Skip to main content

Now is the Time to Prevent Summer Weeds!

So often, homeowners wait until weeds have overtaken their lawns in mid-summer before looking for a course of action to control them. Unfortunately, when weeds get to maturity and start producing flowers and going to seed, they are usually quite difficult to control.

[important]The best strategy is to prevent the weeds from getting established in the first place![/important]

Florida pusley

Florida pusley, an annual weed that can be controlled with preemergence herbicides. Photo credit: Mary Derrick UF/IFAS Extension.

When properly applied, a preemergence herbicide forms a chemical barrier on the surface of the soil that kills newly germinated seeds when they grow and contact that barrier. Be sure to follow label directions carefully as it is crucial to apply the correct amount and water it in correctly. The soil surface should not be disturbed after application to ensure that the chemical barrier remains intact.

Keep in mind that preemergence herbicides only prevent annual weeds! They do not control weeds that have already emerged.

In North Florida, the time to apply a preemergence herbicide to your turfgrass is coming soon. As a general rule, March 1 is an ideal time. Another indicator that the time is right is when the daytime temperatures reach 65°F-70°F for 4 to 5 consecutive days as that sustained warmth will prompt weed seeds to germinate. Oftentimes, this is also when azaleas or dogwoods start blooming and that can clue you into when to apply the herbicide. For best results, follow up with a second application in 6 to 9 weeks to control those seeds germinating later in the season.

Always follow the label instructions precisely when applying any herbicide! Ensure that you apply the product at the correct rate, that it is suitable for your specific turfgrass and situation, and that it is watered in correctly. For any pesticide, the label is the law!

If your lawn has problems with winter weeds, make a note on your calendar to apply a preemergence herbicide about October 1 in North Florida or when nighttime temperatures drop to 55°F-60°F for several consecutive days.

For more information on weed control in lawns:

Weed Management Guide for Florida Lawns

For general information on lawn care in Florida:

UF/IFAS Gardening Solutions: Lawns


4 Comments on “Now is the Time to Prevent Summer Weeds!

  1. After you apply a preemergence herbicide, when should you apply a fertilizer for the lawn?

    • In North Florida, your lawn should be fertilized no sooner than mid-April. The lawn should be already actively growing and mowed at least once before fertilizing. Fertilizer applied too early can run off or leach down through our sandy soils before the grass has a chance to use it. Please see for more information on fertilizing your particular turfgrass.

      • Thanks for the response. So I should apply a preemergence herbicide now and then fertilize by mid April, correct?

        Do I need to wait a certain time after the herbicide to fertilize? A week?

        • It’s best to apply the preemergence herbicide now and then fertilize AFTER April 15. The turfgrass should be fully out of winter dormancy and growing before fertilizing. Also, I recommend a lawn fertilizer that is a 15-0-15 or 15-2-15. The nitrogen (first number) and potassium (third number) should be balanced for best results.