Zinnias are annual plants in the Asteraceae family that offer a wide variety of heights, colors, and types of flowers. Zinnias are very easy to grow and require little maintenance but offer bright, showy flowers. They attract butterflies and make excellent cut flowers.
Plant heights range from 6 inches to several feet tall. Zinnias can be grown in zones 1 through 10. They prefer well-drained, fertile soil and should be grown in full sun.
How to Grow
Sow zinnia seeds directly into the soil, after the last frost. Cover with ¼ soil and keep soil moist until the seeds germinate, in about 4 to 7 days. Plant in soil that is well-drained but fertile and is located in full sun. Consider adding compost to loosen and fertilize soil and to help retain moisture.
Especially in humid areas, zinnias need air to circulate around the base of the plant, so thin seedlings to about 6 to 8 inches apart for shorter varieties and 12-18 inches apart for taller varieties. This can be done when the seedlings are about 3 inches tall. Keep seedlings fairly well watered until they are more mature.
Pinch or cut of dead flowers (generally at the base of the next closest leaf branch, being careful not to damage any leaves or buds) to encourage bushier growth and more flowers.
Zinnias will reseed themselves, but if you’d like to save the seeds to use next year, simply leave some flowers on the stalk until they appear dry and brown. Cut off the flowers and flake out the seeds into a bag. Generally, the seeds are attached to the base of the petals in zinnias.
In the humid southeast, zinnias are susceptible to powdery mildew, which begins to show up in late summer. If this is a problem where you live, there are some mildew-resistant varieties to try instead of the traditional seeds. Additionally, water plants at the ground instead of spraying from above to reduce mildew problems.
Powdery mildew-resistant varieties include
- Zinnia angustifolia
- Zinnia haageana
- Blue Point series
- Pinwheel zinnias
- Profusion zinnias
- Zahara zinnias
Try searching for “mildew resistant zinnias” to find other mildew-resistant varieties.