Last Updated on March 16, 2021

How Long After Spraying Weeds Can I Mow?

You may be wondering, is it better to spray weeds before or after mowing? Is there a window of time to treat weeds in your mowing schedule?

Learn how to make the most of your weed treatment!

Can I Apply Weed Killer Right After I Mow?

Weed killers, or post-emergent herbicides, need to be applied to the leaves of the weed in order to be effective. If the weeds are freshly mowed, there is less broadleaf weed surface area for the herbicide to stick to, and your lawn treatment will be less effective.

It’s best to wait at least two days after mowing before applying any weed killer. This will give the weeds time to grow and provide your herbicide more surface area to penetrate.

Can I Mow After I Treat My Yard for Weeds?

It’s best to wait at least two days after weed treatment before you cut grass. Otherwise, you may cut off the weed killer you just applied! Weed treatment, especially 24d, needs time to absorb into the leaves of the weeds.

When is The Best Time to Water After Using Weed Killer?

Don’t water immediately after applying post-emergent weed killer. Watering will wash the weed killer off the leaves of the weeds. Watch the weather. Try to apply weed killer when there isn’t any rain in the forecast. If an unexpected shower occurs, you may need to reapply the herbicide.

When is The Best Time to Apply Weed Killer?

Some weed killers, including Roundup and 24d, will not work as well in cold temperatures. Temperatures need to be at least 55 degrees when the weed killer is applied and for at least four hours afterward. Plan to apply these weed killers midday during a warm spell for the best results.

As always, check the label of your weed killer for instructions. Keep children and pets off the lawn for 24-72 hours after applying weed killer.

What About Pre-Emergent Herbicide?

Pre-emergent herbicides are designed to stop weed seeds from germination. This is applied in the fall or spring. Contact your local county extension office for timing advice. Typically, pre-emergent weed killers need to be applied when the soil is between 50-55 degrees.

It is necessary to water lawns immediately after the application of pre-emergent weed killer. Don’t mow until after the yard has been watered and the pre-emergent has soaked into the ground.

What is The Best Method to Apply Weed Killers?

Granular Weed Killer

A granular weed killer, such as Scotts Weed and Feed, can be applied with a fertilizer spreader. Always follow the package directions. Weed and feed claims to kill weeds and fertilize grass in one step.

To help the granules stick to the weeds’ leaves, it may help to lightly water the lawn before application.

Liquid Weed Killer

Some yard specialists prefer a liquid weed killer. It can be easier to spray directly onto weeds instead of a whole yard application. Liquid weed killer can be applied with a spray bottle, a hose attachment, or a backpack sprayer.

It is not necessary to water the lawn before using a liquid weed killer.

Final Thoughts

Pulling weeds is tough work! An herbicide will make a tough job much easier. Make sure to follow instructions for proper application. Don’t mow the yard too soon after treating weeds, and your weed killer should have plenty of time to work.


Author: Matt Hagens

Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.