When to plant in Port Huron, MI
USDA Zone 6bPort Huron, Michigan frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Zone 6b means Port Huron sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
The average first fall frost in Port Huron is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
PORT HURON · 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 Port Huron’s own odds, recorded at PORT HURON.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 18 | May 1 | Apr 18 | Oct 6 | Oct 22 | Nov 4 |
| 32°F | May 4 | Apr 19 | Apr 7 | Oct 20 | Nov 3 | Nov 16 |
| 28°F | Apr 21 | Apr 7 | Mar 25 | Nov 1 | Nov 12 | Nov 28 |
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 Port Huron, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 32 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.
Port Huron planting FAQ
When is the last spring frost in Port Huron, MI?
Port Huron's average last spring frost falls near April 19 — 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 Port Huron, MI?
Expect Port Huron's first fall frost near November 3 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Port Huron in?
Port Huron is in USDA hardiness zone 6b. In zone 6b, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Port Huron?
There are roughly 198 frost-free days in Port Huron (a moderate growing season), running from the average last frost around April 19 to the first fall frost near November 3.
When should I plant tomatoes in Port Huron?
In Port Huron, start tomato seeds indoors around February 22–March 8, then transplant seedlings outdoors around April 26 once the danger of frost has passed.
Never miss a window in Port Huron
An email when it’s time to start seeds, transplant, and sow — timed to Port Huron’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- New Baltimore · 42 km
- Mount Clemens · 57 km
- Rochester · 66 km
- Fraser · 66 km
- Sterling Heights · 67 km
- St. Clair Shores · 67 km
- Roseville · 68 km
- Rochester Hills · 70 km
Frost dates recorded at PORT HURON, 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 Port Huron, MI — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00206680. Retrieved from https://blissgarden.com/michigan/port-huron.