When to plant in St. Peters, MO
USDA Zone 6bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for St. Peters, Missouri — all computed from St. Peters's nearest NOAA weather station.
Zone 6b means St. Peters sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
ST PETERS 2 SE · 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 St. Peters’s own odds, recorded at ST PETERS 2 SE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 8 | Apr 23 | Apr 7 | Oct 4 | Oct 17 | Oct 27 |
| 32°F | Apr 25 | Apr 9 | Mar 27 | Oct 14 | Oct 26 | Nov 7 |
| 28°F | Apr 14 | Mar 31 | Mar 12 | Oct 25 | Nov 5 | Nov 22 |
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 St. Peters, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 11 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.
St. Peters planting FAQ
When is the last spring frost in St. Peters, MO?
On average, the last spring frost in St. Peters is around April 9 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in St. Peters, MO?
The first fall frost in St. Peters typically arrives around October 26 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is St. Peters in?
St. Peters 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 St. Peters?
There are roughly 200 frost-free days in St. Peters (a moderate growing season), running from the average last frost around April 9 to the first fall frost near October 26.
When should I plant tomatoes in St. Peters?
In St. Peters, start tomato seeds indoors around February 12–February 26, then transplant seedlings outdoors around April 16 once the danger of frost has passed.
Never miss a window in St. Peters
An email when it’s time to start seeds, transplant, and sow — timed to St. Peters’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- St. Charles · 8 km
- O'Fallon · 10 km
- Dardenne Prairie · 11 km
- Maryland Heights · 14 km
- Chesterfield · 14 km
- Lake St. Louis · 16 km
- Bridgeton · 16 km
- Hazelwood · 18 km
Frost dates recorded at ST PETERS 2 SE, 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 St. Peters, MO — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00237475. Retrieved from https://blissgarden.com/missouri/st-peters.