When to plant zinnia in zone 8b — planting calendar

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Showing USDA Zone 8B

Growing SeasonZone 8b

Last frost ~Mar 15First frost ~Nov 15Today

Start indoorsTransplant / sowHarvestFrost risk

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Start indoors Feb 15 · Sow Mar 15 · First harvest May 4 · Wrap by Jul 27

Last spring frostMar 15

Start seeds indoorsFeb 15

Direct sowMar 15

First harvestMay 4

Last harvestJul 27

First fall frostNov 15

Why these dates work in zone 8b

Zone 8b's last spring frost averages Mar 15 and first fall frost Nov 15 — about 245 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 15 and first picking around May 4.

Will zinnia survive frost in zone 8b?

No — zinnia is frost-sensitive. In zone 8b, wait until after the last frost (around Mar 15) to plant, and harvest before the first fall frost (around Nov 15).

For soil, spacing, pests and companion planting, see the full zinnia growing guide →