Because roses are rather finicky about soil, it's a good idea to have your soil tested. Some large nurseries and most university extension services will do this for a nominal charge. Once the soil analysis is complete, you will know exactly what should be added to the soil and in what amount. This is not the time for skimping. Any extra effort you put into advance preparation will pay off in superior results for years to come.
Standard care includes watering, fertilizing, protecting against pests and diseases, and pruning.
Roses need regular applications of water for top production of flowers. It makes no difference whether the water comes from a hose or from rain. Just make sure the roses receive enough water to moisten the soil to a depth of 18 inches every week during the growing season. The easiest way to check this is with a long screwdriver or stiff piece of wire, such as a straightened-out coat hanger. Either device will be easy to push through moist soil, more difficult once it hits dry soil.