Decatur, IL planting zone & frost dates
Decatur is in USDA hardiness zone 6a. The last spring frost usually comes around April 14 and the first fall frost around October 24, for a growing season of about 192 days.
Planting calendar for Decatur
Dates are counted from the average last spring frost (April 14) 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 17 – Mar 3 Transplant outdoors: Apr 21 – Apr 28 |
| Peppers | Start seeds indoors: Feb 3 – Feb 17 Transplant outdoors: Apr 28 – May 5 |
| Eggplant | Start seeds indoors: Feb 3 – Feb 17 Transplant outdoors: Apr 28 – May 5 |
| Broccoli | Start seeds indoors: Feb 3 – Feb 17 Transplant outdoors: Mar 17 – Mar 31 |
| Cabbage | Start seeds indoors: Feb 3 – Feb 17 Transplant outdoors: Mar 17 – Mar 31 |
| Onions (sets) | Plant outdoors: Mar 17 – Mar 31 |
| Peas | Sow outdoors: Mar 3 – Mar 17 |
| Spinach | Sow outdoors: Mar 3 – Mar 17 |
| Lettuce | Sow outdoors: Mar 17 – Mar 31 |
| Carrots | Sow outdoors: Mar 17 – Mar 31 |
| Potatoes | Plant outdoors: Mar 17 – Mar 31 |
| Beans | Sow outdoors: Apr 21 – Apr 28 |
| Sweet corn | Sow outdoors: Apr 21 – Apr 28 |
| Cucumbers | Sow outdoors: Apr 21 – Apr 28 |
| Squash & zucchini | Sow outdoors: Apr 21 – Apr 28 |
| Basil | Start seeds indoors: Mar 3 – Mar 17 Transplant outdoors: Apr 21 – Apr 28 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 29 (8 weeks before the average first fall frost on Oct 24).
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 1 | Apr 14 | May 1 |
| First 32°F frost in fall is before | Nov 5 | Oct 24 | Oct 11 |
How to read it: in spring there is a 10% chance of a frost after May 1, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 11. A hard freeze (28°F) usually ends around April 3.
Hardiness zone by ZIP code in Decatur
- 62521 zone 6a
- 62522 zone 6a
- 62523 zone 6a
- 62524 zone 6a
- 62525 zone 6a
- 62526 zone 6a
Nearby cities
- Taylorville zone 6a, last frost Apr 12
- Lincoln zone 6a, last frost Apr 20
- Bloomington zone 6a, last frost Apr 21
- Normal zone 6a, last frost Apr 25
- Mattoon zone 6a, last frost Apr 11
- Springfield zone 6a, last frost Apr 15
- Champaign zone 6a, last frost Apr 15
- Chatham zone 6a, last frost Apr 15
Questions
What growing zone is Decatur, IL?
Decatur 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 Decatur?
The average last spring frost (32°F) in Decatur is April 14. There is still a 10% chance of frost until May 1.
When can I plant tomatoes in Decatur?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 21 – Apr 28. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Decatur Wtp, IL (USC00112193), 1.3 km (0.8 mi) from the city center, elevation 195 m, based on 24 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.