Virginia is a coastal state that receives an average rainfall of 50 inches a year. Because of this, growing healthy roses in Virginia can be quite a challenge. As in any climate where rainfall is heavy, rose growers in Virginia may have to battle black spot sometime in the life of their plants. Other challenges include growing roses in saline soil along the tidewater region and growing roses in the piedmont of the western part of the state. The key to growing roses in Virginia is to get them off to the right start and then follow a regimen of regular maintenance.
Test your soil in the fall before you plant roses. A soil test can tell you what minerals are present in the soil, including salt, phosphorous, potassium and nitrogen, as well as the pH of soil. A soil test will help you to determine what amendments should be added to your soil when you plant your roses. The Virginia Cooperative Extension maintains a soil testing laboratory that will test your soil for a fee. Details on how to collect soil samples, as well as fees and instructions for sending your sample into the cooperative Extension soil lab, may be found at http://pubs.ext.vt.edu/452/452-881/452-881.html.
Prepare your planting bed for roses in spring, three weeks before planting the rose canes. Use a rototiller to break up your soil to a depth of 8 inches. Then spread organic amendments such as peat moss over the soil. Peat moss is high in acid content, which roses love. This is also the time to work in amendments based on the instructions given to you in the soil test. Roses are heavy feeders that hate wet feet, so you should increase drainage in the heavy clay soils of the piedmont region by incorporating gypsum and sand as well as a balanced (10-10-10) fertilizer. Soils in tidewater regions can also benefit from the addition of organic matter such as peat moss, manure and compost.
Select rose varieties that are hardy to your area. Virginia falls primarily within USDA hardiness zones 5 and 6, with small mountainous locations that experience temperatures consistent with zone 4 and a pocket of coastal region in the southeastern corner of the state that is in zone 7. The majority of the state experiences average low temperatures between 0 and -10 degrees F.
Dig planting holes that are at least 15 inches deep and 18 inches wide. Space them according to the directions for individual roses. Climbers should be spaced 30 feet apart, but floribundas should be spaced no more than 30 inches apart. Mix 3 oz. superphosphate and 3 shovelfuls of compost into the soil that you have removed from the planting hole. Mound up soil in the center of the planting hole.
Set the rose plant on the mound in the center of the hole, and spread the roots over the mound. The graft union of the plant should be just above ground level. Cover the roots with the soil and nutrient mix. Water with a garden hose until the soil is as wet as a wrung-out sponge. Then mound an additional 4 to 6 inches of soil around the canes to protect them while the roots establish themselves. Remove this soil as new shoots develop and the danger of frost passes.
Water roses with 1 inch of water weekly during drought periods. Apply a 2-inch layer of mulch to hold in water and prevent evaporation.
Monitor your roses and prune away any vegetation that exhibits signs of disease, including black spot. Treat roses with a regular battery of fungicides and pesticides to keep disease away. For a natural fungicide, spray roses with neem oil. Rotate this spray on a regular basis with one made from 1 tbsp. of baking soda mixed with 1 tbsp. of agricultural oil in a gallon of water.