Roses

Roses grow in virtually every shape, size and color. They are divided into three classes: species roses (wild roses from which all others were bred); multifloras which bloom just once each season with a single row of five to twelve petals on each flower, are known for fragrance and generally low maintenance with a large variety of sizes, including Antique (Old Garden) roses; and modern roses including hybrid tea, Grandiflora, Floribundas, Polyantha, shrub, climbing roses, miniature roses and tree roses.

Rose hardiness is identified in rose catalogs and at local nurseries, making it easy to choose rose varieties that are appropriate for your area. Grafted roses are graded by the number of canes growing from the bud union. With three canes present, number 1 is the highest. Look for fresh, unwrinkled canes on a plant with a well-developed root system. Canes should be 15 to 18 inches long and pruned. A cane thinner than a pencil should be removed before planting.

Roses require eight hours of morning sun or six hours of afternoon sun. They grow best in well-balanced soil rich in organic matter with good drainage, and prefer slightly acidic soil with a pH of 5.5 to 7. Rose roots will rot in wet soil, but plants need an inch of water each week. Roses are heavy feeders that should be fed after their spring pruning, a second time after the first bloom cycle in late June and finally in early to mid-August, two months before the first frost. Always water prior to applying fertilizer. Fertilize around the drip line of the rose away from the bud union. A balanced fertilizer of 10-10-10 is good for roses. Organic fertilizers release nutrients slowly and cannot burn the plant. Excessive applications of chemical fertilizers may damage the plant.

Most roses require winter protection. If there is no snow cover, the rose bush will suffer. Cover the plants with pine boughs or mounded soil, mulch, compost or seaweed over the lower stems. Don’t mulch with leaves or anything that creates a cozy habitat for voles – they may girdle and kill the roses. Trim or tie down any unruly canes. No other pruning is required in the fall. In the spring pull the protective mound away from the base of the bush.

Know the size, shape and habits of your rose plant before selecting a site for planting. Dig a hole at least twice as wide and deep as the pot. Mix peat moss, manure and soil to fill hole. Plant two feet apart. Container roses can be planted in early or late spring and in late summer or fall. If you purchase a rose plant with roots that are intertwined, separate them gently. If they cannot be unwound, cut the matted roots on the bottom. Fill half of the planting hole with soil mixture and pack down firmly. Set the root ball into the hole so that the crown or bud union is about 1-2” below ground level. Finish filling the hole. Make a saucer around the plant and water slowly and deeply. Place 2-4 inches of mulch near but not touching the stem to reduce weeds, moderate temperatures and conserve moisture. Bare root plants are planted the same way, but soak the roots in water for 1-2 hours before planting, then spread them over a firm mound in the center of the hole. Roses are best transplanted when dormant.

The three biggest rose problems in New England are Japanese beetles, blackspot and powdery mildew. Minimize problems by growing disease-resistant varieties and using good gardening practices–providing enough sunlight, free air circulation around bushes and regularly removing all diseased material from the shrub and the surrounding area.

Japanese beetles can be a problem in July and August. They can be picked off and dropped into soapy water. The beetles hatch from grubs in your lawn and must be treated there. Japanese beetle lures will bring more beetles into your yard than they capture. Other insects that affect roses include aphids, cane borers, midge, thrips, and spider mites.

Blackspot is a fungus characterized by dark spots, round and varying in size, on the leaves. The leaves will turn yellow and fall off. Remove all infected leaves from the area and discard in the trash. Blackspot is a product of warm, humid, rainy conditions. Spray with a fungicide and avoid overhead watering.

Powdery mildew is the most prevalent and serious diseases of roses. The leaves fold at mid-rib or are distorted, white or gray powdery material appears on new buds and leaves. Powdery mildew attacks the plant from the top down appearing when warm days and high humidity combine with cool nights. Prune and remove infected plant material followed by application of fungicide. Good air circulation and plentiful sunlight will help prevent powdery mildew. Other cultural problems include downy mildew, rust, botyritis, rose mosaic virus, rose cankers and crown gall.

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