If you live in a Northern region, you will probably need to protect your roses during winter. No matter which method you use, wait until the soil has frozen: You want to keep the plants frozen all winter, not protect them from the cold. Here are common methods:
Mulch. Cover rose canes with several inches of loose mulch, such as weed-free straw, pine needles, or wood chips.
Rose cones. Protect roses with cones -- foam devices that look like white traffic cones. Mound soil over the rose crown, then cover the entire plant with the cone. Cut a few ventilation holes in the cone, and anchor it so it won't blow away during winter windstorms.
Even with good conditions, roses need a little maintenance. Here are treatments for common diseases:
Black spot. This disease looks like it sounds -- unsightly spots on the foliage. Prevent this disease with a garden fungicide labeled for use on roses during periods of cool, wet weather. Don't plant your roses too closely together and make sure they're in full sun. Avoid watering with a sprinkler -- wet foliage encourages disease.
Learn more about stopping black spot.
Powdery mildew. If you see a gray or white, fuzzy-looking film on your rose leaves, it's probably powdery mildew. Prevent it by using a garden fungicide labeled for use on roses during periods of wet or especially humid weather. Encourage good air flow and make sure your roses get plenty of sun.
Japanese beetles. These big bugs can practically eat all the foliage and flowers from a rose plant in just a couple of days. Pick light infestations by hand and drop the beetles into soapy water. Spray severe infestations with a garden insecticide containing carbaryl, permethrin, or neem.
Learn more about stopping Japanese beetles.
Aphids. If you see masses of tiny insects on your roses, it's likely aphids. If infestations are light, spray them off plants with a strong stream of water from a garden hose. For larger infestations, use a garden insecticide containing carbaryl, permethrin, or neem.
Learn more about stopping aphids.
Test Garden Tip: Select roses suited to your region; they'll be the best at standing up to disease. Also look for varieties labeled as disease-resistant -- but keep in mind that disease-resistant doesn't mean disease-proof.
The American Rose Society (ars.org) is a fantastic resource for more information about growing roses.