You prune in spring. Cut them back to about 1 ft or so from the crown at the base of the plant. Cut in a fan shape. See any good gardening book or search online for how to make the actual cuts when cutting the rose branches.
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With spring right around the corner, here is a tip for pruning rosebushes. Get a medium cardboard box, then use a spring loaded clothespin to grab each branch just above where you make your cut. Leave the thorny branch in the clothespin jaws and transfer it into the box. This sure saves your hands from being jabbed by all those thorns!
By Sandy from Pittsburgh
RE: Pruning Rosebushes
This ought to work. Just be sure and prune 1/4 inch above a bud. Canes can be pruned most anytime except fall when you might initiate new growth that would be frozen back. (01/29/2005)
I don't usually worry about pruning my rose bushes. The deer that like to call my yard their home enjoy doing this for me. I just have a little cleaning up to do later. I do like the idea of the clothespins, though. I have been using thick gardening gloves and that works too. (02/06/2005)