Quick planting window
| Start indoors | April to May |
|---|---|
| Transplant | May to June |
| Sow seeds | May to June |
| Estimated harvest | July to August |
| Risk | Medium risk |
Month calendar
Scan the year by month to see seed starting, sowing, transplanting, and harvest timing.
Broccoli is a reasonable spring choice for Colorado if you adjust for your local microclimate.
Next: ZIP code personalization
This is a state-level planning window based on typical frost timing and crop rules. Use local Extension guidance or a ZIP code frost-date tool before planting.
Planning notes
Days to maturity
70
Covered states
Colorado
Frost window
May to June / September to October
Front Range, mountain, and western slope gardens can have very different timing.
Broccoli growing notes
The calendar window is only the first step. These growing details affect survival, plant vigor, and harvest quality.
Sun
Full sun in cool weather.
Soil
Fertile soil with consistent moisture.
Spacing
18-24 inches.
Container
Use 5+ gallon containers for one plant.
Watering
Keep moisture steady to prevent small heads.
Common mistake
Planting into heat that causes early flowering.
Beginner tip
Favor fall planting where summers are hot.
Month window table
| Crop | Spring transplant / sow | Spring harvest | Fall transplant / sow | Fall harvest |
|---|---|---|---|---|
| Broccoli | May to June | July to August | July to August | September to October |
Sources and limits
This page uses Colorado state-level frost windows, USDA zone ranges, and crop rules for planning. It does not replace local Extension or county-level guidance.
FAQ
When should I start broccoli seeds indoors in Colorado?
For spring, the indoor seed-starting window is about April to May. Move later if your local frost date is later than the state average.
When should I transplant broccoli in Colorado?
For spring, the transplant window is about May to June. Harden seedlings off before planting outside.
Can I sow broccoli outdoors in Colorado?
Yes. The spring outdoor sowing window is about May to June, assuming soil and night temperatures are suitable.
When can I harvest broccoli in Colorado?
Spring planting estimates a harvest around July to August; fall planting estimates about September to October. Variety and weather can shift this by several weeks.
Is broccoli risky in Colorado?
Broccoli is a reasonable spring choice for Colorado if you adjust for your local microclimate. For fall: Broccoli is a reasonable fall choice for Colorado if you adjust for your local microclimate.
Do local differences inside Colorado matter?
Front Range, mountain, and western slope gardens can have very different timing. Treat this as a state-level starter window and confirm with a local Extension or frost-date tool before planting.
What growing details matter most for broccoli?
Full sun in cool weather. Fertile soil with consistent moisture. Common mistake: Planting into heat that causes early flowering.
Is this ZIP-code accurate?
No. This page uses state-level windows; ZIP-code frost dates, USDA zone matching, and reminder calendars are planned for the next phase.