Thought this might help; here are a few of the plants that I'm not sure what to do with.

And here.

One more:

'chaven', I was just going to start a thread with a similar question. If you don't mind I will expand on your post.

There are many herbaceous plants for which one is advised not to cut back in the Fall thereby better ensuring survival over the winter. The two obvious examples are the "Butterfly Bush" and "Chrysanthemum".

To be honest I am not sure exactly why this helps these particular plants to more likely overwinter. My "hand waving" answer is that with upright stems snow is more readily "trapped" around the base thereby better insulating it from the temperature vagaries one experiences from November to March.

But what is good for the goose should be good for the gander? That is leave all plants uncut to receive the same perceived benefits? Of course this action (or lack of) is not applicable to a diseased plant.

So I am one that more often than not does not cut back until spring. And of course I know that many of you do the opposite.

This post was edited by rouge21 on Mon, Nov 24, 14 at 14:51

Yes, that is indeed one of the reasons to NOT cut stuff down in the fall. Another one, perhaps less obvious, is that in some species, a cut stem is a place for moisture to drain down into, then to freeze/thaw over the course of the cold weather, thereby helping to destroy the crown/root system of said plant. Agastaches are one famous example of this tendency, but there are many more. I like to leave everything be-to the extent that aesthetic factors allow-until spring, then do one cleanup at that time of year.

+oM

Leave them alone over the winter and start to ID them when they come up next spring. Perennials are, for the most part, self-sufficient during the cold months since they're dormant. I have extensive mixed perennial beds scattered around my little green acre and don't tend them until new growth emerges in spring. Healthy perennials (other than roses) growing in healthy soil getting sufficient nutrients and moisture need very little intervention from the grower.

The only plant for which I can guess an ID from the photos above is a possible hydrangea in the upper left corner of your second photo. The seed heads in the first photo suggest some sort of daisy but I've never seen one as splayed out as that one.

There's a forum on GardenWeb called the Name That Plant forum. When warm weather returns next spring and your perennials begin to send up new growth, post photos there (or here) for help identifying them. While I'm not that far from you (CT), your soil conditions may not be similar to mine.

Step One when gardening is to identify how much sun or shade your garden gets. Next is an analysis of soil conditions. With that information, you can determine what perennials will, or will not, thrive in your garden. There's plenty of information available to guide you.

Re cutting back perennials in fall:

Even with the same growing conditions different approaches seem to work for different gardeners.

Re butterfly bush, Rouge mentions, it's certainly not fully winter hardy where we live. My own experience with it mirrors David Tomlinson's (Merlin's Hollow). It typically lasts a number of years, but eventually dies in a tough winter. This seems to happen, cut back in fall or not.

Re chysanthemums, it depends on which ones. Some of the chrysanthemum (or closely related) hybrids (e.g. 'Clara Curtis' and 'Mei Kyo') are fully winter hardy here. Generic "Fall mums" are another matter.

Personally, I do invariably cut the plants back in our perennial beds in fall and that seems to be fine, at least here and with what we have growing.

One reason is garden hygiene, perhaps more important in our case, as there's a large number of different perennials maintained year-to-year planted close together.

Another reason, in our case, involves the many spring bulbs planted each fall. We want to have a full view of them in spring and it's quite undesirable to walk over the wet beds to cut perennials plants back at that time.

A further reason I cut back the late summer and early fall flowering perennials as soon as seems reasonable, is to allow light and rain water to get to the low spring plants (e.g. primulas) when they put on growth in the fall.

There's several other reasons why fall cleanup works well for me (e.g. being able to see what's in the beds at that time (stock taking) and access to challenging weeds and convenience for upgrading soil.

I'm sure there's personality reasons too!

I like the orderly disorder of a mixed perennial bed, but I also feel that it shows at it's best when it looks neat.

Chaven, here's what I do.

* Clean up dead, soggy perennial leaves, like hostas, mainly because they're so unattractive.

* Allow healthy, non-diseased dried leaves to stay on the ground as natural mulch, unless the leaves are so waxy and/or big that they'd get matted. So oak leaves (too waxy) get vacuumed up for the compost bin, but the crape myrtle leaves stay and rot on their own.

* Leave all woody stems up for the spiders and praying mantis to lay their eggs. I rely on them as natural predators.

* Leave all flower heads and seed heads for winter interest, unless I don't want the plant to self-seed.

* Leave all plants that dislike a wet crown, such as euphorbia.

Re butterfly bush, Rouge mentions, it's certainly not fully winter hardy where we live.

That is for sure an understatement SB!

I have lost count the # of times we have planted BB on our property and have lost it by the second winter max. I love this plant and of course against my better judgement planted two more this past summer. (They are extra petite BBs and so can be protected using this tent. I covered one this way and the other which which you still can see in the photo, adjacent to the other, will get only leaf mulch).

SB I understand all your reasons for cleaning up in the Fall...a couple I hadn't considered. Thanks for summarizing.

Thanks to your post Rouge, I looked up smaller new butterfly bushes. Hadn't been aware of them.

The large old varieties are too large and raggedy for our own small garden.

Your post indicates that smaller might make winter protection more feasible.

I hope you can tip the scales against natural selection!

The 2 new ones I planted this past summer are called "Pink Micro Chip" and their maximum dimensions listed are 2 feet by 2 feet (good for a small space and easier to protect).

(And FWIW this variety was a silver medal winner for best new plant at the "Plantarium" in the Netherlands for 2014.).

i think the buddleia problem has got to be moisture. here in nevada the only way to get rid of them is to pull them out. mine have survived -16f with no problems. i do know that in britain they cloche them, not to protect from cold but to keep them dry. we are in an exceptional drought here in n. nev-1/4 in. of precip in the last 8 months-but it's always pretty dry.

Interesting davids10.

We have heavy clay (albeit extensively upgraded) and the season of maximum (liquid) precipitation is fall.

a lot of western natives will do fine in frozen dry soil but check out in frozen wet.

fwiw
The last pic looks like sedum. It's fine to leave it's floret/seed heads on over winter for birds.

You may already see this sedum budding from the crown. That is normal, nothing needs to be done at this time. Clean up the dried stems in spring.

In my area, leaving the dead/dry stems of many plants over winter will serve to catch fall leaves for a natural winter protection mulch.

i think the buddleia problem has got to be moisture.

But aren't buddleia quite prevalent (invasive?) in the wet PNW?

Rouge, the coastal PNW has wet winters, but not *COLD* wet winters.

We had a BB quite a few years ago. One day I noticed the roots (shallow) were traveling quite a distance from the base of the plant . We have a septic system and I became concerned. Also it seeded itself annoyingly. Then, I read of its invasive tendency in my climate and could see why!

A weird thing...I found a foot tall seedling a few months ago across the driveway about 25 feet from where the original plant was growing. Must've laid dormant all this time. I had to chuckle. I spose it could have been pooped in...I'll never know. I decided to let it grow, I'll check on it next year.

UPDATE:

Here is this same scene as pictured just above, with just a glimpse of the 'tent' showing: