Planting calendar
When to plant zucchini 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 Cucurbita pepo.
Colorado planting dates for zucchini
| Phase | Date in Colorado | Notes |
|---|---|---|
| Start seeds indoors | April 24 | 3 weeks before last frost |
| Transplant outdoors | May 22 | 1 weeks after last frost |
| Direct sow outside | May 22 | 1 weeks after last frost |
Why these dates
Zucchini germinates fast in warm soil. Squash vine borer is the main killer in the eastern US - row covers until flowering, then hand-pick adults in late June.
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 zucchini
The full growing guide for zucchini - varieties, soil, fertilization, pests, harvest, storage - is here: Zucchini 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