How long after weed killer can i seed my lawn

Nothing designates spring’s arrival like walking barefoot on a lawn of lush, green grass. This pleasant experience can often turn into a painful, sticky… Are you trying to win a never-ending battle with weeds? Read this great information explaining how lawn weed control works, when the weeds will die if you use weed control, and if the weeds will come back.

Lawn Burweed

Nothing designates spring’s arrival like walking barefoot on a lawn of lush, green grass. This pleasant experience can often turn into a painful, sticky situation with the presence of lawn burweed. Other names for this weed are spurweed and stickerweed. Lawn burweed (Soliva sessilis) is a winter annual that germinates throughout thin turf in the fall months as temperatures cool. It remains small and inconspicuous during the cold winter months. However, as temperatures warm in the early spring, lawn burweed initiates a period of rapid growth and begins to form spine-tipped burs in the leaf axils. The seed is contained within the hooked bur.


Lawn burweed is a low-growing, freely branched winter annual. It has opposite, sparsely hairy leaves that are twice divided into narrow segments or lobes.

Leaves are approximately ½- to 1½-inches long and ¼- to ½-inch wide. It has small (¼ inch or less in width), inconspicuous flowers in the spring. It attains an overall diameter of 6 inches and a height of 3 to 4 inches. The most prominent identifying characteristic of lawn burweed is its spine-tipped burs, often hard to see but easily felt.

Lawn burweed (Soliva sessilis) growth habit.
Joseph M. DiTomaso, University of California – Davis,

Lawn burweed (Soliva sessilis) leaves and fruiting head.
Joseph M. DiTomaso, University of California – Davis,

Cultural Control

Maintain a healthy, dense lawn by fertilizing and liming according to soil test results and mowing at the proper height and frequency for the specific turfgrass in the lawn. Healthy lawn grasses can outcompete burweed for light, water, and nutrients and reduce the level of infestation. For more information on growing healthy turfgrass, see HGIC 1201, Fertilizing Lawns; HGIC 1205, Mowing Lawns; and HGIC 1207, Watering Lawns.

Chemical Control

Post-emergence Control: The key factor to effectively controlling lawn burweed is to apply a post-emergence herbicide during the winter months of December, January, and February. The weed is smaller and easier to control during this time of year and has not yet developed the spine-tipped burs. Control is not impossible in March, April, and May, but the spines have already formed by this time and will remain after the weed dies. Because lawn burweed is a winter annual, it will begin to die in late spring as air temperatures reach 90 °F. Once the weed has reached a more mature state, multiple herbicide applications may be necessary, which increases the potential for turfgrass injury. Dead or alive, lawn burweed poses a painful problem. The only solution to this is early identification and control.

Table 1. Turf Tolerance to Post-emergence Herbicides for Lawn Burweed Control.

Herbicide Bermudagrass Centipedegrass St. Augustinegrass Tall Fescue Zoysiagrass
atrazine D S S NR NR
(3- way) 2,4-D + MCPP + dicamba S I I S S
metsulfuron S S S-I NR S
iodosulfuron, & dicamba 1
S S S 2 NR S
S=Safe at labeled rates
I= Intermediate safety, use at reduced rates
NR= Not registered for use on and or damages this turfgrass
D=Fully dormant turf only. However, during the warmer winter weather of recent years, bermudagrass lawns have not gone fully dormant in South Carolina.
Note: Do not apply post-emergence herbicides, except Celsius WG Herbicide, to lawns during the spring green-up of turfgrass.
1 This mix of active ingredients requires the addition of 2 teaspoons of a non-ionic surfactant (that is, a wetter-sticker agent to aid in weed control, and added at 0.25% by volume) per gallon of water, such as Hi-Yield Spreader Sticker, Southern Ag Surfactant for Herbicides, or Bonide Turbo Spreader Sticker.
2 Spot treatments to St. Augustinegrass at temperatures above 90 °F may cause temporary growth regulation.

A three-way herbicide may be used on bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass, and tall fescue. The active ingredients of a three-way herbicide typically include the following three broadleaf weed killers: 2,4-D, dicamba, and mecoprop (MCPP). Products that contain a higher percentage of dicamba and mecoprop will more effectively control lawn burweed. 2,4-D controls this weed less well.

Herbicides containing 2,4-D should be applied at a reduced rate on St. Augustinegrass and centipedegrass to prevent damage to these lawns. If a second application is needed, apply the herbicide in spot treatments. Repeated applications of a three-way herbicide should be spaced according to label directions. Read the label for the rate to use on each turfgrass species. See Table 2 for examples of brands and products for use on residential lawns.

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In addition to three-way herbicides, there are several other herbicides that can be used for lawn burweed control in home lawns. Atrazine may be used for weed control in centipedegrass and St. Augustinegrass. Atrazine applied in November will have post-emergence activity against newly sprouted lawn burweed seedlings and also will have pre-emergence activity against those that have not yet germinated during the fall. Do not apply atrazine to lawns in areas with a high water table. Do not apply atrazine herbicides within two times the width of the drip line of desirable hardwood trees and shrubs. See Table 2 for examples of brands and products for use on residential lawns.

