Durable annual handles Missouri summers.



Linda Geist
  • Zinnias.By Flickr user Liz West/CC BY-SA 2.0
    Zinnias.By Flickr user Liz West/CC BY-SA 2.0
Your Show-Me Garden: MU Extension brings you gardening tips from experts around the state.

COLUMBIA, Mo. – In the search for a colorful annual flower that can handle the rigors of a typical Missouri summer, zinnia ranks high on the list, said University of Missouri Extension horticulturist David Trinklein.

“Zinnias are great flowers for Missouri gardens for several reasons,” said Trinklein. “They adore heat—which is a real plus for a garden plant in the Show-Me State. Additionally, they are very versatile, serving equally well in beds or borders, depending upon the variety chosen.”

Early Spanish explorers who happened upon zinnia in Mexico named it “mal de ojos,” which means “sickness of the eye.” Today, thanks to the work of plant breeders, zinnia is one of the most attractive, widely planted flowering annuals in the United States.

Zinnia flowers come in two forms: dahlia and cactus. Dahlia-flowered zinnias have ray florets (petals) that are broad, tightly-packed and extend somewhat downward at their tip. Cactus-flowered zinnias have quill-like petals that turn downward.

Taller varieties make excellent cut flowers. Finally, and importantly, zinnias are not difficult to grow.

Zinnia is one of the few garden flowers that can be started equally well by planting seeds directly in the garden or by purchasing transplants. If direct seeding, wait until the soil warms in the spring.

Like most flowering annuals, zinnias prefer a well-drained garden loam of moderate fertility. Space according to variety. Though vigorous by nature, they are subject to attack by several pests. Spider mites and chewing insects such as grasshopper and bud worms can be troublesome.

Powdery mildew is by far the most frequently encountered disease of zinnia, Trinklein said. Plant breeders have made good progress in developing varieties that are able to tolerate mildew better. Gardeners can help by keeping foliage as dry as possible. Avoid overhead irrigation and space plants to promote good air circulation. Fungicides labeled for powdery mildew control also can be used as a preventive measure.

For those wishing to try some of the newer varieties, Trinklein says the “Magellan” series comes highly recommended. It boasts vigorous and uniform plants that mature to a height of 12-14 inches. Its large, fully double flowers are vibrant in color and of exceptional quality, he said.

Other new zinnias of note include the “Profusion” series and the “Zahara” series. Both bear abundant flowers 2-3 inches in diameter and are available in a variety of colors. Plants grow 12-18 inches high and are extremely disease-resistant.

Both series feature varieties that have earned a coveted All American Selection award. They include “Profusion” Orange, White, Red, Double Hot Cherry and Double Deep Salmon, as well as “Zahara” Starlight Rose, Double Fire and Double Cherry.

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