Richard Bogren, Owings, Allen D. | 1/4/2011 1:13:59 AM
Roses are one of our most popular ornamental plants, and home gardeners need to learn more about how to care for them, according to a horticulturist with the LSU AgCenter.
“We have many types of roses, but basic care is the same for most,” says Allen Owings. “Keys to success with roses include: correct sunlight conditions, ideal soil pH, proper pruning, regular fertilization, proper mulching, disease management and insect control.”
Roses need full sun in order to perform best, grow best and bloom best in the landscape, Owings says.
“This means eight hours or more of direct sun daily,” he says. “Less sunlight is not sufficient for ideal performance. Many of us underestimate the amount of sun that our landscape receives.”
Soil pH – or acidity – also is important for roses. Ideally, soil pH should be in the 6.5 range. This is considered slightly acid.
“Do not guess on soil pH,” Owings says. “Test your soil. You can lower the pH with sulfur products and raise pH with lime products, but always do this based on the results of a soil sample.”
Owings says mid-February is the time to prune most rose varieties in south Louisiana. They also should be pruned in early September.
“Heavy pruning is done in February, with light pruning in late summer,” he says. “Hybrid tea roses need to be pruned more heavily than floribunda, grandiflora and shrub roses.”
The LSU AgCenter horticulturist says fertilization is very important, especially if some other cultural practices and care considerations are not being followed.
To maximize spring growth and first flowering in April, roses should be fertilized in late winter to early spring with a slow-release fertilizer. You also can fertilize again lightly in early summer and again after late-summer pruning.
Owings suggests mulching roses with 2-3 inches of pine straw.
“You can use other mulches, but pine straw seems to do best on roses,” he says. “Refresh the mulch layer as needed. Mulch suppresses weeds, minimizes soil temperature fluctuations and conserves soil moisture.”
Owings stresses the importance of disease and insect management and suggests a preventive fungicide application program to control blackspot fungus on hybrid tea, floribunda and grandiflora roses.
“It is important to control blackspot in the spring,” he says. “If the disease gets started, it is very hard to get under control later in the year.”
“Usually, landscape shrub roses, like the Knock Out variety, do not need fungicide,” he adds.
He also suggests being on the lookout for thrips and aphids – major insects affecting roses – and treating them as they appear.
“All of these practices will help your roses be successful in the landscape for the long term,” Owings says.