I have been growing Knockout roses with good success. The are hybrids, developed for hardiness so that even a bumbling gardener like me can’t harm them.
Last year someone gave me a fancy rose bush — I think it is called a Tiffany. It produced beautiful roses, but only about 2 of them. This year, the leaves are turning yellow, and the plant looks sick.
In the beginning of the season, I pruned it, and mixed organic rose food into the soil. I think the pruning was fine, I just don’t know what the problem is and have no clue what to do about it.