Well, quite a lot for me I am sorry to say. A lot of them were new to my garden too. Not sure if that should make me feel better or not???

Eremurus (foxtail lily)

Fritillaria imperialis 'Lutea Maxima' (though for some reason the orange one came up fine?!)

Hedysarum hedysaroides (french honeysuckle)

Salvia lyrata 'Purple Volcano'- ugliest plant you have ever seen, so no big loss ;-)

Arisaema urashima (no signs of life)

Corydalis 'Silver Spectre' I ordered last spring. Think it might not be as hardy here as some sites say. I do see what I think is a sprout, so I will say it is iffy, not dead!

Cymbalaria muralis- it did so great last year that I have no clue why it died! I see seedlings around the spot so perhaps it reseeded?

Erodium 'Bishop's Form'- though granted it looked terrible over summer..
CMK

I loved the look of erodium, but most sites said Zone 6. We've had zone creep here (from 5b to 6, but I don't believe it yet) Then I noticed a few places gave erodium a zone 5. I think it is probably marginal in zone 5.

I've never had a corydalis winter over (or even summer over) except lutea. Then I'm not sure it winters over, but when there's enough seedlings established the point is moot.

i like to find blame in anyone or anything .. but myself ...

winter did kill a few conifers ...

ken

I lost a boat load of hostas that over wintered in pots because they did not have adequate drainage, ie, the soil was peat based not pinebark based. So I knew better and lost at least 30 pots over winter that I was growing to be big enough to use this year.

Idabean, have you tried growing Corydalis elata? I have it growing here in zone 5a Can. This is its 2nd Spring and its already about 6" or more. I planted it in late Summer when I bought it. We haven't had much warm weather but it hasn't stopped this plant. Its way ahead of my hostas.

-idabean, think the tag on the erodium did say z5. Think the problem was that I didn't plant it in the ideal location. It was looking pretty bad by fall anyway. I started some E. gruinum from seed this past year and hopefully it proves to be a better grower! There was a thread that was going here awhile back about Erodium, if you are interested... Erodium Hardiness?

What Corydalis have you tried besides lutea? I have had elata a number of years and it has done very well. The C. quantmeyerana 'Chocolate Stars' I got last year came back stellar and is doing very well too. Can't say the same for 'Berry Exciting' though ;-(
CMK

I'm so happy to report only one loss...a white old fashioned bleeding heart, dicentra spectabilis, that was a few years old, so not sure why it didn't return. Doubt I did anything to it. The pink ones all returned just fine.

I lost a ton, somehow I even lost my bachelor buttons. Although I am truly hoping that is just this super slow spring that has everything wanting to sleep in!

funny thing for me, I lost a Shasta Daisy perennial after 3 years, but every single annual dianthus I planted last year came back better than they ever looked last year. My pink forget-me-nots barely came back this year after being overloaded with them last year.

2 of my so-called Gypsy Queen Hyacinths (mine are pink, not peach) didn't come up and one pink iris didn't survive. One of the 2-toned pink perennial dianthus didn't make it either. I can't seem to keep this type alive. They survive the winter, but once the snow is gone & it gets one day below freezing & they're toast. All in all though, I would have to say that this was my one of my better years....so far.

I killed a Princess Diana Clematis. It died after I planted it. I've never seen a Clematis do that. Maybe it'll come back from the roots next year but I'm not expecting it to.

A little early here for an official count as there are still things coming up. But so far one hosta in a pot. Evidently -30 this winter was to much for it even stored in the garage and so far no sign of the senna planted last fall. Also was hoping for seedlings from Angelica gigas...maybe they will show up when the weather warms up??

I have three clematis, type 2, so I cut them back in early spring. But they look dead. I think they should show new growth by now. Clematis hate me. Bad karma from leaving one behind at my old house where it wouldn't get watered without me. Why, oh why, didn't I dig that one up and bring it with me? I still have hope and have three new ones for another spot. The Clematis Gods have to forgive me someday, lol.

Three Autumn Light astilbes are MIA. Other kinds of astilbes are up. These were so bright and beautiful, but the tag doesn't list a zone. But I'm sure the nursery sign for Autumn Lights said it was good for my zone because I'm careful about that.

Dwarf monarda (bee balm) didn't come back in two different spots in my yard. The tag (Lowes) listed them as hardy for my zone 5, so I'm ticked off about these not showing up.

I lost a lot of perennials - but I didn't kill them, the voles did! This is the first winter I've had vole damage. The garden beds had a mulch of leaves, plus 2-3 feet of snow on top of that, and apparently the voles were having a party underneath there all winter.

Some plants were completely eaten; others had some or most of the roots eaten, but they are still sending up shoots. I had a couple HUGE Baptisia 'Twilite Prairie Blues' that are now spindly things, but at least still alive.

Some of the losses -

2 out of 3 Joe Pye Weeds
Most of the Helianthus Lemon Queen (this might be a good thing, as it's a very aggressive spreader)
Boltonia Snowbank
Helenium 'Mardi Gras'
1 Cimicifuga racemosa

Did we have a worse winter than usual for zone 5?

My 1 yr sweet autumn clematis hasn't returned.

Another established clematis, type 3, didn't return. If it's Venosa Violacea I'm going to be upset, I have to check my garden "map".

My container spruce, which I wrap well each year and made sure to water during warmer temps is really brown.

My 2 year Fothergilla Major Mt. Airy died.

My 1st year Willow Hakuro Nishiki looks completely dead.

My 3rd year Golden Spirit died back to the snow line, but this didn't happen in prior years. My "Grace" came back a real winner, no dieback at all.

My Sombreuil Rose bush, which I usually bury the crown, wrap in burlap and cover each winter, though the only thing I did this past winter was cover the crown and nothing more, returned with very little dieback to my amazement. Better than any other year. Go figure.

Some hostas, which I was warned last year after purchasing that they aren't hardy, never to be seen again.

Some groundcover sedum which probably never had a chance to establish -- nothing.

Also lost a Weigela My Monet, thankfully still under warranty.

Very Bad year!!!!

Oh, and don't fret about the Asters. I had several varieties and they've all disappeared. I suspect it's the rabbits.

Somehow I can not get mints to survive.
The Russian sage cutting I took last year seems to have given up the ghost. It did well for a while.

Are there hosta that aren't hardy in zone 5? I've never heard of such a thing!

I think the drought hurt more than the winter did. I watered like CRAZY all summer and most of my stuff came back. My friend didn't water and lost a ton of stuff.

Perhaps that was really the major factor, if you were in the drought area?

Maybe "hardy" isn't the proper terminology. Not a good performer???

I wouldn't say "I" killed them

voles ate my favorite primroses, and rooted through some sedums. why not eat the other primroses that I have tons of?

my favorite yarrow - anthea, seems to have dwindled away

some tiny hostas I had just didn't make it through the winter

The thing is, I might not even know they were missing except I had them on my trade list, and when I went to look for them, they were gone!

ahh, gotcha kimcoco! :) I've grown a lot of those lol

I have an Aster that seems to be dying a slow death, but I've already whined about that. :)

None of my bachelor's buttons/Centaurea has come back. Don't understand - had it at my other place and it thrived on neglect for years.

Killed a reblooming lilac cutting. Well, I didn't, but a late frost got the buds and it croaked. Too bad - it was doing really well till then.

Several of the cuttings I stuck in the fall didn't make it, but that was to be expected, as I didn't do much except just stick them in the ground and say, "You're on your own." LOL Was too tired to do much else by then.