In article , michael adams
writes

The only real danger might be pruning stuff in the wrong way so
you lose next years flowers etc. So I'd suggest you first try and
identify any plants that you're tempted to cut back.

But if you really have to cut back, then just after flowering is a
reasonable rule of thumb.

If you prune at the wrong time, you won't kill the plant - you'll merely
lose next years flowers (and have to wait two years before you can
identify it ;-) )

The only caveat is - if you want to cut something back drastically, say
to less than half its original size, it's probably best to do it over
two years - cut half the branches right back this year, then (providing
the bush isn't sulking too much) cut the other half next year.
--
Kay
"Do not insult the crocodile until you have crossed the river"