Question
Hi
I just noticed that my three knockout rose bushes leaves are curling.  I bought them last summer and they were beautiful.  Now the leaves are curling--what would cause that?

Answer
Rose leaves curl for many reasons. Sometimes it is caused by chilli thrips, but that depends where you garden if you have these insects. When conditions are right, roses get powdery mildew and when it starts, it causes the leaves to curl up along the edges. A virus can also cause the leaves to curl up. When the weather suddenly turn hotter rose leaves will curl. It is hard to diagnose without actually seeing the rose leaves. Hope this helps.