Saint Peters, MO planting zone & frost dates
Saint Peters is in USDA hardiness zone 6b. The last spring frost usually comes around April 9 and the first fall frost around October 26, for a growing season of about 198 days.
Planting calendar for Saint Peters
Dates are counted from the average last spring frost (April 9) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 12 – Feb 26 Transplant outdoors: Apr 16 – Apr 23 |
| Peppers | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Apr 23 – Apr 30 |
| Eggplant | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Apr 23 – Apr 30 |
| Broccoli | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Mar 12 – Mar 26 |
| Cabbage | Start seeds indoors: Jan 29 – Feb 12 Transplant outdoors: Mar 12 – Mar 26 |
| Onions (sets) | Plant outdoors: Mar 12 – Mar 26 |
| Peas | Sow outdoors: Feb 26 – Mar 12 |
| Spinach | Sow outdoors: Feb 26 – Mar 12 |
| Lettuce | Sow outdoors: Mar 12 – Mar 26 |
| Carrots | Sow outdoors: Mar 12 – Mar 26 |
| Potatoes | Plant outdoors: Mar 12 – Mar 26 |
| Beans | Sow outdoors: Apr 16 – Apr 23 |
| Sweet corn | Sow outdoors: Apr 16 – Apr 23 |
| Cucumbers | Sow outdoors: Apr 16 – Apr 23 |
| Squash & zucchini | Sow outdoors: Apr 16 – Apr 23 |
| Basil | Start seeds indoors: Feb 26 – Mar 12 Transplant outdoors: Apr 16 – Apr 23 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 31 (8 weeks before the average first fall frost on Oct 26).
Useful for zone 6b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 27 | Apr 9 | Apr 25 |
| First 32°F frost in fall is before | Nov 7 | Oct 26 | Oct 14 |
How to read it: in spring there is a 10% chance of a frost after April 25, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 14. A hard freeze (28°F) usually ends around March 31.
Hardiness zone by ZIP code in Saint Peters
- 63376 zone 6b
Nearby cities
- O'Fallon zone 6b, last frost Apr 9
- Dardenne Prairie zone 6b, last frost Apr 10
- Chesterfield zone 7a, last frost Apr 4
- Saint Charles zone 7a, last frost Apr 8
- Lake Saint Louis zone 6b, last frost Apr 10
- Maryland Heights zone 7a, last frost Apr 2
- Bridgeton zone 6b, last frost Apr 2
- Ballwin zone 7a, last frost Apr 4
Questions
What growing zone is Saint Peters, MO?
Saint Peters is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map.
When is the last frost in Saint Peters?
The average last spring frost (32°F) in Saint Peters is April 9. There is still a 10% chance of frost until April 25.
When can I plant tomatoes in Saint Peters?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 16 – Apr 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station St Peters 2 Se, MO (USC00237475), 4.8 km (3.0 mi) from the city center, elevation 175 m, based on 14 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.