When to plant in Howell, MI
USDA Zone 6aEverything below — frost dates, hardiness zone, and what to plant when in Howell, Michigan — is derived from the closest NOAA station with complete climate normals.
Zone 6a means Howell sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
HOWELL WWTP · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Howell’s own odds, recorded at HOWELL WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 31 | May 16 | Apr 30 | Sep 17 | Sep 29 | Oct 10 |
| 32°F | May 21 | May 4 | Apr 20 | Sep 27 | Oct 7 | Oct 21 |
| 28°F | May 11 | Apr 24 | Apr 11 | Oct 5 | Oct 20 | Nov 3 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Howell, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 21 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Howell planting FAQ
When is the last spring frost in Howell, MI?
Plan for the last spring frost in Howell around May 4 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Howell, MI?
Expect Howell's first fall frost near October 7 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Howell in?
Howell is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Howell?
There are roughly 156 frost-free days in Howell (a moderate growing season), running from the average last frost around May 4 to the first fall frost near October 7.
When should I plant tomatoes in Howell?
In Howell, start tomato seeds indoors around March 9–March 23, then transplant seedlings outdoors around May 11 once the danger of frost has passed.
Never miss a window in Howell
An email when it’s time to start seeds, transplant, and sow — timed to Howell’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at HOWELL WWTP, 2 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Howell, MI — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00203947. Retrieved from https://blissgarden.com/michigan/howell.