The rose blooms may be suffering from some type of blight. This is usually temporary but there are a number of fungicides labeled for use on roses which may be helpful, especially during rainy periods.
Your roses will benefit from being fertilized about every 6 weeks or so during the growing season. A little less often is fine if they are vigorous and blooming well. You can scratch the fertilizer into the surface inch or two with a rake and then water it in well. Water the roses as needed since sunlight, soil type, temperature, etc. all dramatically affect how often you need to water. In general terms once or twice a week should suffice when it has not rained.
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