When to Plant Turnips in Illinois
Published: April 24, 2026
Illinois gardeners in Zone 5b have a 28-week frost-free window for turnip (April 7 to October 22). Cool-season crops like turnip do well here because the short, cool summers match the plant's temperature preferences naturally. This guide gives exact dates for Illinois based on your local frost calendar.
Turnip Planting Dates for Illinois
| Start seeds indoors | Year-round |
| Last frost (average) | April 7 |
| Direct sow outdoors | March 17–27 |
| Expect first harvest | April 21 – May 16 |
| Fall crop start | August 27–September 6 |
| Fall harvest | October 1 |
| First fall frost (average) | October 22 |
Dates above assume Zone 5b, the most common zone in Illinois. Gardeners in cooler Chicago (Zone 5b) plant 1–2 weeks later; warmer Peoria (Zone 6a) can plant 1–2 weeks earlier.
⚠ Direct sow turnips 2–4 weeks before last frost for spring crop. Best planted in late summer (6–8 weeks before first fall frost) for fall harvest — frost sweetens the roots. Fast-growing: some varieties ready in just 35 days.
Growing Turnips in Illinois's Climate
Illinois's cold Zone 5b climate is close to ideal for turnip. The cool springs and moderate summers match the plant's natural temperature preferences, producing crisp, sweet, slow-bolting harvests that hot-climate gardeners cannot grow.
The fall turnip crop in Illinois is often better than the spring crop. Plants mature as temperatures cool in September and October, concentrating sugars and tightening heads or roots. Light frost can improve flavor; hard frost signals harvest time.
Common turnip pests to watch for in Illinois include Flea Beetle and Aphid. The first line of defense is companion planting: Pea and Mint planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Turnip Garden Calendar for Illinois
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | — | Dormant season |
| March | Direct sow seeds | Sow seeds 1/4–1/2 inch deep, 4 inches apart |
| April | First harvest window opens | Turnip begins producing 35–60 days after transplant |
| May ← | Watch for bolting | Harvest promptly; spring heat arrives quickly |
| June | — | Dormant season |
| July | — | Dormant season |
| August | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| September | — | Dormant season |
| October | First frost approaches | Harvest remaining turnip; cover plants on frost nights |
| November | — | Dormant season |
| December | — | Dormant season |
Turnip Growing Tips for Illinois Gardeners
- •Thin seedlings to 4-inch spacing when plants are 3 inches tall — crowded turnips produce small woody roots.
- •Both roots AND greens are edible — harvest baby turnip greens 4 weeks after sowing, roots 5–9 weeks.
- •Illinois's short growing season means start seeds indoors under grow lights — don't rely on windowsill light which produces leggy, weak seedlings that struggle outdoors.
- •Cover young transplants with floating row covers for the first 2–3 weeks outside. The 3–5°F of protection reduces frost damage risk and accelerates early growth.
- •Fall turnips are sweetest — plant 8 weeks before first frost and let cold weather convert starches to sugars.
Companion Planting for Turnips in Illinois
In Illinois's cold climate, planting turnip with Pea and Mint helps deter pests and improve soil. Avoid planting near Potato and Radish, which inhibit turnip growth through root chemistry or shared pest pressure. See the full turnip companion planting guide for the complete list.
Turnips Planting Dates by City in Illinois
Top cities in Illinois — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant turnip in Illinois?
In Illinois (Zone 5b), start turnip seeds indoors around Year-round and transplant outdoors around null — 0 weeks after the state's average last frost of April 7.
What is the last frost date in Illinois?
Illinois's average last frost date is April 7 in the state's most common Zone 5b. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow turnip year-round in Illinois?
turnip is a cool-season crop in Illinois, with spring and fall windows. Summer heat bolts the plants before they can produce a harvestable crop. Succession planting every 2–3 weeks stretches the harvest window.
What turnip varieties grow best in Illinois?
For Illinois's Zone 5b, consult a local nursery or extension office for turnips variety recommendations.
When do I start turnip seeds indoors in Illinois?
Turnip does not need indoor starting in Illinois — direct sow around March 17–27 once soil reaches 40°F. Indoor starting is not recommended for this crop because turnip transplants poorly.