Tithonia (Mexican Sunflower) in Zone 10a & 10b
Tithonia rotundifolia
When to plant tithonia (mexican sunflower) in zone 10b
Zones 10a and 10b share the same average frost dates in our data, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Tithonia (Mexican Sunflower) tolerates either.
| Start indoors | Dec 19–Dec 26 |
|---|---|
| Direct sow / transplant outside | Feb 13–Feb 20 |
| Estimated bloom | May 12–May 19 (~88 days after planting) |
Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 4-6 ft.

Tithonia, better known as Mexican sunflower, is a fast-growing, heat-loving annual that produces vivid orange-red blooms on tall, sturdy stems late in the season, just as many other cut flowers are winding down.
How tithonia (mexican sunflower) fits zone 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Tithonia (Mexican Sunflower) needs about 88 days from sowing to first harvest.
Good companions
No standout companions recorded yet for Tithonia (Mexican Sunflower).
Where to buy tithonia seeds
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See it growing
Search YouTube for "growing tithonia (mexican sunflower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 10b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Tithonia (Mexican Sunflower) in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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