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Rose Care
The most commonly grown roses in Louisiana include hybrid teas, floribundas, grandifloras, shrub and miniatures.
To get more information on varieties and other rose questions, contact your local county agent. In Rapides Parish, contact Terry Washington at (318) 767-3968 or twashington@agcenter.lsu.edu.
Here are some recommendations on how to keep these plants healthy and beautiful.
Planting Time
Recommended planting dates for roses are late December through early February in south Louisiana and late January through February for north Louisiana. It is important to plant bare-root roses as soon as possible after they are received. Container roses may be planted throughout the year, although summer should be avoided because of heat and possible drought stress. Ideally, transplant rose bushes in the landscape during the dormant season.
Planting Location
Sunlight and drainage are two key environmental conditions in growing roses. Select a well-drained area that receives at least six, and preferably eight to 10 hours of sunlight daily and is not too near large trees or hedges. Morning sun is especially good since it quickly dries the foilage, thus reducing disease problems. As a rule, roses grow best in full sunlight and should not be considered for shade or partial shade situations.
Planting and Bed Preparation
Raised beds are usually recommended for new rose plantings. This is especially critical if rose are to be grown in a poorly drained area. In bed preparation, heavy soils need to be amended with organic matter (pine bark, peat moss) and sharp sand. Amend light sandy soil with organic matter only. A light application of a slow-release complete garden fertilizer should be applied at planting or within two weeks thereafter. Be sure to have a soil sample analyzed before planting.
Watering
Rose require about an inch of moisture a week in spring, summer and fall. A thorough soaking is preferred instead of frequent sprinklings. In general, water thoroughly once a week, when needed. Wetting the foilage should be discouraged because it leads to increased incidence of disease.
Fertilization
Begin a fertilization program when new growth begins in the spring, and continue through late August or early September. A recommended rate is 1/4 pound of a complete fertilizer per plant in the spring and about half that amount in late spring/ early summer and again in late summer.
Mulching
A good mulch is a must for growing roses. An organic mulch retains moisture in the soil, keeps the root system cooler in the summer and warmer in the winter, prevents weed growth and improves the soil as the mulch decomposes.
Pruning
Prune roses in late winter (February) and normally again in late summer (August). Roses are pruned to: (a) remove dead wood, (b) stimulate new growth, (c) control size and shape and (d) increase air circulation which reduces the incidence of disease.
Diseases
Black spot, a fungal disease, is the most widely distributed and destructive disease of roses in Louisiana. It can be recognized by the nearly circular black spots with frayed or fringed margins. The spots vary in number on the leaf, but usually are present on the upper surface. Although the spots are unsightly, the more serious effect is from premature defoliation, which reduces plant vigor.
To control black spot, a regular, preventive fungicide spray program must be be followed throughout the growing season. This spray schedule needs to begin as soon as new leaves begin appearing after pruning in late winter. Fungicides containing captan, mancozeb, triforine, chlorothalonil, thiophanate methyl or thiophanate methyl plus mancozeb are recommended. Be sure to follow label recommendations.
Powdery mildew appears in early spring and late summer when nights are relatively cool. Symptoms include the white coating of the fungus growth which covers young buds, resulting in no bloom or distorted leaves. Leaves curl slightly or may become blistered. This disease occurs on leaves, buds and canes, causing a stunting and twisting of new growth. Fungicides with the following active ingredients are recommended for powdery mildew control: benomyl, triforine, thiophanate methyl or thiophanate methyl plus mencozeb.
Leaf rust is another rose disease prevalent in Louisiana. It is recognized in the early stage by the appearance of rough, circular, bright orange spots on the underside of leaves and on stems. Spray with a triademizone material for best control.
Crown gall is recognized by the presence of rough galls or overgrowth on the roots, crown or canes. Galls usually appear near the soil line or graft union. Infected plants become stunted. Discard infected plants.
Insects
Insects and mites attack rose flowers and foliage. The most common insect damaging rose flowers is thrips. Buds infested with thrips will not open properly, producing distorted blooms with discolored edges on the petals. Thrips control measures include applications of malathion, Orthene or Mavrik at recommended rates.
Aphids are probably the most common insect found on roses in Louisiana. These insects attack the young, growing foilage and buds, feeding on plant juices. Although a problem, aphids are easily controlled with regular applications of recommended miticide about seven days apart.
Cucumber beetles and grasshoppers are occasionally pests on roses. Apply Thiodan, Sevin or Dursban for adequate control.
Following these recommendations will go a long way toward having a beautiful rose garden.
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| Posted on: 3/31/2005 10:04:22 AM |
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