Pruning knockout roses
This spring I planted a grouping of knockout roses in front. Ideally, I want to keep them at about 3' tall with a nice soft rounded/ovalish shape, which I see frequently in other landscaping. 4' would be okay, especially when the other shrubs get bigger.
I have heard you aren't supposed to prune them the first year, but they are getting quite tall and spindly this year and have outgrown all the other stuff already.
Are roses like fruit trees, where if I summer prune they'll stay smaller and bushier? Or should I just let them go this year and prune them back harshly this winter?