When To Apply Pre Emergent In Texas - JC's Landscaping

hen to apply pre-emergent in Texas? Many lawn and garden experts agree that you should apply a pre emergent herbicide in late winter/early Spring and also in late fall.  Texas weather is usually warmer in February than most other states in the US.

The key factor to watch is soil temperature, not the calendar. For pre-emergents to be effective, apply them just before soil temps hit 55°F, when weed seeds begin to germinate. This ensures the herbicide creates a barrier that stops weeds before they sprout.

Why Soil Temperature Matters

Applying pre-emergents too early—when the soil is too cold—reduces the herbicide’s effectiveness. Applying too late—after germination—means the weeds are already growing. Use a soil thermometer or check online soil temperature maps for your region.

Why Use Pre- and Post-Emergent Herbicides?

Even with proper fertilization, mowing, irrigation, and aeration, unexpected weather patterns in Texas—like heavy rains or drought—can cause lawns to thin out and become vulnerable to weeds.

That’s where pre- and post-emergent weed control comes in:

• Pre-emergent herbicides stop weeds before they break through the soil.

• Post-emergent herbicides kill weeds that are already growing.

Together, these products act like an insurance policy for your yard.

Pro Tip: Always follow product labels for application instructions and mowing restrictions. Mowing too soon before or after applying herbicides can reduce their effectiveness.

Understanding the Difference Between Pre and Post Emergent

Pre-emergent herbicides create a chemical barrier in the soil, targeting weed seeds before they germinate. Use them for common Texas weeds like crabgrass, goosegrass, and spurge start growing.

Post emergent herbicides killactively growing weeds. There are two main types:

• Selective post-emergents target weeds without harming your lawn.

• Non-selective post-emergents kill all vegetation—including turfgrass—on contact.

In Texas, you can typically begin using post-emergents as early as April, once weeds begin to emerge and temperatures stay between 65°F–85°F.

Are Pre- and Post-Emergents Safe for Kids and Pets?

Yes—with caution. Most herbicide labels indicate they are safe for children and pets once fully absorbed into the soil. However, direct contact before absorption can be harmful.

Safety tips:

• Granules can stick to a dog’s fur and absorb through the skin.

• Liquid herbicides may be ingested if children or pets touch or sniff treated grass.

• Exposure before absorption may cause vomiting, rashes, diarrhea, or respiratory issues.

Wait at least 24–48 hours after application before allowing pets or children on treated areas. For maximum safety, 72 hours is ideal.

Temperature, Weather & Timing for Maximum Effectiveness

Timing is everything when it comes to herbicide success.

• Apply pre-emergents when soil reaches around 55°F.

• Apply post-emergents when air temperatures range between 65°F–85°F.

Avoid applying during:

• Cold spells – products won’t activate properly.

• Heat waves – herbicides may evaporate before working.

• Heavy rainstorms – can wash away or dilute the product.

Always check the forecast before applying any treatment.

Suggested Herbicides for Texas Lawns

✅ Best Pre-Emergent Herbicide

• ProdiamineLongest-lasting and highly cost-effective due to low application rates.

✅ Best Post-Emergent Herbicides

• Celsius HerbicideGreat for warm-season grasses like St. Augustine, Bermuda, Centipede, and Zoysia.

• Speedzone Southern BroadleafExcellent broadleaf weed control; safe for most turfgrasses.

Final Thoughts: When to Apply Pre-Emergent in Texas

To recap:

• Apply pre-emergents when soil temps hit 55°F—usually in late winter/early spring and again in late fall.

• Pair with post-emergents during the growing season for complete coverage.

• Always read product labels and follow usage instructions.

• Keep pets and children off treated lawns for 24–72 hours.

With proper timing and care, you’ll be well on your way to maintaining a weed-free, vibrant Texas lawn all year long.

D Boone