When to Plant Broccoli in Chicago, IL
Published: April 21, 2026
Broccoli Planting Dates for Chicago, IL
| Start seeds indoors | February 24–March 3 |
| Last frost (average) | April 7 |
| Transplant outdoors | March 10–20 |
| Direct sow outdoors | March 10–20 |
| Minimum soil temperature | 40°F |
| Expect first harvest | May 9 – May 29 |
| Fall crop planting | August 13–23 |
| Fall crop harvest | October 12 |
| First fall frost (average) | October 22 |
Best Broccoli Varieties for Chicago, IL
For Zone 5b Chicago, the best-performing broccoli varieties are Arcadia, Belstar, and Diplomat — all short-season varieties chosen for cool-climate reliability. These varieties are typically stocked by local nurseries and are the safest bets for gardeners new to broccoli in Chicago.
Growing Broccoli in Chicago
Chicago sits in Zone 5b, with an average last frost of April 7 and first fall frost around October 22 — giving a 198-day frost-free growing season. Cool-season crops like broccoli benefit from Chicago's cooler spring and fall windows, when temperatures stay in the 55–75°F sweet spot that produces the best flavor and least bolting.
Chicago's cooler summers are close to ideal for broccoli. The same conditions that limit tomato and pepper yields benefit cool-season crops — slower bolting, sweeter flavor, and longer harvest windows. The fall broccoli crop in Chicago is often more productive than the spring crop.
Chicago's clay-loam soils are productive but benefit from annual compost amendment — 2 to 3 inches worked in before planting improves drainage and nutrient availability for broccoli. Consistent watering (1.5 inches per week) paired with organic mulch maintains the even moisture that clay-loam holds well. Avoid working wet soil in spring, which causes severe compaction in clay-loam blends.
Broccoli Calendar for Chicago
| Month | Task |
|---|---|
| February | Start seeds indoors under grow lights |
| April | Last frost — harden off seedlings outdoors |
| March | Transplant outdoors into warm soil |
| May | Expect first harvest window to open |
| August | Start fall crop — transplants or direct sow |
| October | First fall frost — harvest remaining, end of outdoor season |
Broccoli Tips for Chicago Gardeners
- •For spring: start indoors 6 weeks before last frost and transplant outdoors 4 weeks before last frost.
- •For fall: start indoors in summer — count 10 weeks back from your first fall frost date.
- •Fall plantings in Chicago often out-produce spring plantings — cooler temperatures slow bolting and concentrate flavor. Light frost can actually improve the taste of broccoli.
Common Broccoli Pests in Chicago
- •Cabbage Worm — peaks July in Zone 5b (active June–August); green caterpillars on brassicas; apply Bt spray or use row covers.
- •Cabbage Looper — peaks July in Zone 5b (active June–August); loop-walking green caterpillars; Bt spray works well.
- •Aphids — peaks July in Zone 5b (active June–August); clusters on leaf undersides; blast with a strong water spray or apply neem oil.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Broccoli in Chicago
In Chicago's cold climate, Onion and Garlic are the most beneficial plants to grow alongside broccoli. Onion deters carrot fly, aphids, and several root-zone pests through sulfur compounds. Keep broccoli away from Tomato — it competes for nutrients or shares pest pressure. In short-season gardens, interplanting companions at transplant time maximizes each bed's productive weeks.
Frequently Asked Questions
When should I plant broccoli in Chicago, IL?
In Chicago (Zone 5b), start broccoli seeds indoors around February 24–March 3 and transplant outdoors around March 10–20. The city's average last frost of April 7 is the anchor date — count 6 weeks back for seed starting and 4 weeks back for transplanting.
What zone is Chicago, IL for broccoli growing?
Chicago is USDA Zone 5b. For broccoli, this means a frost-free growing season of roughly 28 weeks running from April 7 to October 22. Cool-season crops like broccoli thrive in this zone with both spring and fall planting windows available.
When is broccoli harvest season in Chicago?
Expect the first broccoli harvest in Chicago around May 9, with harvest continuing through May 29. This is based on 60–80 days from transplant or direct sow. A fall crop planted August 13–23 adds a second harvest around October 12.
How long does it take to grow broccoli in Chicago, IL?
From transplant or direct sow to first harvest, broccoli takes 60–80 days in Chicago's climate. Based on a typical planting date of March 10–20, expect your first harvest around May 9. Chicago's cooler Zone 5b climate often lands at the slower end of this range — cooler nights slow fruit development.
What soil does broccoli need in Chicago?
Chicago's clay-loam soil is productive for broccoli but benefits from annual compost amendment. Work 2–3 inches of compost into the top 10 inches before planting. Avoid working wet soil in spring — clay-loam compacts badly when wet. Consistent watering paired with organic mulch maintains the even moisture these soils hold well.