GARDEN CAPSULE
JAN RIGGENBACH
The challenge: Your zinnias are flowering beautifully, but their foliage is covered with spots and gradually dying.
The solution: To prevent leaf spot diseases, plant zinnias in full sun. Plant large varieties 18 inches apart and smaller varieties a foot apart to allow enough space for good air circulation. Water the zinnia patch in dry weather but avoid getting the foliage wet with overhead sprinkling. Clean up all zinnia plant debris in the fall, and don’t plant zinnias in the same space more than once every three years. Consider planting Zahara zinnias, disease-resistant varieties that grow 12 to 18 inches tall and are covered with flowers 2½ inches in diameter.
Pluses: The same cultural practices that help control leaf spots also help keep in check another common fungal disease, powdery mildew. Growing zinnias from seed is easy, quick, and relatively inexpensive; planting more seeds in midsummer offers a second chance at success.
Minuses: Although leaf-spot diseases in zinnias can be prevented, once the foliage is marred, it can’t be restored. The tall, large-flowered zinnias with long stems that are favorites for bouquets are susceptible to all the common fungal and bacterial leaf-spot diseases.
Sources: For more information on growing zinnias, see http://hort.uwex.edu/articles/zinnias/. You can buy Zahara zinnias in spring at many garden centers, or order seeds in that series from J.W. Jung Seed Co. (800 247-5864,
www.jungseed.com) or Park Seed (800 845-3369, www.ParkSeed.com). - Jan Riggenbach