The Best Time to Spray Weed Killer Revealed

February 13, 2024
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Free your Oklahoma City lawn from stubborn weeds. Say goodbye to endless weeding and welcome the lush, green space you deserve.

You’ve pulled and sprayed, but those pesky invaders keep popping up like unwelcome guests at a barbecue. At Don’s Lawn Care in OKC, we understand the unique challenges of Oklahoma City’s climate and soil. This blog will focus on the best time to spray weed killers and address related concerns.

The Importance of Timing in Weed Control

When it comes to effective weed control, timing is everything. The best time to spray weed killer is a critical factor that can significantly impact the success of your lawn care efforts. Applying herbicides at the right moment ensures maximum efficacy and minimizes potential harm to desirable plants.

Crafting a Weed-Killing Schedule

To optimize the effectiveness of weed killer, consider the following factors when planning your lawn care routine:

  • Seasonal Considerations: Different seasons bring varying challenges for weed control. For optimal results with herbicide-based weed killers, it’s advisable to avoid using them in hot weather, as their effectiveness tends to decrease. Instead, target weeds during the more favorable seasons of Spring or Fall. 
  • Temperature Matters: Weed killer efficacy is closely tied to temperature. The warmer months generally provide an ideal environment for herbicides to work effectively. Aim for a temperature range that allows the weed killer to be absorbed and translocated within the plant. Extreme heat (above 90°F) or cold (below 50°F) can stress plants and reduce the effectiveness of herbicides. 
  • Time of Day: Spraying weed killer at the right time of day significantly impacts its effectiveness. Early morning or late afternoon are often the best times, offering optimal conditions for absorption and avoiding the harsh midday sun.

When Is the Best Time to Spray Weed Killer?

Understanding the optimal timing for weed killer application involves considering a range of factors.


The spring’s warm soil awakens weed seeds from their slumber. This presents an opportunity for pre-emergent weed killers, which prevent seeds from germinating in the first place. 

  • Target: Crabgrass, dandelions, and other annual weeds.
  • Timing: Early spring, just before the soil temperature consistently reaches 50°F. In Oklahoma City, this typically falls between late February and early March.
  • Benefits: Stops weeds before they sprout, saving you time and effort.


Fall is the season for post-emergent weed killers. By this time, weeds have matured, actively drawing nutrients from the soil. Fall weed killers disrupt this process, starving the weeds and depleting their energy reserves before winter.

  • Target: Established broadleaf weeds, like dandelions, clover, and pesky grasses.
  • Timing: For best results, apply during early to mid-fall when temperatures are mild, ideally between 60°F and 70°F, and before the first frost hits. In Oklahoma City, this typically means targeting late September to mid-October.
  • Benefits: Applying pre-emergent during this period makes weeds more vulnerable to winter conditions, leading to a higher die-off rate. This approach simplifies weed control come spring.


Even with the best pre-emptive measures, some persistent weeds might sneak through. Summer is the time for selective post-emergent weed killers, which target specific weeds without harming your desired lawn.

  • Target: Individual weeds that have escaped pre-emergent or fall treatments.
  • Timing: Any day with calm winds, temperatures below 85°F, and no rain forecast for at least 24 hours. Oklahoma City’s mild summers offer ample windows throughout the season.
  • Benefits: Eliminates individual weeds without harming your lawn.

To enhance weed-killing success, ensure calm winds during herbicide application, as strong winds above 5 mph can carry herbicide droplets to unintended areas, posing a risk to desirable plants and nearby water sources.

Best Time to Spray Weeds Before or After Rain

Before Rain: Applying weed killer just before rainfall can enhance its effectiveness. Rain helps distribute the herbicide evenly across the target area, ensuring better coverage.

After Rain: While post-rain application is feasible, waiting for the soil to dry slightly is essential. Applying weed killer to waterlogged soil may dilute its potency and reduce its impact on weeds.

When Is the Best Time to Spray Roundup?

Roundup works best when applied during the active growth phase of weeds. This often coincides with the warmer months, making late spring and early summer optimal for Roundup application.

When Is the Best Time to Spray Pastures for Weeds?

Pasture management requires careful consideration, as certain weeds can threaten livestock. The best time to spray pastures for weeds is typically during the growing season, when weeds actively take in nutrients.

Best Time to Use Weed-Killer on Lawn

For general lawn maintenance, the best time to use weed-killer on your lawn is during the early stages of weed growth, during spring. Applying during the spring prevents weeds from establishing deep roots and becoming more challenging to eradicate. 

Best Time to Put Down Weed and Feed

When considering the best time to put down weeds and feed, aligning with your lawn’s growth cycles is essential. Generally, these products yield the best results when applied in spring or fall, corresponding with when your grass is in its active growth phase.

Don’t wait until your lawn becomes a weed battlefield!

Launch your preemptive strike with Don’s Lawn Care OKC. We’re the experts in weed control in OKC, and we’ll help you achieve a flourishing green lawn. Contact Don’s Lawn Care OKC today for a free consultation, and let us show you the power of spring-time weed control!


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