By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings
Home gardeners need to increase their knowledge and awareness of cultural practices recommended for roses in our landscapes. February and March is the best time of the year to get started with your rose garden maintenance.
Roses are one of our most popular ornamental plants. There are many 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.
When selecting a planting site, consider sunlight conditions. Roses need full sun in order to perform best, grow best and bloom best in the landscape. This means eight hours or more of direct sun daily.
Less than eight hours of sunlight each day is not sufficient for ideal performance. Many of us underestimate the amount of sun our landscapes receive.
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. Lower pH with sulfur products and raise pH with lime products, but always do this based on the results of a soil sample.
What about pruning? In south Louisiana, mid-February is the time to prune most rose varieties.
We normally associate the first pruning of the year with Valentine’s Day. Roses also need to be pruned in early September. Heavy pruning is done in February, with light pruning in late summer.
Hybrid tea roses need to be pruned heavier than floribunda, grandiflora and landscape shrub roses. If you have not completed rose pruning, get it done now – definitely by early March.
Fertilization is very important. This is especially true if some of your other management practices and care considerations are not being followed. For 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 again after late-summer pruning. Fertilize existing roses a week or two after pruning – normally in late February. Use a slow-release fertilizer.
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 is important when growing roses. Follow a preventive fungicide application program to control blackspot fungus on hybrid tea, floribunda and grandiflora roses.
Landscape shrub roses, like the Knock Out variety, usually do not need fungicide applications. It is important to control blackspot in the spring.
If the disease gets started, it is very hard to get under control later in the year. Major insects affecting roses are thrips and aphids.
Roses are not difficult to grow – if proper cultural practices are followed, they can be enjoyed with success throughout all the warm months in Louisiana.