Planting calendar
When to plant broccoli in Colorado
Colorado spans USDA hardiness zones 3-7a. Average last spring frost: 05-15. This calendar gives you the indoor start, transplant, and direct-sow dates for Brassica oleracea var. italica.
Colorado planting dates for broccoli
| Phase | Date in Colorado | Notes |
|---|---|---|
| Start seeds indoors | March 20 | 8 weeks before last frost |
| Transplant outdoors | May 1 | 2 weeks before last frost |
Why these dates
Broccoli is cool-season. Spring crop: transplants in early spring. Fall crop (often better): transplants 8-10 weeks before first fall frost. Row covers prevent cabbage worm damage.
The dates above are anchored to Colorado's average last spring frost date of 05-15, with offsets standard across university Extension publications. For zone-specific local timing, use the frost date lookup tool with your ZIP code.
More on growing broccoli
The full growing guide for broccoli - varieties, soil, fertilization, pests, harvest, storage - is here: Broccoli growing guide.
More Colorado planting information
- Full Colorado planting calendar (all crops + ornamentals)
- Find your exact USDA zone by ZIP
- Look up your average frost dates
- Seed starting timeline calculator