Tall annual with massive single yellow flower heads tracking the sun. The seeds feed bees, songbirds and humans alike.
Hardiness ratings
| System | Rating | Temperature range | How to read it |
|---|---|---|---|
| USDA hardiness zone | Zone 2–11 | −45.6 °C to 10 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| RHS hardiness rating | H7 | down to −20 °C | Plant needs at least this level of cold tolerance |
| Canadian plant hardiness zone | Zone 2–9 | −40 °C and warmer | Zones where it can be grown as an annual — not a frost-tolerance rating |
| Australian (ANBG) zone | Zone 1–7 | −15 °C and warmer | Zones where it can be grown as an annual — not a frost-tolerance rating |
As a tender annual, Sunflower doesn't overwinter — the zone range shows where the growing season supports it. See the RHS rating for its actual cold tolerance.
About Sunflower
Sunflowers are North American in origin and were domesticated there long before European contact, and they are one of the few major crops to have been. Young flower buds track the sun across the sky, a movement called heliotropism driven by differential growth on the stem, but this stops once the flower opens — mature heads generally face east and stay there. What looks like one flower is a composite head of hundreds of individual florets, arranged in interlocking spirals whose counts follow a mathematical sequence with striking regularity.
Growing notes
- Outstanding bee forage and a major source of late-summer pollen
- Seed heads are a key autumn and winter food source for finches, tits and other songbirds — leave heads standing
- Choose single-headed open-pollinated varieties — pollen-free double hybrids are useless to pollinators
- Tall varieties make a good seasonal windbreak for vegetable beds
Categories
Related plants
Cross-check Sunflower against your zones