USDA Zone 12 planting calendar
When to plant broccoli in USDA zone 12
Sowing, transplant, and harvest dates calibrated to zone 12's 365-day season (Hawaii (lowland), Puerto Rico (parts)).
Key dates for broccoli in zone 12
| Stage | When | Anchor |
|---|---|---|
| Direct sow outdoors | October — February (the cool dry season is your spring) | No frost — plant in the cool months |
| First harvest (estimate) | ~80 days after sowing | ~80 days from sow |
Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the planting window by 1-2 weeks within the same zone.
Why this timing works for zone 12
Zone 12 has average annual minimum temperatures of 50 to 60°F and a 365-day frost-free window from no frost to no frost. Broccoli are hardy enough to handle light frost — and in fact prefer cool weather. They bolt or turn bitter once daytime temperatures consistently climb above 24 °C, which is why earlier is better in zone 12.
Start seeds indoors 6–8 weeks before last frost; transplant outdoors 2–4 weeks before last spring frost when soil reaches at least 7 °C (45 °F). Mature plants withstand temperatures as low as −6 °C (21 °F). Heads button (form premature small curds) when exposed to temperatures below 10 °C (50 °F) for extended periods as young seedlings, so harden off carefully. In zones 8–10, a second crop is practical as a fall planting, set out in late summer for harvest before hard freezes.
Quick-grow guide
- Sun: Full sun — 6+ hours direct.
- Soil temperature for germination: 7–29 °C (45–85 °F).
- Spacing: 18–24 inches (45–60 cm) between plants.
- Days to harvest from direct sow: ~80 days.
- Plant in cool weather and provide afternoon shade once temperatures climb above 24 °C.
Common mistakes — zone 12 × broccoli
- Spring planting: zone 12 springs are too short — sow broccoli in autumn for a winter and early-spring harvest instead.
- Waiting for "warm" soil — these crops germinate at 7-10 °C and bolt the moment summer heat sets in.
Source and methodology
Frost-date averages from NOAA Climate Data Online within each USDA hardiness zone. Hardiness zone boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing offsets calibrated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS) and cross-checked against the RHS sowing calendar for en-GB readers. Curated by the Growli editorial team.
Keep going
- How to grow broccoli — full guide
- USDA Zone 12 — frost dates and what else to plant
- All 13 USDA hardiness zones
Same crop, nearby zones
- When to plant broccoli in USDA zone 10
- When to plant broccoli in USDA zone 11
- When to plant broccoli in USDA zone 13