Flowers on a pink Double Knock Out rose. (Photo by Allen Owings. Click on photo for downloadable image.)

News Release Distributed 02/22/13

By Allen Owings 
LSU AgCenter horticulturist

HAMMOND, La. – Home gardeners need to increase their knowledge and awareness of management practices recommended for roses in our landscapes.

Roses are one of our most popular ornamental plants. We have types of roses, but basic care is the same for most. 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 the best, grow the best and bloom the best in the landscape. This means eight hours or more of direct sun daily. Less than eight hours a day is not sufficient for ideal performance. Because many of us underestimate the amount of sun that our landscape receives, it’s a good idea to take some time on a sunny day and actually measure how much sunlight falls on different parts of your landscape.

Soil pH 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 – soil test. You can lower the pH with sulfur products and raise it with lime. But always do this based on the results of a soil test.

What about pruning? In south Louisiana, mid-February is the time to prune most rose varieties. They should also be pruned in early September. Do heavy pruning in February with light pruning in late summer. Hybrid tea roses need to be pruned more heavily than floribunda, grandiflora and landscape shrubs roses.

Fertilization is important. This is especially true if you don’t follow some of the other practices and care considerations carefully. To maximum spring growth and first flowering in April, roses should be fertilized in late winter to early spring. Use a slow-release fertilizer. You can also fertilize again lightly in early summer and lightly again after late-summer pruning.

Mulch roses with 2-3 inches of pine straw. You can use other mulches, but pine straw seems to do best on roses. Freshen the mulch layer as needed. Mulch suppresses weeds, minimizes soil temperature fluctuations and conserves soil moisture.

Disease and insect management are important when growing roses. Follow a preventive fungicide application program to control blackspot fungus on hybrid tea, floribunda and grandiflora roses. Usually landscape shrub roses, like the Knock Out variety, do not need fungicide applications. It is important to control blackspot in spring. If the disease gets started, it is hard to get under control later in the year. Major insects affecting roses are thrips and aphids.

All of these practices will help your roses perform successfully long-term in the landscape.

You can see more about work being done in landscape horticulture by viewing the LSU AgCenter Hammond Research Station website. Also, like us on Facebook.  You can find an abundance of landscape information for both home gardeners and industry professionals.

Rick Bogren