Zone 8b covers 47 days of last-frost dates. We measured Fort Worth, TX at Feb 18 and Eugene, OR at Apr 6. 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 8b
Zone 8b's last spring frost averages Mar 6 and first fall frost Nov 22 — about 261 frost-free days. Zinnia is frost-sensitive, so the around last 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 zinnia take to grow in zone 8b?
Zinnia matures in about 50–70 days from sowing. In zone 8b that means sowing around Mar 6 and first picking around Apr 25.
Will zinnia survive frost in zone 8b?
No — zinnia is frost-sensitive. In zone 8b, wait until after the last frost (around Mar 6) to plant, and harvest before the first fall frost (around Nov 22).
For soil, spacing, pests and companion planting, see the full zinnia growing guide →