When to plant in Owosso, MI
USDA Zone 6aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Owosso, Michigan — all computed from Owosso's nearest NOAA weather station.
In zone 6a, Owosso gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in Owosso is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
OWOSSO 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 Owosso’s own odds, recorded at OWOSSO WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 28 | May 11 | Apr 28 | Sep 22 | Oct 4 | Oct 16 |
| 32°F | May 17 | May 1 | Apr 17 | Oct 1 | Oct 15 | Oct 30 |
| 28°F | May 5 | Apr 20 | Apr 5 | Oct 12 | Oct 28 | Nov 11 |
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 Owosso, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 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.
Owosso planting FAQ
When is the last spring frost in Owosso, MI?
Owosso's average last spring frost falls near May 1 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Owosso, MI?
In Owosso, the first 32°F freeze of fall lands around October 15 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Owosso in?
Owosso 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 Owosso?
Owosso has about 167 frost-free days — a moderate growing season — between the average last spring frost (May 1) and first fall frost (October 15).
When should I plant tomatoes in Owosso?
For Owosso, sow tomatoes indoors about March 6–March 20 and move the seedlings out around May 8, after the last spring frost.
Never miss a window in Owosso
An email when it’s time to start seeds, transplant, and sow — timed to Owosso’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at OWOSSO 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 Owosso, MI — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00206300. Retrieved from https://blissgarden.com/michigan/owosso.