Plant Eggplant in Zone 10b

Zone 10b averages 350 frost-free days, running from a last spring frost around January 15 to a first fall frost around December 31. Eggplant needs roughly 85 days from planting out to first harvest, so it uses about 24 percent of that window. Eggplant is a tender crop, which is what decides where in the window it belongs.

Because eggplant needs a head start, sow seed indoors around Nov 20, about 8 weeks ahead of the Zone 10b last frost. Transplants go out around Jan 29. Starting earlier than that in Zone 10b usually backfires: plants outgrow their cells and stall when they finally hit cold soil. At 85 days to harvest, a 350-day Zone 10b season has room for about 3 sowings, so stagger them rather than planting everything at once.

Yes. Sow eggplant by September 9 in Zone 10b. That is 113 days before the average first frost, which covers the 85 days to maturity plus about two weeks for the slower growth that comes with shortening days, plus a two week margin because frost kills eggplant outright.

Eggplant needs a long warm run to finish, so a second planting is realistic only in zone 9 and warmer.