Thermopolis 9NE, WY Lawn Care Calendar

Every timing-sensitive lawn job in Thermopolis 9NE, timed to the local climate record — not a national average.

Turf region
Cool-season
Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue
Last spring frost
May 24
median, 1991–2020
First fall frost
Sep 16
median, 1991–2020
Growing stretch
115 days
frost to frost
TaskThermopolis 9NE windowWhy then
Crabgrass pre-emergent May 3 – May 24 Soil nearing 55°F — must beat germination
Light spring feeding May 24 – Jun 21 After green-up, before summer stress
Aerate + overseed Jul 18 – Aug 2 Fall growth surge; established before cold
Main fall feeding Jul 22 – Aug 19 The year’s most important nitrogen
Winterizer feeding Aug 19 – Sep 2 Root reserves for spring green-up
Final mow Sep 9 – Sep 30 Growth stops around first frost

Anchored to NOAA 1991–2020 climate normals at the THERMOPOLIS 9NE station. Windows are estimates — soil temperature is the real trigger, especially for pre-emergent. Check your own ZIP with the lawn calendar lookup.

Thermopolis 9NE lawn care, month by month

MonthTasks
January Dormant — keep leaves cleared, stay off frozen turf
February Dormant — keep leaves cleared, stay off frozen turf
March Dormant — keep leaves cleared, stay off frozen turf
April Dormant — keep leaves cleared, stay off frozen turf
May Apply crabgrass pre-emergent · Light feeding after green-up
June Light feeding after green-up
July Aerate + overseed · Main fall feeding
August Aerate + overseed · Main fall feeding · Winterizer feeding
September Winterizer feeding · Final mow of the year
October Dormant — keep leaves cleared, stay off frozen turf
November Dormant — keep leaves cleared, stay off frozen turf
December Dormant — keep leaves cleared, stay off frozen turf

Reading the Thermopolis 9NE lawn year

Thermopolis 9NE runs on the classic northern rhythm: a short, important spring (pre-emergent before soil hits 55°F, one light feeding), a defensive summer (mow tall, water deep, feed nothing), and then the season that actually builds a lawn — early fall, when aeration, overseeding around Jul 18 – Aug 2, and the year's main feeding all land before the Sep 16 frost closes the year. With only ~115 frost-free days, the fall window is tight — miss it and the next real chance is spring.

Grasses that fit Thermopolis 9NE

Frequently asked questions

When should I overseed my lawn in Thermopolis 9NE?

For cool-season grass (bluegrass, fescue, ryegrass), overseed in early fall — in Thermopolis 9NE that means roughly Jul 18 – Aug 2, timed 45–60 days before the average first fall frost (Sep 16) so seedlings establish before cold. Spring works as a backup but collides with crabgrass season.

When do I put down crabgrass preventer in Thermopolis 9NE?

Aim for May 3 – May 24 — the estimated stretch when Thermopolis 9NE soil approaches the ~55°F germination threshold, anchored to the average last frost (May 24). It's an estimate: a soil thermometer reading 50–55°F at 2″ depth for several days is the precise trigger, and pre-emergent must go down before crabgrass sprouts, not after.

When should I stop mowing in Thermopolis 9NE?

Keep mowing as long as the grass grows — in Thermopolis 9NE that's typically until Sep 9 – Sep 30, around the average first fall frost (Sep 16). Take the final cut slightly shorter to discourage snow mold.

What grass grows best in Thermopolis 9NE?

Wyoming is cool-season country: Kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue. See the grass guides linked below for identification and care.