USDA Zone 13 planting calendar
When to plant kale in USDA zone 13
Sowing, transplant, and harvest dates calibrated to zone 13's 365-day season (Hawaii (coastal lowlands), Puerto Rico (south coast)).
Key dates for kale in zone 13
| 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) | ~60 days after sowing | ~60 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 13
Zone 13 has average annual minimum temperatures of 60 to 70°F and a 365-day frost-free window from no frost to no frost. Kale 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 13.
Kale is among the hardiest brassicas, surviving temperatures as low as −12 °C (10 °F) in protected conditions; frost sweetens the leaves by converting starches to sugars. Transplant or direct-sow 4–6 weeks before last spring frost; can also be direct-sown. For fall/winter harvest, direct-sow or transplant 6–8 weeks before first autumn frost. Avoid planting when temperatures consistently exceed 27 °C (80 °F) as heat reduces palatability and increases bitterness. Harvest outer leaves continuously to extend production; the plant does not form a head and can be harvested over many months.
Quick-grow guide
- Sun: Full sun to part shade — 4–6+ hours direct.
- Soil temperature for germination: 7–29 °C (45–85 °F).
- Spacing: 12–18 inches (30–45 cm) between plants.
- Days to harvest from direct sow: ~60 days.
- Plant in cool weather and provide afternoon shade once temperatures climb above 24 °C.
Common mistakes — zone 13 × kale
- Spring planting: zone 13 springs are too short — sow kale 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 kale — full guide
- USDA Zone 13 — frost dates and what else to plant
- All 13 USDA hardiness zones