Chatham, IL planting zone & frost dates
Chatham is in USDA hardiness zone 6a. The last spring frost usually comes around April 15 and the first fall frost around October 22, for a growing season of about 188 days.
Planting calendar for Chatham
Dates are counted from the average last spring frost (April 15) 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 18 – Mar 4 Transplant outdoors: Apr 22 – Apr 29 |
| Peppers | Start seeds indoors: Feb 4 – Feb 18 Transplant outdoors: Apr 29 – May 6 |
| Eggplant | Start seeds indoors: Feb 4 – Feb 18 Transplant outdoors: Apr 29 – May 6 |
| Broccoli | Start seeds indoors: Feb 4 – Feb 18 Transplant outdoors: Mar 18 – Apr 1 |
| Cabbage | Start seeds indoors: Feb 4 – Feb 18 Transplant outdoors: Mar 18 – Apr 1 |
| Onions (sets) | Plant outdoors: Mar 18 – Apr 1 |
| Peas | Sow outdoors: Mar 4 – Mar 18 |
| Spinach | Sow outdoors: Mar 4 – Mar 18 |
| Lettuce | Sow outdoors: Mar 18 – Apr 1 |
| Carrots | Sow outdoors: Mar 18 – Apr 1 |
| Potatoes | Plant outdoors: Mar 18 – Apr 1 |
| Beans | Sow outdoors: Apr 22 – Apr 29 |
| Sweet corn | Sow outdoors: Apr 22 – Apr 29 |
| Cucumbers | Sow outdoors: Apr 22 – Apr 29 |
| Squash & zucchini | Sow outdoors: Apr 22 – Apr 29 |
| Basil | Start seeds indoors: Mar 4 – Mar 18 Transplant outdoors: Apr 22 – Apr 29 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 27 (8 weeks before the average first fall frost on Oct 22).
Useful for zone 6a 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 | Apr 3 | Apr 15 | Apr 30 |
| First 32°F frost in fall is before | Nov 2 | Oct 22 | Oct 9 |
How to read it: in spring there is a 10% chance of a frost after April 30, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 9. A hard freeze (28°F) usually ends around April 5.
Hardiness zone by ZIP code in Chatham
- 62629 zone 6a
Nearby cities
- Springfield zone 6a, last frost Apr 15
- Taylorville zone 6a, last frost Apr 12
- Jacksonville zone 6a, last frost Apr 17
- Lincoln zone 6a, last frost Apr 20
- Decatur zone 6a, last frost Apr 14
- Godfrey zone 7a, last frost Apr 4
- Upper Alton zone 7a, last frost Apr 4
- Pekin zone 6a, last frost Apr 16
Questions
What growing zone is Chatham, IL?
Chatham is in USDA Plant Hardiness Zone 6a (average extreme winter low -10°F to -5°F), according to the USDA 2023 map.
When is the last frost in Chatham?
The average last spring frost (32°F) in Chatham is April 15. There is still a 10% chance of frost until April 30.
When can I plant tomatoes in Chatham?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 22 – Apr 29. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Springfield #2, IL (USC00118186), 13.6 km (8.4 mi) from the city center, elevation 183 m, based on 12 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.