Tithonia (Mexican Sunflower) in Zone 8a & 8b
Tithonia rotundifolia
Yes, tithonia (Mexican sunflower) grows in zones 8a and 8b. Start seeds indoors Feb 11–Feb 18 and plant out Apr 8–Apr 15.
When to plant tithonia (Mexican sunflower) in zone 8b
Zones 8a and 8b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Start indoors | Feb 11–Feb 18 |
|---|---|
| Direct sow / transplant outside | Apr 8–Apr 15 |
| Estimated bloom | Jul 5–Jul 12 (~88 days after planting) |
Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 4-6 ft.
Plant alongside it in zone 8b
These go outside within two weeks of tithonia (Mexican sunflower) in zone 8b, so one planting day can cover them.
- NasturtiumApr 1–Apr 8
- MarigoldApr 1–Apr 8
- Angelonia (Summer Snapdragon)Apr 8–Apr 15
- Bee BalmApr 8–Apr 15
- Black-Eyed Susan VineApr 8–Apr 15
- Chrysanthemum (Garden Mum)Apr 8–Apr 15
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 8's season
Zone 8b's frost-free window runs about 230 days, from March 25 to November 10. Tithonia (Mexican sunflower) needs about 88 days from sowing to first bloom.
Tithonia (Mexican Sunflower) planting windows in every zone
Zone 8b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 8–Apr 15 | Jun 3–Jun 10 | Aug 30–Sep 6 |
| 3a & 3b | Apr 18–Apr 25 | Jun 13–Jun 20 | Sep 9–Sep 16 |
| 4a & 4b | Apr 3–Apr 10 | May 29–Jun 5 | Aug 25–Sep 1 |
| 5a & 5b | Mar 29–Apr 5 | May 24–May 31 | Aug 20–Aug 27 |
| 6a & 6b | Mar 14–Mar 21 | May 9–May 16 | Aug 5–Aug 12 |
| 7a & 7b | Feb 27–Mar 6 | Apr 24–May 1 | Jul 21–Jul 28 |
| 8a & 8b (your zone) | Feb 11–Feb 18 | Apr 8–Apr 15 | Jul 5–Jul 12 |
| 9a & 9b | Jan 4–Jan 11 | Mar 1–Mar 8 | May 28–Jun 4 |
| 10a & 10b | Dec 19–Dec 26 | Feb 13–Feb 20 | May 12–May 19 |
| 11a & 11b | Nov 20–Nov 27 | Jan 15–Jan 22 | Apr 13–Apr 20 |
Bloom dates are about 88 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for tithonia (Mexican sunflower).
Where to buy tithonia seeds
True Leaf Market · Burpee (each supplier's tithonia seeds)
Varieties we recommend, and where to get them:
- 'Goldfinger': The smallest of the three per Clemson, orange-gold flowers on a 2-2.5 foot plant, an even more compact option than Fiesta del Sol for the tightest spaces. Buy: True Leaf Market Full notes
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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 8b calendar · Plan your beds in the Garden Designer →
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Growing Tithonia (Mexican Sunflower) in USDA zone 8b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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