Pink and red forms of Double Knock Out roses provide abundant blooms spring through fall. (Photo by Allen Owings) Roses should be pruned not only in February but also later in the year. (Photo by Mark Claesgens)
News Release Distributed 02/13/15
By Allen Owings
LSU AgCenter horticulturist
HAMMOND, La. – Roses continue to be popular in our residential landscapes, so home gardeners would be well served to increase their knowledge and awareness of recommended management practices for roses. Proper care at the proper time goes a long way to enjoying landscape success.
We have many types of roses, but basic care is the same for most. Keys to success include proper variety selection, correct sunlight conditions, ideal soil acidity or pH, proper pruning, regular fertilization, proper mulching, disease management and insect control.
Start with selecting a variety that will appeal to your rose goal.
If you want roses for cut flowers, a hybrid tea or a grandiflora rose may be best for you. Floribunda and landscape shrub roses bloom abundantly but make poor cut flowers, although they require much lower maintenance. Ground cover roses fit a smaller space in the landscape and will not dominate and tower over other plants in companion gardens. Old garden – antique – roses continue to be popular in Louisiana.
Roses need full sun in order to perform their best, grow their best and bloom their best. 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 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 acidity or pH is important for roses. Ideally, soil pH should be around 6.5. 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 Louisiana, February is the time to prune most rose varieties. Prune in early February in south Louisiana, mid-February in central Louisiana and late February in north Louisiana. Also prune roses in late August to early September. Do major pruning in February with light pruning in late summer.
Hybrid tea roses need to be pruned more heavily than floribunda, grandiflora and landscape shrub roses. Older garden roses generally just need shaping and pruning to direct and control the growth habit.
Fertilization is important. This is especially true if you’re less careful about following some of the other practices and care considerations. To maximize 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. You can freshen the mulch layer by adding new mulch 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 visiting 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 at both sites.
Rick Bogren