Fort Collins, CO Lawn Care Calendar
In a typical year, put down crabgrass preventer in Fort Collins between Apr 21 and May 19. The best time to overseed is between Jul 29 and Sep 17. The last spring frost usually comes around Apr 25. Most lawns here are cool-season grass (tall fescue, Kentucky bluegrass, ryegrass).
Typical lawn care dates in Fort Collins
| Task | Typical window |
|---|---|
| Crabgrass preventer (pre-emergent)Crabgrass sprouts once soil stays above 55°F. Apply when soil reaches 50°F, before that happens. | Apr 21 – May 19 |
| Spring fertilizerA light feeding once soil warms past 55°F and the grass is actively growing. | May 12 – Jun 16 |
| Overseeding & seedingLate summer to early fall: seedlings need about 6–10 weeks of growth before the first frost. | Jul 29 – Sep 17 |
| Fall fertilizerThe most important feeding for cool-season grass, from early fall until soil cools to about 45°F. | Aug 29 – Oct 30 |
Median dates, 2016–2025, from NOAA weather data for Fort Collins. This year's dates can differ by a few weeks.
Month-by-month lawn care in Fort Collins
- JanuaryNo treatments due; mow as needed.
- FebruaryNo treatments due; mow as needed.
- MarchNo treatments due; mow as needed.
- AprilCrabgrass preventer (pre-emergent)
- MayCrabgrass preventer (pre-emergent)Spring fertilizer
- JuneSpring fertilizer
- JulyOverseeding & seeding
- AugustOverseeding & seedingFall fertilizer
- SeptemberOverseeding & seedingFall fertilizer
- OctoberFall fertilizer
- NovemberNo treatments due; mow as needed.
- DecemberNo treatments due; mow as needed.
Soil temperature in Fort Collins by month
Average soil temperature 4 inches down, estimated from 2016–2025 weather. It bottoms out in January at 28°F and peaks in July at 73°F. Crabgrass preventer goes down when it reaches 50°F, usually around Apr 21.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28°F | 30°F | 39°F | 46°F | 55°F | 67°F | 73°F | 71°F | 65°F | 51°F | 40°F | 33°F |
Fort Collins lawn timing, year by year
Over the last 10 years, soil in Fort Collins reached 50°F, the signal for crabgrass preventer, as early as Mar 19 (2017) and as late as May 6 (2016): 48 days apart. A fixed calendar date can't follow that, which is why the report above uses this year's soil temperature. Between the typical last spring frost (Apr 25) and first fall frost (Oct 12), the growing season lasts about 170 days.
| Year | Crabgrass window opened | Last spring frost | First fall frost |
|---|---|---|---|
| 2025 | Mar 26 | Apr 21 | Oct 19 |
| 2024 | Apr 14 | Apr 22 | Oct 25 |
| 2023 | Apr 30 | Apr 24 | Oct 14 |
| 2022 | Apr 21 | Apr 27 | Oct 17 |
| 2021 | Apr 4 | Apr 23 | Oct 14 |
| 2020 | Apr 26 | Apr 19 | Sep 9 |
| 2019 | Apr 21 | May 21 | Oct 7 |
| 2018 | Apr 29 | Apr 26 | Oct 10 |
| 2017 | Mar 19 | May 20 | Oct 3 |
| 2016 | May 6 | May 3 | Oct 5 |
Estimated from daily temperatures for Fort Collins. A dash means it didn't happen that year.
Frequently asked questions
When should I apply pre-emergent in Fort Collins?
In a typical year, between Apr 21 and May 19. Put it down when soil reaches 50°F, before it stays above 55°F and crabgrass starts sprouting. Early springs move this up by a week or more, so check this year's soil temperature above.
When is the best time to plant grass seed in Fort Collins?
Early fall, typically Jul 29 – Sep 17, while soil cools from 65°F toward 50°F.
When is the last frost in Fort Collins?
The median last spring frost is Apr 25 and the median first fall frost is Oct 12 (2016–2025).
How long is the growing season in Fort Collins?
About 170 days, from the median last spring frost on Apr 25 to the median first fall frost on Oct 12 (2016–2025).
Lawn care guides
More Colorado lawn calendars
Nearby cities in other states
- Cheyenne, WY 40 miles away · crabgrass preventer May 12 – Jun 8
- Laramie, WY 56 miles away · crabgrass preventer May 20 – Jun 11
- Casper, WY 170 miles away · crabgrass preventer May 12 – May 29
- North Platte, NE 228 miles away · crabgrass preventer Apr 24 – May 14