Spring Weeds Are Here: Understanding Soil Temperatures & Effective Weed Control

As the Midwest slowly transitions from winter to spring, weeds are waking up and beginning to germinate. This time of year, it’s common to see an increase in weed growth as soil temperatures steadily rise. Understanding when and how to treat weeds is key to keeping your lawn healthy and weed-free throughout the season.

Why Are Weeds So Common Right Now?

Soil temperatures are one of the biggest factors influencing weed germination. Right now, soil temps in the Midwest are hovering in the 45-55°F range, which is prime time for early spring weeds to sprout. Many of these weeds thrive in cool conditions and take advantage of weak areas in your lawn.

Common Weeds Germinating Now:

• Henbit – A common purple-flowered weed that thrives in cool soil.

• Chickweed – Spreads quickly in moist, shady areas.

• Annual Bluegrass (Poa Annua) – A sneaky, fine-textured weed that blends in with your lawn.

• Mustard Weeds – Characterized by their small yellow flowers, often popping up in early spring.
• Nimblewill – A warm-season perennial grass-like weed that becomes more noticeable as temperatures rise. It starts greening up in spring and spreads aggressively in thin or shaded areas.

If left untreated, these weeds can quickly take over, competing with your grass for nutrients and water. That’s why early intervention is critical to maintaining a strong, healthy lawn.

When is the Right Time to Spot Spray for Weeds?

Many homeowners make the mistake of spot spraying too early when the ground is still too cold. For post-emergent herbicides (weed killers) to work effectively, soil temperatures need to be consistently above 45°F.

Why is 45°F the Magic Number?

✔️ Weeds Need to be Actively Growing – Herbicides work by being absorbed into the weed’s system. If the soil is too cold, weed growth is sluggish, and the herbicide won’t be as effective.

✔️ Better Absorption = Better Control – A weed killer applied when soil temperatures are below 45°F may not be absorbed properly, leading to poor results and wasted effort.

✔️ Timing is Key – If you wait too long, weeds become tougher and more difficult to control. Early treatment (once temps are consistently warm enough) gives you the best chance at eliminating them before they mature and spread seeds.

 What Heartland will do

✅ Monitor Soil Temperatures – Make sure soil temperatures are consistently above 45°F before applying post-emergents.
✅ Apply Pre-Emergent Weed Control – This will prevent summer weeds like crabgrass from taking over your lawn.
✅ Fertilize & Strengthen Your Lawn – A thick, healthy lawn is your best defense against weed invasions.

What you can do

✅ Mow & Remove Early Growth – Keeping your lawn properly mowed can help prevent weeds from spreading seeds.

Final Thoughts: Timing is Everything

Spring weed control is all about understanding soil temperatures and taking action at the right time. Spot spraying too early won’t be effective, and waiting too long gives weeds a chance to spread. If you’re unsure about when or how to treat your lawn, let Heartland Turf help!