What is wrong with your knockout roses if the petals of the rose are curling under and they looked pointed?
It could be a heat stress issue and the rosebushes cannot get enough water into the petals fast enough to deal with the heat. It can also be an insect laying eggs in the petals and stinging the petals with a substance that makes them curl to help protect the eggs. Open some of the curled petals up and see if there are any little bugs or eggs in there. If there are, then a systemic insecticide that moves up through the root system and into the natural juices of the rosebushes may be in order.