Mexican zinnia, or spreading zinnia, is a charming choice when you want the bright color of zinnias but don't want disappointing losses from powdery mildew that often strikes hybrid garden zinnias. It is native to the southeastern United States and, as you might guess, Mexico, and thrives in hot weather.
Description of Mexican zinnia: Mexican zinnia can grow upright to 24 inches high and bears golden, orange, or red flowers that cover the plant all season and look a little like marigolds. Some varieties, such as 'Persian Carpet' and 'Orange Star,' grow more prostrate to about 8 inches high. All members of this species are untroubled by powdery mildew.
How to grow Mexican zinnia: Plant in well-drained soil of moderate fertility in full sun. Mexican zinnias also thrive in containers filled with enriched, peat-based potting mix. Plant seedlings 8 to 12 inches apart after the final spring frost.
Propagating Mexican zinnia: By seed. You can sow Mexican zinnia seeds directly into the soil. However, for earlier bloom, sow seeds in peat pots indoors 8 to 10 weeks prior to planting out. Seeds germinate in 5 to 7 days at 70 to 75 degrees Fahrenheit.
Uses for Mexican zinnia: Use Mexican zinnias in sun-drenched pots or in the front of an annual or mixed flower garden. They are wonderful for cutting and drying and therefore deserve a place in the cut flower garden.
Mexican zinnia related varieties: 'Star Gold' has golden flowers. 'Crystal White,' an award winner, has white flowers. 'Golden Orange' has golden orange florets with a lighter lemon stripe. Dwarf 'Persian Carpet' has multicolored double flowers.
Scientific name for Mexican zinnia: Zinnia haageana (syn. Z. angustifolia)