When to plant zinnia in zone 10b — planting calendar

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Showing USDA Zone 10B

Growing SeasonZone 10b

Last frost ~Jan 15First frost ~Dec 31Today

Start indoorsTransplant / sowHarvestFrost risk

DECJANFEBMARAPRMAYJUN

Start indoors Dec 18 · Sow Jan 15 · First harvest Mar 6 · Wrap by May 29

Last spring frostJan 15

Start seeds indoorsDec 18

Direct sowJan 15

First harvestMar 6

Last harvestMay 29

First fall frostDec 31

Why these dates work in zone 10b

Zone 10b's last spring frost averages Jan 15 and first fall frost Dec 31 — about 350 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 10b?

Zinnia matures in about 50–70 days from sowing. In zone 10b that means sowing around Jan 15 and first picking around Mar 6.

Will zinnia survive frost in zone 10b?

No — zinnia is frost-sensitive. In zone 10b, wait until after the last frost (around Jan 15) to plant, and harvest before the first fall frost (around Dec 31).

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