Plant Broccoli in Zone 8b

Zone 8b averages 245 frost-free days, running from a last spring frost around March 15 to a first fall frost around November 15. Broccoli needs roughly 65 days from planting out to first harvest, so it uses about 27 percent of that window. Broccoli is a half-hardy crop, which is what decides where in the window it belongs.

Because broccoli needs a head start, sow seed indoors around Feb 1, about 6 weeks ahead of the Zone 8b last frost. Transplants go out around Mar 1. Starting earlier than that in Zone 8b usually backfires: plants outgrow their cells and stall when they finally hit cold soil. At 65 days to harvest, a 245-day Zone 8b season has room for about 3 sowings, so stagger them rather than planting everything at once.

Yes. Sow broccoli by September 18 in Zone 8b. That is 58 days before the average first frost, which covers the 65 days to maturity plus about two weeks for the slower growth that comes with shortening days, minus the roughly 21 days broccoli keeps going once light frost arrives.

Fall broccoli avoids the spring problem of heads buttoning up when temperatures spike. Start transplants indoors in midsummer rather than direct sowing into hot soil.