Question
Knockout roses: i pruned them after the 1st. frost in the fall is that alright?/rose of sharon: newly planted last fall. should i cut branches to the ground?

Answer
When you prune depends on where you garden. If your winters are not very cold, then pruning in the fall is fine. If your winters are very cold,  spring is  better time.
I answer questions on roses but I do have a Rose of Sharon and prune it every year in late winter or very early spring. Some gardeners cut their shrubs back very hard - to 3 or 4 buds per shoot -- to control overall size and encourage larger blooms. Others simply let their shrubs grow into their natural shape. This latter approach encourages more, smaller blossoms. The plant blooms on the new wood of the current season so summer trimming means that you'll lose out on flowers. I think that you should prune it down to the ground for his year only and that will encourage sturdy new growth but I wouldn't do it every year.