USDA Zone 13 planting calendar
When to plant thyme 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 thyme in zone 13
| Stage | When | Anchor |
|---|---|---|
| Plant outdoors | year-round (avoid the hottest 6-8 weeks of summer for heat-sensitive varieties) | No frost — plant in the cool months |
| First harvest (estimate) | ~85 days after planting | ~85 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.
Start seeds indoors 8–10 weeks before the last spring frost; germination takes 14–21 days at 18–21 °C (65–70 °F). Harden off transplants and set out around the date of last frost — thyme is perennial in USDA zones 5–9 (RHS H5) but resents waterlogged soil far more than cold. In the first growing season allow only light harvesting so the plant can establish; full harvests from the second year onward, cutting stems back to 4–5 cm above woody growth.
Quick-grow guide
- Sun: Full sun — 6+ hours direct.
- Soil temperature for germination: 18–21 °C (65–70 °F).
- Spacing: 6–8 inches (15–20 cm) between plants.
- Days to harvest from direct sow: ~85 days.
- Wait until night temperatures stay above 10 °C — cold soil stunts warm-season crops permanently.
Common mistakes — zone 13 × thyme
- Planting before last frost: zone 13's last frost averages no frost, and even a light frost will kill thyme seedlings overnight.
- Skipping hardening off: even healthy indoor transplants need 7-10 days of progressive outdoor exposure before going in the ground.
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 thyme — full guide
- USDA Zone 13 — frost dates and what else to plant
- All 13 USDA hardiness zones