The herbicide mix of thiencarbazone, iodosulfuron, and dicamba, as found in Celsius WG Herbicide, is selective to control many broadleaf weeds and several grass weeds in all four of the common warm-season grasses. It cannot be used in fescue lawns but can be used to remove fescue from warm-season lawns. Apply when lawn burweed is actively growing and again 2 to 4 weeks later. Adding a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides or Hi-Yield Spreader Sticker Non-Ionic Surfactant, will increase control. Celsius WG Herbicide is safe to apply during spring green-up of warm season grasses.

Metsulfuron, such as in Quali-Pro MSM Turf Herbicide, gives very good control of lawn burweed in bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass lawns. Quali-Pro Fahrenheit Herbicide also contains metsulfuron along with dicamba. For these two professional products, a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides, Hi-Yield Spreader Stickers non-ionic surfactant, or Bonide Turbo Spreader Sticker, is required at 2 teaspoons per gallon of spray mix for best control. A non-ionic surfactant will help the herbicide adhere to the leaves for increased penetration.

Do not apply metsulfuron to lawn if over-seeded with annual ryegrass or over-seed for 8 weeks after application. Metsulfuron may cause temporary yellowing of turfgrass. Do not apply metsulfuron to turfgrass under heat and drought stress. Do not plant woody ornamentals in treated areas for one year after the application of metsulfuron. Do not apply metsulfuron herbicides within two times the width of the drip line of desirable hardwood trees and shrubs. Do not apply metsulfuron herbicides when high temperatures are above 85 °F.

CAUTION: Most post-emergence herbicides should not be applied during spring transition (green-up of lawn) or when air temperatures exceed 90 ºF as this may cause severe damage to the turfgrass. A newly seeded lawn should be mowed a minimum of three times before applying an herbicide.

Note: Read and follow all label instructions when using herbicides. Repeat applications 10 to 14 days apart may be required for acceptable control by post-emergence herbicides. Do not mow within 48 hours after the application of most herbicides. Most post-emergence herbicides need to dry on the leaf surface before irrigation or rainfall occurs.

Pre-emergence Control: Isoxaben is a pre-emergence herbicide for control of lawn burweed, as well as many winter broadleaf weeds in bermudagrass, centipedegrass, St. Augustinegrass, zoysiagrass, and tall fescue. Apply isoxaben in late September to early October before the winter weeds germinate. A repeat application may be needed 8 weeks later if there is a heavy infestation of weeds. Do not reseed or overseed within 60 days of last application, and do not apply to newly seeded lawns until the lawn has been mowed three times. Granular pre-emergence herbicides must be activated by ½ inch of rainfall or irrigation as soon as possible after application. See Table 2 for examples of brands and products for use on residential lawns.

Table 2. Herbicides to Control Lawn Burweed in Residential Turfgrass.

If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.

Original Author(s)

Morgan E. Judy, Former Extension Agent, Orangeburg County Extension Office, Clemson University

Revisions by:

Joey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University

This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.

How Does Lawn Weed Control Work, When Will Weeds Die, and Will They Come Back? (and More Answers)

Do you feel as though you’re fighting a never-ending battle with weeds? It can be so frustrating to feel like no matter what you do, the weeds just keep coming back. Weeds are not only an eyesore, detracting from the overall look of your lawn, but when they start taking over they begin to crowd out your healthy grass. Unfortunately, if not controlled, weeds can spread rapidly.

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If you’ve experienced this feeling, you aren’t alone. The truth is, there are many aggressive weeds in the Memphis, TN and Olive Branch, MS area and it can be difficult to get a handle on them without professional help.

Of course, if you’re considering a professional weed control program, you might have some questions. You may be looking to understand how it all works and whether it’s something you can do on your own or if you truly need to hire a pro.

In order to answer your questions and help guide you on the path toward a healthier lawn, we’ve rounded up some of the most common questions and our explanations all in one place.

How Does Weed Control Work?

If you’re thinking about using weed control, you might be looking to understand how it works. Weed control products work by interfering with weed growth either by blocking photosynthesis and protein production or by destroying or inhibiting root formation. Weed control products may be post-emergent or pre-emergent and are applied at different times for different purposes.

Pre-emergents are applied to the soil before weeds even emerge. These products create a barrier that prevents germination from even happening in the first place. The timing of pre-emergent products is critical to their effectiveness.

Since there is always a little bit of breakthrough (or perhaps the pre-emergent window was missed completely), there are also post-emergent products. These products are applied to the leafy areas of the weeds that are actively growing.

How Do I Kill Weeds in my Lawn Without Killing the Grass?

Another common question that we receive is how do I kill weeds in my lawn? More specifically, homeowners are often curious about how weeds in the lawn can be addressed without harming the grass.

