Plant Spinach 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. Spinach needs roughly 45 days from planting out to first harvest, so it uses about 15 percent of that window. Spinach is a hardy crop, which is what decides where in the window it belongs.

Spinach handles cold soil, so there is no reason to wait for the frost date. Direct sow around Jan 11, roughly 5 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. Plant spinach between October 29 and November 12 in Zone 9b, roughly 6 to 4 weeks before the average first frost, so it roots before the ground freezes.

Spinach sown 4 to 6 weeks before the first frost sizes up, stalls through winter under a row cover, and restarts weeks before anything can be sown in spring.