Tithonia (Mexican Sunflower) in Zone 4a & 4b

Tithonia rotundifolia

When to plant tithonia (mexican sunflower) in zone 4b

Zones 4a and 4b 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 indoorsApr 3–Apr 10
Direct sow / transplant outsideMay 29–Jun 5
Estimated bloomAug 25–Sep 1 (~88 days after planting)

Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 4-6 ft.

Tithonia (Mexican Sunflower)
Photo: Forest & Kim Starr via Wikimedia Commons, CC BY 3.0, cropped.

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 4's season

Zone 4b's frost-free window runs about 128 days, from May 15 to September 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)

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Growing Tithonia (Mexican Sunflower) in USDA zone 4b

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Growing Tithonia (Mexican Sunflower) in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.

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