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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Summer Care of Roses

This article was published originally on 6/17/2009

Roses are one of the most beautiful plants in the home landscape. While roses are attractive, they do require good care. Important cultural practices during the summer months include watering, fertilizing, deadheading, and pest control. Watering Modern roses, such as hybrid teas, floribundas, and grandifloras, require watering during hot, dry weather. The frequency depends upon weather conditions and soil type. In most gardens, a deep soaking every 7 to 10 days should be sufficient. Soak the soil to a depth of 10 to 12 inches. If possible, apply the water directly to the soil around each plant. Overhead watering wets the foliage and increases disease problems. If overhead watering is unavoidable, morning is the best time to water roses. Morning applications allow the foliage to dry quickly. An excellent way to conserve soil moisture is by mulching. Suitable mulches include wood chips, shredded bark, pine needles, and cocoa bean hulls. Spread 2 to 4 inches of mulch around the base of each plant or over the entire bed. Mulches also help to control weeds.Fertilizing To encourage vigorous growth and abundant bloom, hybrid tea, floribunda, and grandiflora roses should be fertilized three times a year. The first application should be made in early spring immediately after pruning. Apply the second fertilizer application during the first bloom period. The third application should be made in mid to late July. Do not fertilize after July 31. Later fertilization will produce succulent new growth which may not harden sufficiently before winter. An all-purpose garden fertilizer, such as 10-10-10, should produce excellent results. Sprinkle 1/4 cup of fertilizer around each plant per application. Deadheading Deadheading or the removal of faded flowers is done to encourage additional flower production on hybrid tea and other repeat-blooming roses. The deadheading procedure is slightly different for newly planted and established roses. During the first growing season, it's usually recommended that the spent flower be removed above the uppermost 3-leaflet leaf. Removal of a larger percentage of the rose's foliage reduces the plant's ability to manufacture food and slows growth. When deadheading established roses, the stem may be cut back to a 5-leaflet leaf. Retain at least two 5-leaflet leaves on each shoot. Use sharp tools (hand shears or knife) to remove faded flowers. Cut about 1/4 inch above an outward facing bud and leaf with the cut made parallel to the angle of the leaf. Controlling Insects and Diseases Continue a rigorous spray program through the summer months to control insect and disease pests. Combination sprays, which include an insecticide and fungicide, are available in garden centers and nurseries. Disease problems are most severe during periods of rainy weather. Begin applying fungicides at the first sign of disease symptoms. Apply fungicides to both the upper and lower leaf surfaces. Regular applications are often necessary to control black spot and other diseases. While roses require considerable care, the results can be strikingly beautiful.