Illinois stretches about 400 miles north to south. Chicago-area gardeners face later last frost dates than those in southern Illinois near Cairo, often by a full month. Southern Illinois warms up significantly earlier.
The state's prairie soils are among the richest in the world, which is great news for vegetable gardeners. Most of Illinois has deep, fertile soil that produces excellent crops with minimal amendments.
The last frost date is the typical date in spring when your area has its final frost. After this date, it's generally safe to plant warm-season crops outdoors.
Start tomato seeds indoors about 6–8 weeks before your last frost date. In the Chicago area, that's usually late March. In southern Illinois, you can start in early March.
Yes — cool-season crops like lettuce, peas, spinach, and broccoli can handle light frost and should be planted 4–6 weeks before your last frost date.
The 400-mile north-to-south span means southern Illinois has a much longer season than the Chicago area. Lake Michigan also affects spring temperatures in the northeast.
Illinois doesn't have frost-free areas, but southern Illinois near the Ohio River has a significantly longer growing season. Enter your zip code for exact frost dates.
You enter your zip code, and we look up your local frost dates. Then based on the crops you pick, we calculate when to start seeds, transplant, and harvest — personalized to your location.