Beginner Gardening: How do I overwinter Salvia nemorosa \'Caradonna\' with purple spikes?, 1 by Orange349

Orange349 wrote:
I am very new to this. I have a couple of large plants of Salvia nemorosa \'Caradonna\' in flowerbeds.

They flowered well. I didn\'t deadhead them during the summer (I now realise I should have). One plant I cut the dead stalks off, the other one I left them, as they actually look better on.

How should I overwinter them?
I have found conflicting stuff online. One site said to leave them completely as-is, as the plant matter protects from frost, then cut them back heavily in spring. Another site said cut back by a third, ready for cutting back heavily in spring.

The first photo shows the plant still with stalks on. I can see they are sprouting new green leaves at the bottom, illustrated by the second photo.

Any advice would be very much appreciated.