Granite City, IL planting zone & frost dates
Granite City is in USDA hardiness zone 7a. The last spring frost usually comes around April 1 and the first fall frost around November 4, for a growing season of about 218 days.
Planting calendar for Granite City
Dates are counted from the average last spring frost (April 1) 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 4 – Feb 18 Transplant outdoors: Apr 8 – Apr 15 |
| Peppers | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Apr 15 – Apr 22 |
| Eggplant | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Apr 15 – Apr 22 |
| Broccoli | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Mar 4 – Mar 18 |
| Cabbage | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Mar 4 – Mar 18 |
| Onions (sets) | Plant outdoors: Mar 4 – Mar 18 |
| Peas | Sow outdoors: Feb 18 – Mar 4 |
| Spinach | Sow outdoors: Feb 18 – Mar 4 |
| Lettuce | Sow outdoors: Mar 4 – Mar 18 |
| Carrots | Sow outdoors: Mar 4 – Mar 18 |
| Potatoes | Plant outdoors: Mar 4 – Mar 18 |
| Beans | Sow outdoors: Apr 8 – Apr 15 |
| Sweet corn | Sow outdoors: Apr 8 – Apr 15 |
| Cucumbers | Sow outdoors: Apr 8 – Apr 15 |
| Squash & zucchini | Sow outdoors: Apr 8 – Apr 15 |
| Basil | Start seeds indoors: Feb 18 – Mar 4 Transplant outdoors: Apr 8 – Apr 15 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 9 (8 weeks before the average first fall frost on Nov 4).
Useful for zone 7a 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
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 14 | Apr 1 | Apr 18 |
| First 32°F frost in fall is before | Nov 21 | Nov 4 | Oct 24 |
How to read it: in spring there is a 10% chance of a frost after April 18, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 24. A hard freeze (28°F) usually ends around March 22.
Hardiness zone by ZIP code in Granite City
- 62040 zone 7a
Nearby cities
- East Saint Louis zone 7a, last frost Apr 8
- Cahokia zone 7a, last frost Apr 6
- Collinsville zone 7a, last frost Apr 8
- Wood River zone 7a, last frost Apr 4
- Glen Carbon zone 7a, last frost Apr 4
- Alton zone 7a, last frost Apr 4
- Fairview Heights zone 7a, last frost Apr 8
- Upper Alton zone 7a, last frost Apr 4
Questions
What growing zone is Granite City, IL?
Granite City is in USDA Plant Hardiness Zone 7a (average extreme winter low 0°F to 5°F), according to the USDA 2023 map.
When is the last frost in Granite City?
The average last spring frost (32°F) in Granite City is April 1. There is still a 10% chance of frost until April 18.
When can I plant tomatoes in Granite City?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 8 – Apr 15. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station St Louis Sci Ctr, MO (USC00237452), 13.2 km (8.2 mi) from the city center, elevation 157 m, based on 25 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.