Optimal Planting Times for Planting Broccoli in Illinois

Planting MethodActivityRecommended Dates
Spring PlantingIndoor Seed StartingFebruary 15 – March 15
Transplant OutdoorsApril 1 – May 1
Direct SowingApril 1 – April 15
Fall PlantingIndoor Seed StartingJune 15 – July 15
Transplant OutdoorsAugust 1 – September 1
Direct SowingJuly 15 – August 15

Planting Conditions

Illinois, which spans USDA Hardiness Zones 5a to 7a, has a diverse climate with cold winters and warm, humid summers. This makes both spring and fall suitable for growing broccoli, a crop that prefers cooler temperatures.

Starting Broccoli Indoors

Example: In Chicago, IL (Zone 5b), begin indoor seed starting from mid-February to mid-March. This ensures that seedlings are ready for transplanting outdoors between early April and early May.

  • Required Materials: Seed trays, quality potting mix, grow lights or a sunny window, and a consistent watering routine.
  • Process: Fill seed trays with potting mix, sow seeds ¼ inch deep, keep the soil moist, and provide ample light.

Direct Sowing in the Soil

Example: In Springfield, IL (Zone 6a), direct sow broccoli seeds in the garden from early April to mid-April for a spring harvest, and from mid-July to mid-August for a fall crop.

  • Soil Preparation: Prepare the soil by tilling it finely, incorporating compost, and ensuring good drainage.
  • Sowing Instructions: Plant seeds ½ inch deep, spacing them about 3 inches apart. Once seedlings have several true leaves, thin them to 12-18 inches apart.

Transplanting Broccoli Seedlings

Example: For gardeners in Peoria, IL (Zone 5b), start seeds indoors from mid-June to mid-July and transplant them into the garden from early August to early September.

  • Bed Preparation: Enrich the soil with organic matter and maintain a pH level between 6.0 and 7.0.
  • Transplanting Guidelines: Space seedlings 18-24 inches apart in rows 24-36 inches apart. After transplanting, water thoroughly and apply mulch to help retain soil moisture.

General Care and Maintenance

Watering and Fertilization: Broccoli requires regular watering, especially during dry spells. Water at the base of the plants and use a balanced vegetable fertilizer as needed.

Pest and Disease Management: Monitor for pests such as aphids and cabbage worms. Utilize floating row covers and organic pest control methods as needed. Practice crop rotation and remove plant debris to reduce disease risk.

Harvesting Broccoli: Harvest heads when they are firm and tightly closed, before they start to flower. Cut the main head with part of the stem, and the plant may produce smaller side shoots for additional harvests.


Next, we’ll move on to Indiana.

BeeJay