Zone 4a Club · Lawn Calendar
Zone 4a Lawn Calendar
Year-round timing tuned to Zone 4a's climate window.
Winter low
-30°F
Last frost
May 15
First frost
Sep 25
Season
130d
Primary Overseeding Window
Aug 25 → Sep 20
The single highest-leverage window for cool-season seed in Zone 4a.
Quarter
Spring in Zone 4a
- ▪Mid-May: overseed winter damage; KBG primary
- ▪First mow at 4 inches; maintain 3 inches
- ▪Apply 0.75 lb N/1000 sqft in late May
- ▪Pre-emergent crabgrass at soil temp 55°F
Quarter
Summer in Zone 4a
- ▪Mow at 3–3.5 inches
- ▪1" water per week; deep + infrequent
- ▪Skip July fert on non-irrigated lawns
- ▪Watch for summer patch on KBG-heavy lawns under stress
Quarter
Fall in Zone 4a
- ▪Primary overseeding window: Aug 25 – Sep 20
- ▪Apply 1 lb N/1000 sqft late August (the year's biggest fert)
- ▪Aerate and overseed compacted areas
- ▪Final mow at 2.5 inches by late October
Quarter
Winter in Zone 4a
- ▪Lawn dormant Nov–April
- ▪Avoid frozen turf traffic
- ▪Plan spring purchases in February
Continue at Premium Grass Seeds
Build the fall window before it opens.
Use the calendar for timing, then move through the three buying decisions in order. Start with the zone-filtered seed comparison, then use the matching starter and equipment guides. The seed comparison stays anchored to Zone 4a.
1 · Seed
Compare zone-fit fall seed
Start with overseeding options that list this zone, then confirm the local establishment window.
Open: Compare zone-fit fall seed → (opens in a new tab)2 · Starter
Pair the starter fertilizer
Pick the establishment feed after the seed; it is not a substitute for it.
Open: Pair the starter fertilizer → (opens in a new tab)3 · Equipment
Stage the overseeding tools
Choose the spreader, prep, and watering gear before the window opens.
Open: Stage the overseeding tools → (opens in a new tab)
Want this as a downloadable one-pager?