Mexican Sunflower — Growing reference
| Scientific name | Tithonia rotundifolia |
|---|---|
| Seed germination (days) | 5–10 |
| Soil temperature for germination (°C) | 21.1–29.4 |
| First harvest or flowering (days) | 75–90 |
| Measured from | Transplant |
| Plant spacing (cm) | 61–91.4 |
| Mature height (cm) | 121.9–182.9 |
| Mature spread (cm) | 61–91.4 |
| USDA hardiness zones | 2–11 |
| Light | Full sun |
| Water | Low |
| Sowing method | Transplant |
Growing directions
Start indoors 4–6 weeks before transplanting (after soil warms to 70°F+) in well-drained, average to poor, neutral soil in full sun; tithonia is extremely heat- and drought-tolerant once established and actually blooms better in lean, dry soil. Tithonia rotundifolia is the premier late-summer annual for attracting monarch butterflies, swallowtails, and native bumblebees — in high summer and early fall, a patch of blooming Mexican sunflowers will be covered with butterflies from dawn to dusk. The plant produces vivid, velvety, 3-inch, orange-scarlet flowers with a golden-yellow center on tall, branching, slightly hairy stems from midsummer through frost; hollow stems must be seared before using as cut flowers to prevent wilting. It is an outstanding back-of-border annual for hot, sunny gardens in zones 9–11 and is perennial in frost-free areas.
Source and local conditions
Typical planning ranges from OpenPlantDB (CC0). Cultivar, climate, season and growing method can change these values. Confirm the seed label and local guidance before planting.
OpenPlantDB · tithonia-rotundifolia
Source & verification
OpenPlantDB · CC0