Z. elegans ‘Cut and Come Again’, 36 to 42 in. tall
Photo/Illustration: Rosalind Creasy
Zinnia spp. and cvs.
Origin: Roughly 20 annual and perennial species belong to this genus, which is native to the southern United States, Mexico, and South America.
Conditions: Zinnias require rich, well-drained soil in full sun. They are generally heat and drought tolerant. Do not plant them outdoors until night temperatures reach above 50°F. Space plants 10 to 12 inches apart at planting time to give them room to grow and to allow for good air circulation, which will make plants less susceptible to diseases.
Pests and Diseases: Powdery mildew tends to be the biggest disease problem, especially in areas with hot, humid summers. Choose disease-resistant varieties (like the new hybrids), and avoid overhead watering. A weekly spray application of 1 tablespoon baking soda to 1 gallon water helps keep powdery mildew in check when applied to the leaves and stems of the affected plant. Zinnias should be protected from browsing deer and rodents.
Maintenance: Keep zinnias evenly moist, and feed them with a well-balanced fertilizer every few weeks for best flower production. For extended bloom, deadhead plants throughout the season. Remove unsightly leaves to prevent the spread of disease and to keep plants looking good.
Propagation: It’s easy to save seed from spent blooms after the petals have faded and the remaining flower heads have dried out. Expect variability in color and form as collected seed often does not resemble the parent plant.