Plant Cilantro in Zone 9b

Zone 9b averages 298 frost-free days, running from a last spring frost around February 15 to a first fall frost around December 10. Cilantro needs roughly 45 days from planting out to first harvest, so it uses about 15 percent of that window. Cilantro is a half-hardy crop, which is what decides where in the window it belongs.

Cilantro handles cold soil, so there is no reason to wait for the frost date. Direct sow around Feb 1, roughly 2 weeks before the Zone 9b last frost, as soon as the ground is workable. Sowing at the last frost instead costs you the coolest and best part of the season. At 45 days to harvest, a 298-day Zone 9b season has room for about 5 sowings, so stagger them rather than planting everything at once.

Yes. Sow cilantro by October 26 in Zone 9b. That is 45 days before the average first frost, which covers the 45 days to maturity plus about two weeks for the slower growth that comes with shortening days, minus the roughly 14 days cilantro keeps going once light frost arrives.

Cilantro bolts within weeks in summer heat and is far more productive as a fall crop, and in mild zones it runs right through winter.