Zone 9b covers 17 days of last-frost dates. We measured Las Vegas, NV at Feb 6 and Sacramento, CA at Feb 23. 10 of the 15 places we checked in this zone don't dependably freeze at all. Give us your town or ZIP and we'll use ten years of daily lows recorded at your own coordinates instead of the middle of that range.
Why these dates work in zone 9b
Zone 9b's last spring frost averages Feb 9 and first fall frost Dec 8 — about 302 frost-free days. Basil is frost-sensitive, so the 2w after frost timing builds in a safety margin against a late cold snap — setting plants out too early risks losing them to frost. Starting seeds indoors 4 weeks ahead gives strong transplants ready the moment the soil warms.
Common questions
How long does basil take to grow in zone 9b?
Basil matures in about 25–35 days from sowing. In zone 9b that means sowing around Feb 23 and first picking around Mar 20.
Will basil survive frost in zone 9b?
No — basil is frost-sensitive. In zone 9b, wait until after the last frost (around Feb 9) to plant, and harvest before the first fall frost (around Dec 8).
For soil, spacing, pests and companion planting, see the full basil growing guide →