Marigolds And Zinnias Good For Late Summer And Fall Says LSU AgCenter Horticulturist

Allen D. Owings  |  7/29/2005 9:19:41 PM

Consider marigolds and zinnias for late-summer and fall bedding plants. This swizzle cherry and ivory zinnia has done well in LSU AgCenter trials.

News You Can Use For August 2005

We usually associate warm-season bedding plants with the spring and summer growing seasons. Many of these plants, however, actually do better from mid- and late summer through the fall, according to LSU AgCenter horticulturist Dr. Allen Owings.

This phenomenon is especially true in the lower portions of USDA hardiness zone 8 and throughout zone 9. Zinnias and marigolds are two excellent examples of warm-season bedding plants to try from August through the first killing frost.

"Marigolds are a great fall blooming plant," Owings says, adding, "They produce bold colors and striking flowers and are great for fall landscape displays."

The horticulturist notes that Texas A&M University began recommending marigolds for the fall as a replacement for garden mums about 10-15 years ago, and this is now beginning to catch on with landscapers and home gardeners.

Many marigold plantings in the late summer and fall will actually outperform a spring planting in terms of "lasting in the landscape." Most spring-planted marigolds usually decline considerably in south Louisiana by June because of petal blight, stem lodging (African cultivars) and spider mites. An August planting typically does not experience the flower disease because of the drier fall weather. Also, there are fewer spider mite problems this time of the year.

Marigolds come in a wide range of varieties. African marigolds are taller, larger, cut-flower type of varieties. Primary colors are orange, gold and yellow. Examples include the Inca II, Perfection and Antigua series.

French marigolds are the shorter, smaller-flowered types and include the Hero, Bolero, Bonanza, Janie, Durango and other series. More color variation is available in the French varieties. There are also hybrid marigolds.

Zinnias have a few disease problems – primarily leaf spots (caused by fungus and bacteria), flower/petal blight and powdery mildew. Like marigolds, these problems can be greatly reduced, and plant performance can be improved in a late summer and fall planting compared to a spring planting.

Many zinnia species are available. Traditional, older zinnia varieties are the Zinnia elegans varieties. Some of these varieties are good for cut flowers, like the Benary Giant series.

Other varieties are better as short bedding plants, such as the Dreamland series. A wide range of flower colors is available in these zinnias. The new Swizzle series of zinnias have performed well in LSU AgCenter trials. The Magellan series shows promise, too. The new Zowie! Yellow Flame zinnia is an All-America Selection for 2006.

Other popular zinnia groups are the narrowleaf zinnias (Zinnia linearis or Zinnia angustifolia) that include the Crystal and Star series. Flower colors available in these are gold, orange and white.

The newest zinnia group is a cross between the narrowleaf zinnias and the older zinnia varieties. These are hybrids and include the Profusion series. Available flower colors are white, orange, cherry, fire and apricot. Some of these are AAS winners.

"Zinnias and marigolds need less care and provide great satisfaction in the landscape as the long hot days of summer fade to cooler shorter days of fall," Owings says, adding, "Remember that bed preparation is important, as it is for all bedding plants."

The horticulturist also says to remove old flowers as they fade, because this will help extend the season significantly. A couple fungicide applications during the course of the season will also slow petal blight and foliage diseases.

For related topics, click on the Lawn and Garden link at the LSU AgCenter Web site, www.lsuagcenter.com. Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.

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On the Internet: LSU AgCenter: www.lsuagcenter.com/

On the Internet: www.louisianalawnandgarden.org

Source: Allen D. Owings (225) 578-2222, or aowings@agcenter.lsu.edu

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