Lawn Care Schedule for O'Fallon, Missouri
Zone 6b winters rarely drop below 0°F, giving cool-season lawns a slightly longer recovery window than zone 6a and an extended fall treatment season into late September. Pre-emergent goes down in mid-March as soil temperatures climb toward 55°F.
Missouri's summer heat pushes cool-season grasses into semi-dormancy; maintaining a 4-inch mowing height and consistent irrigation through July is the key to preventing permanent lawn thinning.
Zone 6b Timing Guide
- Pre-emergent window:
- mid to late March
- Active growing season:
- mid-March – mid-November
Local Pests & Diseases
Grub damage affects cool-season lawns statewide, while chinch bugs increasingly threaten Zoysia lawns in the southern part of the state.
Recommended Grass Types for O'Fallon
Month-by-Month Treatment Calendar
Occasional mowing in mild winters
Apply in warmer years as soil nears 50°F late in the month
Primary crabgrass preventer window
Light spring feeding for tall fescue
Continued spring feeding for cool-season grass
Treat emerged broadleaf weeds
Begin warm-season fertilization after green-up
Raise mowing height to 4 inches to reduce summer heat stress on fescue
Aerate warm-season grass during peak growth
Preventative grub control before eggs hatch
Aerate cool-season areas in late August
Overseed after aeration
Primary fall feeding for tall fescue
Winterizer application; warm-season grass enters dormancy
Final mow for the season
Related Guides
Treatment Guides for the Transition Belt
Fertilization
Feed your lawn at the right time — not on the bag's schedule.
Pre-Emergent
Stop crabgrass before it starts — timing is everything.
Post-Emergent
Kill the weeds that are already there — selectively and safely.
Overseeding
Thicken thin turf and fill bare spots during the optimal seeding window.
Aeration
Break up compaction and open the soil to water, air, and nutrients.
Watering
Water deep and infrequent — not shallow and daily.
Mowing
The one-third rule changes everything about how your lawn looks.
Grub Control
Prevent root damage before you see it — curative treatments are less effective.
Fungicide
Prevent disease before it spreads — fungicide rarely rescues an infected lawn.
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