now to 2″x3″ area. Is there any chemical herbicides I may use? What’s the best season for killing them?


  21. I was at the Clark County fair in Vancouver Wash. I talked to an expert on the weeds I have. He told me to use sedgehammer. I have tried several different stores. No one has that product. Where can I get it?


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