USDA Zone 9 planting calendar
When to plant kohlrabi in USDA zone 9
Sowing, transplant, and harvest dates calibrated to zone 9's 280-day season (Central + South Florida, Southern Texas, Southern California, Arizona).
Key dates for kohlrabi in zone 9
| Stage | When | Anchor |
|---|---|---|
| Indoor seed start | mid-January (January 20) | 5 weeks before last frost |
| Outdoor transplant | early February (February 3) | 21 days before last frost (mid-February to early March) |
| First harvest (estimate) | late March (March 30) | ~55 days from transplant |
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 9
Zone 9 has average annual minimum temperatures of 20 to 30°F and a 280-day frost-free window from mid-February to early March to late November / early December. Kohlrabi 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 9.
Kohlrabi is a fast-maturing brassica that tolerates light frost down to about -4 °C but turns woody and pithy when daytime temperatures exceed 27 °C; transplant or direct-sow 3–4 weeks before the last spring frost for a summer harvest, or time a second sowing so plants mature in the cool days of early autumn. Harvest promptly when the swollen stem reaches 5–7 cm (2–3 inches) in diameter — larger bulbs become fibrous. Succession-sow every 3 weeks to extend the harvest window.
Quick-grow guide
- Sun: Full sun — 6+ hours direct.
- Soil temperature for germination: 7-29 °C (45-85 °F).
- Spacing: 6-9 inches (15-23 cm) between plants.
- Days to harvest from transplant: ~55 days.
- Plant in cool weather and provide afternoon shade once temperatures climb above 24 °C.
Common mistakes — zone 9 × kohlrabi
- Spring planting: zone 9 springs are too short — sow kohlrabi 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 kohlrabi — full guide
- USDA Zone 9 — frost dates and what else to plant
- All 13 USDA hardiness zones
Same crop, nearby zones
- When to plant kohlrabi in USDA zone 7
- When to plant kohlrabi in USDA zone 8
- When to plant kohlrabi in USDA zone 10
- When to plant kohlrabi in USDA zone 11