Yes, I'm cleaning up around perennials to remove hiding places for slugs.

Herbaceous perennials can be cut back at any time after the end of the growing season if you find their appearance objectionable or if you want to just tidy up the garden for winter and remove potential hiding places for slug or snails. Contrary to common belief, leaving foliage intact does not offer any protection to the plant itself -- if that's your intent, use a mulch instead.

Of your list, there are only a just a couple of plants that could be considered to offer winter interest - the carex, euphorbia, heuchera and bergenia. These, plus the ajuga, hold foliage throughout winter so are visually more interesting than those perennials that die back fully. Even these can look a little ratty after a tough spell of weather, although the bergenia can typically take anything Ma Nature throws at it.

FWIW, if you are looking specifically for winter interest, you need to look wider than just perennials. While there are perennials that are "evergreen" or hold their foliage throughout the winter, their numbers are limited. You need to focus more on shrubs and small trees that offer winter interest through foliage, bark, berries or growth habit and rely on the evergreen perennials, groundcovers or ornamental grasses to help fill in. But not be the star of the show :-))

Use evergreen shrubs to form the walls of your planting and give it continuous structure. Deciduous shrubs can be used to form transitions in visual weight between these and the herbaceous plants given center stage. If there is a fence or large deciduous shrubs these can be draped with climbing plants of suitable vigor for added interest and softening, lilacs hosting hybrid clematis that bloom in summer when these shrubs are nothing but leaves for instance.

There's nothing wrong with perennials in mixed beds. I wouldn't do perennial beds unless it's someplace where I won't see it in the winter. What could be more boring in the winter than an empty bed? I went out yesterday (mostly to be out in the sun), and cut down any perennial that struck me as being ugly. For some perennials, like the mums, I left 6" stubs to catch the fallen leaves in the bed and give the crowns some protection. Some plants, like the spires of the Verbascum are architectural, so I left them. The asters I left for the seed heads. Some of the birds like them. Dark droopy leaves will fall off on their own pretty soon, but if you can't wait, go ahead and strip them off. It's your garden, and only you know what degree of winter disorder you can stand. Don't worry about killing any perennial that's going to drive you crazy all winter looking messy. Their deaths just give you more room to repeat the ones you consider a success.

I'm hoping that 8 degrees will have been detrimental to the slugs.

The problem is having just beds of non-evergreen herbaceous plants, with no evergreen shrub backdrop. Even when there is a solid fence or wall behind the border, the winter scene is much less stark if evergreen shrubs are included.

At Bressingham A. Bloom made island beds of herbaceous plants surrounded by grass, but had a backdrop of trees including evergreen conifers close by, against which the island beds were seen.

I appreciate the suggestions given for perennial care and a balance of evergreen plants in the landscape, which I have and can once again see clearly now that the other foliage has flopped.

I just wasn't sure what to do with the sudden death of the leaves on the stems due to the low temps & snow and the ugly look of the large Japanese anemone leaves flopped over on Bergenia as an example as well as flopped taller sedums yellowed & getting a bit mushy.

Do I cut back siberian iris if it's laid flat? I mentioned the perennials in question because several of them I was told to leave until dead & not cut back now.

Yesterday, in the vegetable gardens I cut back anything showing mush or signs of frozen tissue such as outsides of swiss chard, chicory, lettuces, and some chives. Most of the parsley was just fine under the blanket of snow. Potted rosemary on the porch now steel gray. Those that were moved to the unheated 6x8 greenhouse are green. I plan to snip small tips off the greenhouse rosemary all winter.

I understood that any perennial in growth now in fall shouldn't be cut back, but left until spring contrary to what gardengal48 wrote. Perhaps, I've misunderstood and confused the difference between herbaceous perennial like shasta daisy and woody perennial like upright fuchsia. In the past I've cut back daisy in fall to basal growth & left fuchsia until some growth shows in spring, which is usually quite late in April in my location.

Are these suggestions true?
-lady's mantle dislikes being cut back in fall
-sedum 'Autumn Joy' needs crown to prevent excess moisture from getting into rootball
-silver dust (Dusty Miller) wait until mid-April to cut back old stems so that you don't stimulate new growth in cold weather.

Thanks a bunch for your advice.

Alchemilla would be left until later if it had leaves on, just to make use of these leaves. Dead stalks, if anything might direct water down to the crown of the sedum. If it had a problem with rotting out here, you would put a cover over it. Dusty miller is evergreen so cutting it now would cancel out much of the point of planting it. Any stems that look terrible should be cut when noticed. Pruning is not going to make it burst into a bunch of ill-timed tender growth that then gets zapped.

It is important to make a distinction between herbaceous perennials and those that retain foliage through the winter or that have a woody framework or base (technically subshrubs). Herbaceous perennials die back to the root crown in winter - they may leave stalks (the sedum) or basal foliage (shasta daisy) but otherwise the above ground portion of the plant reacts to winter and cold weather by dying off. All of this above ground dead or frozen growth can be removed. It does not provide additional cold protection for the plant and can sometimes, as bboy notes, contribute to rotting into the root crown.

Perennials that develop a woody or semi-woody framework are typically left until late winter or early spring to get cut back. That would include things like the hardy fuchsias, Russian sage, tree mallows and sun roses (Helianthemum).

And then there are a selection of perennials that fit somewhere in between - not totally herbaceous, not woody, yet not entirely evergreen either. I'd consider the alchemilla and siberian iris among these. I leave these until they look bad enough to warrant attention. Sometimes it is early in the season if we have an early stretch of nasty weather; othertimes they get left until spring clean up if we have a mild winter.

Herbaceous serves only to differentiate such from woody plants. Some kinds such as Corsican hellebore and various spurges produce evergreen tops that maintain their full height, with a full complement of leaves through the entire winter.

Thanks for the clarification. Now to get snippy & clean up the herbaceous to crowns.

Hopefully none of your plants will be offended.