Zinnias are warm-season annuals with flower forms ranging from open daisies to pom-poms and cactus-like doubles. Cultivars come in nearly every flower colour except true blue.
- Plant after frost danger in full sun and well-drained soil. They dislike cold, wet conditions.
- Direct-sow or start indoors only a few weeks before transplanting. Follow the packet: dwarf edging plants and metre-tall cut flowers need very different spacing.
- Water at soil level and allow air to move between plants. Wet leaves and crowding encourage powdery mildew and other disease.
- Deadhead to continue bloom. Open, single-flowered varieties are easier for bees and other pollinators to use than very dense doubles.
- Taller cultivars make good cut flowers and may need support in wind.
Zinnia seed is easy to save once a flower head is completely brown and dry. Open-pollinated plants may resemble their parents, while hybrids may produce a colourful surprise. Neither result is “inferior”; it is simply genetics at work.