The answer comes down to understanding the two main categories of weed control products: selective herbicides and nonselective herbicides.

Whereas nonselective herbicides are designed to kill all vegetation it’s applied to, there are selective herbicide products that are only designed to kill certain weeds.

Within these two main categories, there are a number of different products. It’s important to recognize that different weeds will require different treatments. Certain weeds, like nutsedge, might require specialty products. This is why a one-size-fits-all approach to weed control is not going to be effective. You want to find a company that will offer a customized weed control program that is specifically designed to target weeds on your property.

How Long Does it Take for Weeds to Die?

Weeds are more quickly controlled when growing conditions are great. If the weather gets really hot, very cold, or extremely dry, weed control results will be slowed down more than typical.

Generally speaking, we tell customers that if they don’t see weeds starting to yellow and die within 2 weeks to give us a call so that we can come back and make sure they’re taken care of. We think it’s important to stay on top of weed control for our clients as we know how much they value this service so we always ask to be “kept in the loop” if they feel something isn’t right.

Transforming a weedy lawn can take a good amount of time, specifically if the grass is thin and if you have some tougher varieties of weeds. We often tell new clients that although you’ll see great progress along the way, it can take 3-4 visits until there are drastic changes and to be patient. A year down the line, you’ll forget how your thick, lush lawn ever looked that bad!

How Long Does Weed Killer Work?

While certain weeds are easy to control and can be knocked back with just one treatment, other weeds are a bit more persistent and may require multiple treatments. While we wish we could say that once we treat weeds, they’ll never return, that’s simply not the case.

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Some of the more aggressive weeds, particularly grassy weeds (like crabgrass and dallisgrass) do continue to return and require ongoing treatment. Fortunately, when you’re on a comprehensive lawn care program, the goal is to stay ahead of these weeds and to use pre-emergent as effectively as possible. Then, we only have to spot-treat the breakthrough that pops up with post-emergent, selective materials.

Can I Implement Weed Control on my Own?

Now that you understand how these products work and what you can expect out of them, you might be wondering whether you can just implement a DIY program. After all, there are weed control products sold at the big box stores.

While there’s certainly nothing stopping you from handling weed control on your own, you’re not going to get as good results as you would with a professional program for several key reasons.

  • Product effectiveness: The weed control products sold at the store to homeowners are simply not as good as the professional-grade products used by a licensed technician.
  • Being able to mix products properly: Many times your professional lawn care technician will mix products together in order to give you the best possible combination. Homeowners likely don’t know which products to mix nor would they want to be dealing with mixing product (or storing product for that matter) at their home. There are also some additives that professionals will use at times for better results. For instance, Master Lawn adds surfactants, which is a wetting agent that helps materials not to bead up and roll off of leaf blades. This enhances results for some weeds.
  • Knowing when to treat: Lawn care technicians are highly trained to know exactly when to treat weeds—and that makes a big difference. Everything from wind speed to temperature can impact effectiveness. If a certain day isn’t ideal to treat, your lawn care technician can hold off. However, if you’ve only reserved the weekends for lawn care, you might have to apply product even when the conditions are not ideal. Since certain materials work better during certain times of the year, a professional will also switch up products when it’s warranted for better control.
  • Knowing how to treat: Again, technicians are going to be highly skilled in how to handle product. For instance, at Master Lawn we use different spray tips for different applications because the droplet size really does matter in terms of effectiveness. Similarly, a trained technician is going to know which products to use on which weeds. As we mentioned, it often takes a customized approach.
  • Implementing a full program: Finally, another key reason why a professional lawn care company is going to have better results than you would on your own is that they make weed control just one part of a complete program. Other lawn care services—like fertilization, aeration and overseeding, or the use of probiotic nutritional materials—which are aimed at thickening your lawn will also help it begin to naturally choke out weeds. The goal with a complete program is to get your lawn to a point where we do not have to spray as much product to get the same results because your thick and thriving lawn is naturally keeping weeds at bay.

Choosing a Lawn Weed Service in Memphis, TN or Northern Mississippi

In addition to avoiding a DIY approach to weed control, you also have to be selective about which company you choose to work with. Even amongst professional companies there are ineffective approaches to weed control. Unfortunately, some companies take a one-size-fits-all approach that isn’t going to provide you with the best possible control.

Your wise choice of lawn care companies in Memphis, TN or Olive Branch, MS will make a big difference in your battle against stubborn weeds. By selecting a lawn care company that will take a customized approach to your lawn, while also focusing on improving its overall health, you’ll be able to get better control over your lawn and start seeing the results that you desire.

If a lush green lawn is important to you, then you shouldn’t feel as though you’re stuck in a never-ending battle with weeds. By allowing an experienced professional to handle your weed control, you can take back your lawn and finally start enjoying it to the fullest.

Do you want weed control that really works? Talk to a lawn care expert, choose from 3 program options, and become the master of your lawn.