Boise, ID Lawn Care Calendar
In a typical year, put down crabgrass preventer in Boise between Apr 10 and May 8. The best time to overseed is between Aug 3 and Sep 22. The last spring frost usually comes around Apr 20. Most lawns here are cool-season grass (tall fescue, Kentucky bluegrass, ryegrass).
Typical lawn care dates in Boise
| 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 10 – May 8 |
| Spring fertilizerA light feeding once soil warms past 55°F and the grass is actively growing. | May 1 – Jun 5 |
| Overseeding & seedingLate summer to early fall: seedlings need about 6–10 weeks of growth before the first frost. | Aug 3 – Sep 22 |
| Fall fertilizerThe most important feeding for cool-season grass, from early fall until soil cools to about 45°F. | Sep 10 – Nov 2 |
Median dates, 2016–2025, from NOAA weather data for Boise. This year's dates can differ by a few weeks.
Month-by-month lawn care in Boise
- 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
- JulyNo treatments due; mow as needed.
- AugustOverseeding & seeding
- SeptemberOverseeding & seedingFall fertilizer
- OctoberFall fertilizer
- NovemberFall fertilizer
- DecemberNo treatments due; mow as needed.
Soil temperature in Boise by month
Average soil temperature 4 inches down, estimated from 2016–2025 weather. It bottoms out in January at 32°F and peaks in July at 75°F. Crabgrass preventer goes down when it reaches 50°F, usually around Apr 10.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 32°F | 36°F | 43°F | 49°F | 57°F | 66°F | 75°F | 74°F | 66°F | 53°F | 42°F | 33°F |
Boise lawn timing, year by year
Over the last 10 years, soil in Boise reached 50°F, the signal for crabgrass preventer, as early as Mar 15 (2017) and as late as Apr 29 (2021): 45 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 20) and first fall frost (Oct 17), the growing season lasts about 180 days.
| Year | Crabgrass window opened | Last spring frost | First fall frost |
|---|---|---|---|
| 2025 | Mar 25 | Apr 14 | Oct 28 |
| 2024 | Apr 13 | May 1 | Oct 19 |
| 2023 | Apr 28 | Apr 21 | Oct 28 |
| 2022 | Mar 26 | May 11 | Oct 24 |
| 2021 | Apr 29 | Apr 13 | Oct 13 |
| 2020 | Apr 21 | Apr 18 | Oct 22 |
| 2019 | Apr 5 | May 2 | Oct 1 |
| 2018 | Apr 21 | Apr 18 | Oct 14 |
| 2017 | Mar 15 | May 14 | Oct 9 |
| 2016 | Apr 3 | Apr 17 | Oct 12 |
Estimated from daily temperatures for Boise. A dash means it didn't happen that year.
Frequently asked questions
When should I apply pre-emergent in Boise?
In a typical year, between Apr 10 and May 8. 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 Boise?
Early fall, typically Aug 3 – Sep 22, while soil cools from 65°F toward 50°F.
When is the last frost in Boise?
The median last spring frost is Apr 20 and the median first fall frost is Oct 17 (2016–2025).
How long is the growing season in Boise?
About 180 days, from the median last spring frost on Apr 20 to the median first fall frost on Oct 17 (2016–2025).
Lawn care guides
More Idaho lawn calendars
Nearby cities in other states
- Elko, NV 194 miles away · crabgrass preventer May 2 – May 28
- Kennewick, WA 230 miles away · crabgrass preventer Mar 31 – May 3
- Missoula, MT 249 miles away · crabgrass preventer May 10 – May 27
- Bend, OR 257 miles away · crabgrass preventer May 7 – Jun 4