A broccoli plant

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

Colorado’s Planting Conditions

USDA Hardiness zone map Northern Colorado

Colorado’s climate ranges from USDA Hardiness Zones 3a to 7a, which means it experiences cold winters and warm summers. Precise timing for planting is essential to avoid the extremes of weather.

Starting Broccoli Indoors

Example: In Denver, CO (Zone 5b), start broccoli seeds indoors from early February to early March. This allows you to transplant seedlings outside from mid-April to mid-May.

  • What You’ll Need: Seed trays, high-quality potting mix, grow lights or a sunny window, and a consistent watering schedule.
  • How to Do It: Fill seed trays with potting mix, sow seeds about ¼ inch deep, keep the soil moist, and ensure they get plenty of light.

Other planting guides for Colorado:

Any questions on growing broccoli? Visit our forum to discuss: Growing Broccoli

Direct Sowing in the Soil

Example: In Colorado Springs, CO (Zone 5a), you can sow seeds directly in the garden from early April to early May for a spring crop, and from early July to early August for a fall crop.

  • Preparing the Soil: Work the soil until it’s fine, mix in some compost, and ensure good drainage.
  • Sowing Seeds: Plant seeds ½ inch deep, spaced about 3 inches apart. Once seedlings have a few true leaves, thin them to 12-18 inches apart.

Transplanting Broccoli Seedlings

Example: For gardeners in Fort Collins, CO (Zone 5b), start seeds indoors in early February and transplant them into the garden from mid-April to mid-May.

  • Preparing the Garden Bed: Make sure the soil is rich in organic matter and has a pH between 6.0 and 7.0.
  • Transplanting Technique: Space seedlings 18-24 inches apart in rows 24-36 inches apart. Water thoroughly after transplanting and apply mulch to retain moisture.

General Care and Maintenance

Watering and Feeding: Broccoli requires consistent moisture, especially during dry spells. Water at the base to avoid wetting the leaves, and use a balanced vegetable fertilizer as needed.

Pest and Disease Management: Be aware of pests like aphids and cabbage worms. Use floating row covers and organic pesticides if necessary. Rotate crops and remove plant debris to prevent disease.

Harvesting Broccoli: Harvest the heads when they are firm and tight, before the flowers start to open. Cut the main head with part of the stem attached, and the plant will often produce smaller side shoots for a continued harvest.

Other planting guides for Colorado:

Any questions on growing broccoli? Visit our forum to discuss: Growing Broccoli

BeeJay
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