Zone 3b Club · Lawn Calendar
Zone 3b Lawn Calendar
Year-round timing tuned to Zone 3b's climate window.
Winter low
-35°F
Last frost
May 20
First frost
Sep 20
Season
120d
Primary Overseeding Window
Aug 20 → Sep 15
The single highest-leverage window for cool-season seed in Zone 3b.
Quarter
Spring in Zone 3b
- ▪Late May: rake winter damage and overseed thin spots (KBG primary, PRG nurse)
- ▪First mow when grass reaches 4 inches; cut to 3 inches
- ▪Apply 0.5–0.75 lb N/1000 sqft around late May–early June
- ▪Pre-emergent crabgrass at soil temp 55°F (late May)
Quarter
Summer in Zone 3b
- ▪Mow at 3–3.5 inches
- ▪1" water per week including rain; deep + infrequent
- ▪Hold fertilizer in July–August on non-irrigated lawns
- ▪Brown patch is rare here — focus on watering discipline
Quarter
Fall in Zone 3b
- ▪Primary overseeding: Aug 20 – Sep 15 (soil temps 60–70°F)
- ▪Most important fert of the year: 1 lb N/1000 sqft in late August
- ▪Aerate compacted areas before overseed
- ▪Final mow at 2.5 inches by mid-October
Quarter
Winter in Zone 3b
- ▪Lawn dormant under snow
- ▪Avoid traffic on frozen turf — crown damage is permanent
- ▪Plan spring purchases in February
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