Sustainable Landscape News Distributed 02/11/10

By LSU AgCenter Horticulturists Dan Gill, Allen Owings and John Young

Growing roses in Louisiana is a challenge for home gardeners. A major problem in the enjoyment of landscape roses is disease – primarily blackspot and powdery mildew – brought on by our environmental conditions. Heat and humidity have an adverse affect on many rose varieties that we grow in Louisiana.

The enhanced popularity of landscape shrub roses has stimulated new interest in roses over the past few years. Traditionally, modern roses – such as hybrid tea, floribunda and grandiflora varieties – have dominated the market.

Landscape shrub roses in the modern rose category were a small percentage of the modern rose market in the 1990s, but that trend is now totally reversed. It’s been driven, in large degree, by the tremendous success and popularity of the Knock Out variety roses. Landscape shrub roses, also called landscape roses or shrub roses, require minimum pruning, decreased irrigation and fertilization, and less disease management than other rose categories.

Knock Out was an All-America Rose Selections winner in 2000. It took a couple years for Knock Out to be on the market for most horticulturists to realize how great a plant it is. Knock Out is advertised to grow to a mature height of 4-5 feet with a spread of 4-5 feet. If left unpruned, these plants easily can reach sizes of 8 feet tall.

Blooms are deep, fluorescent, cherry red complimented by glossy, burgundy-green foliage. In addition to the original Knock Out rose, varieties now include Knock Out Pink, Blushing Knock Out, Rainbow Knock Out, Double Knock Out, Pink Double Knock Out and Sunny Knock Out.

Another group of roses receiving attention now are the EarthKind roses being promoted by Texas A&M University. The original 11 EarthKind roses were Belinda’s Dream, Caldwell Pink, Carefree Beauty (Katy Road Pink), Climbing Pinkie, Else Poulsen, Knock Out, Marie Daly, Mutabilis, Perle d’Or, Sea Foam, and The Fairy. In the past few years, the EarthKind list has grown to include Spice, Duchesse de Brabant, Ducher, Georgetown Tea, Madame Antoine Mari, New Dawn, LaMarne and Souvenir de St. Anne’s.

The LSU AgCenter has EarthKind roses under evaluation in several locations.

Some hybrid tea roses also require less maintenance and are less susceptible to blackspot than others. These include Gemini, Elle, Valencia, Mister Lincoln, Tiffany, Veterans Honor, Olympiad, Tahitian Sunset, Midas Touch, St. Patrick and Moonstone.

Floribunda roses that are recommended for low maintenance include Cinco de Mayo, Julia Child, Easy Going, Hot Cocoa, Livin’ Easy and Moondance.

Landscape shrub roses to try, besides the Knock Out varieties, include Home Run, Carefree Celebration and Lady Elsie May.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.louisianahouse.org and www.lsuagcenter.com/lyn.