Sue Kreutzer wrote:

I'm new to rose tending, yet the home I now own must have at least 15
separate ones, both climbing and bushes. I was here last year in the Fall
and noted they didn't seem as healthy as I thought they should be. In fact,
some of the leaves looked down right 'sick'. Are there signs I can watch
early in the season, late Spring and summer for that would indicate
problems? I'm in northern Colorado, on the eastern plains.

Sue, in addition to the other good advice you've gotten, read up on the
watering and feeding of your roses. Roses don't need huge quantities of
nitrogen, but since they like to grow continuously throughout the
growing season, you should try to water and feed them enough to do what
they're genetically programmed to do. Start with healthy growth and
good varieties for your climate, and you've gone a long way to avoiding
disease. You should have a healthy climate for growing roses up there,
if you can keep them watered and winter protected.

Fertilizers need not be expensive, but they should be complete, meaning
they should have minor nutrients in addition to NPK. One way is to use
Osmocote in the spring, since it releases nutrients through the season.
Then you can foliar feed with extra-diluted fertilizers that supply the
minor nutrients (like Growmore, fish emulsion, and liquid kelp) a
couple of times during the season.