Two years ago, we planted 6 beautiful knockout rose bushes. They boom beautifully in June, then stop. We have tried everything: different fertilizers, no fertilizers, pruning, not pruning. However, we cannot get them to continually bloom. What are we doing wrong?
Roses need regular feeding with a high phosphorus food like Jack’s Blossom Booster. Regular removal of spent flowers is also required. It sounds like you’re doing all this. The only other thing that can prevent re-blooming is insufficient direct sun…there is no compromise. They need a MINIMUM of 8-9 hours of direct sun during summer and more is better…they can’t get too much sun. The fact that the bloom well early leads me to believe that they are getting too much shade one the leave emerge on the trees. You’ll need to find and even sunnier place for them or remove whatever is shading them.