- Species and varieties: Zinnia is a genus of plants of the sunflower tribe within the daisy family (Asteraceae). There are several species of zinnia, with Zinnia elegans being the most commonly grown. Varieties include 'Lilliput', 'State Fair', 'Thumbelina', and 'Dreamland'.
- Hybrid or heirloom: Zinnia seeds can be both hybrid and heirloom. Heirloom varieties are open-pollinated and have been passed down through generations, such as 'Cut and Come Again' and 'Benary's Giant'. Hybrid varieties are bred for specific traits like disease resistance and uniformity, such as 'Profusion' and 'Zahara'.
- Pruning and training: Zinnias require minimal pruning. Deadheading spent flowers encourages continuous blooming. Taller varieties may benefit from staking to prevent them from toppling over in windy conditions.
- Fertilization needs: Zinnias benefit from a balanced, all-purpose fertilizer applied at planting time. Additional feeding with a water-soluble fertilizer every 4-6 weeks can promote vigorous growth and abundant blooms. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of flowers.
- Hardiness zones: Zinnias are suitable for USDA hardiness zones 2-11. They are annuals and will not survive frost, so they are typically grown as summer annuals in most regions.
- Climate requirements: Zinnias thrive in warm climates with full sun exposure. They prefer temperatures between 70-85°F (21-29°C) and require well-drained soil. They are drought-tolerant once established but perform best with regular watering.