In article , Rodger Whitlock
writes
There are three schools of thought about when to cut down dead
perennials, the Fall-Winter school, the Winter-Spring school, and
the nihilists in the No-Cutdown school.

If you think your garden looks better in winter with all the dead
growth intact, then by all means leave it until late winter or
early spring (but not so late that the new growth is starting to
emerge -- if you leave it that late, you are a nihilist).

There is a school of thought that says that last years dead growth left
on will provide some frost protection for the crown over the winter!
--
Jane Ransom in Lancaster.
I won't respond to private emails that are on topic for urg
but if you need to email me for any other reason,
put jandg dot demon dot co dot uk where you see deadspam.com