The Ultimate Late Summer Weed Control Guide (Before They Spread in Fall)

By late summer, your lawn has already faced drought, heat, and heavy use — and now, weeds are gearing up for one last push before winter. If left unchecked, common Ontario weeds like dandelions, crabgrass, and clover will spread, steal nutrients, and return even stronger in spring.

The good news? Late summer is your last, best chance to stop them. In this guide, we’ll explain how to identify common lawn weeds, why timing matters, and the most effective strategies for weed control before fall.

🌱 Why Weed Control Matters in Late Summer

• 🌡️ Weeds are storing energy in their roots right now, preparing for fall and winter.
• ❄️ Uncontrolled weeds overwinter, returning thicker and harder to fight next spring.
• 🧪 Treatments are most effective in late August–September, when weeds actively pull nutrients (and herbicides) into their roots.
• 💸 Weed infestations = thinner turf, which means more costly overseeding and fertilization next year.

👉 Bottom line: Late summer weed control saves you work, time, and money.

🔍 Common Ontario Lawn Weeds in Late Summer

1. Dandelions
• Recognizable yellow flowers and fluffy seed heads.
• Fall control is crucial — each plant produces up to 15,000 seeds.
2. Crabgrass
• Spreads quickly in hot, dry weather.
• Dies in fall but leaves behind thousands of seeds for spring.
3. White Clover
• Low-growing with small white flowers.
• Fixes nitrogen into soil, often taking over thin lawns.
4. Plantain & Chickweed
• Broadleaf weeds that thrive in compacted soil and shady spots.
5. Creeping Charlie (Ground Ivy)
• Aggressive spreader in moist, shaded areas.

✅ Best Weed Control Strategies for Late Summer

1. Spot Treatments for Dandelions & Broadleaf Weeds

• Use selective herbicides or natural vinegar-based solutions.
• Apply when temperatures are cooler (morning or evening).
• Hand-pull stubborn weeds, ensuring the entire root is removed.

2. Pre-Emergent Control for Crabgrass (Next Season)

• Crabgrass can’t be stopped once mature — but applying pre-emergent herbicide in spring prevents seed germination.
• Aeration and overseeding this fall helps crowd out crabgrass seedlings next year.

3. Thicken Your Lawn with Overseeding

• Weeds thrive in thin lawns.
• Overseeding in late August–September gives grass the upper hand.
• Learn more: Overseeding 101: How to Repair Summer Lawn Damage Before Fall

4. Fall Fertilization Boost

• Feeding your lawn strengthens grass before winter.
• A thick, healthy turf in spring naturally chokes out weeds.

🧰 Pro Tip: Pair Weed Control with Aeration

Aerating your lawn before overseeding or fertilizing ensures nutrients (and treatments) reach the soil and roots. This also reduces compaction, making it harder for weeds like plantain or chickweed to thrive.

🏡 Professional Weed Control Services in Ontario

At Contract Link, we help homeowners across Kitchener, Waterloo, Guelph, Cambridge, Hamilton, Brantford, and beyond tackle weeds before they spread.

✔️ Late-summer and fall weed control programs
✔️ Eco-friendly and targeted treatments
✔️ Aeration, overseeding, and fertilization packages
✔️ Full seasonal lawn health assessments

👉 Book Your Weed Control Service Today

Don’t let weeds take over this fall — stop them now and enjoy a thicker, healthier lawn next spring. 🌱🍂