How to Control Fall Weeds in Your Lawn

Why Fall Weed Control Works Better

Fall is actually the most effective time to control perennial lawn weeds. As temperatures cool, weeds shift energy from leaves to roots. Herbicides absorbed by the foliage travel down to the root system, killing the entire plant rather than just the top growth.

Common Fall Lawn Weeds to Target

Broadleaf Weeds

Dandelions, clover, plantain, and chickweed are most vulnerable in autumn. Their deep taproots are actively storing energy, making systemic herbicides highly effective.

Grassy Weeds

Crabgrass dies naturally with the first frost, but nutsedge and annual bluegrass (poa annua) persist through fall and winter. Pre-emergent herbicides applied in early fall prevent poa annua germination.

Best Herbicide Strategies for Fall

Spot Treatment

For isolated weed patches, use a ready-to-spray herbicide containing 2,4-D, dicamba, and mecoprop (MCPP). Spray directly on weed leaves on a calm, dry day when temperatures are above 60 degrees F.

Broad Application

If weeds cover more than 25% of your lawn, consider a broadcast application of a three-way herbicide. Mix according to label directions and apply with a pump sprayer for even coverage.

Non-Chemical Fall Weed Control

• Hand pulling after rain: Wet soil makes it easier to remove the entire root system
• Thick lawn density: A thick lawn crowds out weeds naturally. Overseed thin areas.
• Proper mowing height: Keep grass at 3 inches to shade weed seedlings
• Corn gluten meal: A natural pre-emergent that also adds nitrogen

Fall Weed Control Timeline

• Early September: Apply pre-emergent for poa annua prevention
• Mid-September to October: Spot treat broadleaf weeds when actively growing
• November: Final spot treatment before dormancy, remove visible weed crowns

Consistent fall weed control reduces your spring weed burden by 60-80%. The key is targeting weeds while they are still actively transporting nutrients to their roots.