I am pretty awful at growing roses, but I've joined a few groups and forums and put my learning cap on. However I only have Knock Out roses at this time. Mine are three years old and I've never pruned them - which means they are a huge, heavy, mess and are so big they tend to lay on the ground around the edges. Think of a huge mushroom cap sitting on the ground! I'd like to prune them to open up the interior and remove crossing stems, but also to remove a lot of the growth in the lower 1/3 of the plants, creating a mini tree effect. When is the proper time to prune Knock Outs? I live in z6 of the Appalachian Mountains of Virginia. Thanks!