Answer: In my experience it is better to wait until spring as a general rule for woody shrubs. Anything that blooms on new growth can be trimmed in late winter to early spring, removing any winter damage and thinning if appropriate. Those that bloom on old growth are generally not pruned until right after they bloom to avoid removing flowering wood.
With perennials, wait until after several frosts or a hard freeze. Then trim back any frost killed stems and foliage. In spring, you will probably need to go through and tidy up any that have a perennial rosette of foliage and have become shabby over the winter.
I hope this helps.
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