Gaura

I forgot a few (all As):
Ajuga
Achillea
Agastache
Artemisia

Gaura, really. I've both pink and white for 7-8 years now.

Most of those I have no trouble with. Gaura, however has never overwintered for me.

Also Scabiosa. Doesn't matter what i do, it doesn't return.

You must not have tried all of the hundreds of perennial geraniums yet! You could heave the macrorizums on blacktop in Arizona in July and they'd probably come back in October.
But you weren't asking us to put salt in your wounds
I cannot keep gaura, but neither can most of us in New England zone for 6
Bergenia may not die but it looks so rotten by spring it should die. Hanging on by its fingernails, so to speak
The newer echinaceas in the "Saul" series (Sunrise etc) etc but that's not my fault
I can't begin to remember everything that's died. I'd never pick up a trowel again if I did.....
But now you've got me thinking....

Gaura wintered over one year for me but not the next. I think the year I lost it we had less snow cover. Ajuga, has not wintered over in my garden for some odd reason. I kept Bergenia for 4 years, no blooms, horrible looking foliage 80% of the time. Shovel pruned it this spring, but it was definitely hardy here. Have lost 'Tutti Fruiti Agastache last winter but Honey Bee Blue comes back faithfully every year.

sc_gardener, I thought Valerian is supposed to be a very persistent plant that can become a nuisance. Coreopsis, Campanula, Alchemilla,...I thought all of those were hardy to zone 5 and will grow in clay soil. Wondering if drainage is the problem for you, or am I wrong about the hardiness of these plants?

prairiemoon is correct - it is not an issue of cold hardiness.....all listed are fully hardy in most areas of the country.....but much more a question of soil conditions or other climate limiting factors like excessive summer humidity. Many native prairie or xeric plants require exceptional drainage to thrive (especially during winters) and dislike much humidity.

Several of the species listed are almost weedy in my area, due to their ability not only to thrive and grow well but also reseed freely.

As with the "easiest perennials" thread, what works well or doesn't will vary widely from location to location and specific garden to specific garden :-)

what gg said.

Hmmm. What have I killed recently? Bearded iris are rotting (they are planted near plants that require a lot more water). I killed a Dogwood and a Magnolia (both expensive). I killed a beautiful butterfly bush by moving it last Fall. I lost a tree peony to what I think was some type of rot. I lost 1 of 6 Endless Summer hydrangeas this past winter...no idea why, completely random, it was fine last year.

The native soil here is horrible. Hard clay with little bits of rock. Most of my gardens were created by digging out the clay, adding sand and then pure compost on top. I plants right into the compost and most everything does beautifully. Wind is my biggest issue, and DH over watering (I think he killed by Dogwood and Magnolia by drowining them, wind didn't help the Dogwood either).

Oh, I forgot to tell you about the "Summer of the voles" (try to imagine a horror movie where voles destroy $$$ worth of established hosta).

I keep saying I'm in zone 5 but it's almost 4, maybe. I like to think here, near Concord NH, is zone 5. In 2007 I moved from a shady yard to one with plenty of sun. The herbs (sage and alchemilla were planted in an area that got sun part of the day when not shaded by a small maple tree. They did fine and much better than they were doing in my old garden which had more shade and less good compost.
This spring I moved to culinary herbs to a very sunny location around a small kitchen porch. Tomatoes had grown in the bed for 2 years but with last year's blight problems I decided it was time to rotate them out. I had composted manure last fall. The culinary herbs love it and have turned into small bushes. I do have trouble with the colored sages but one with reddish/purplish leaves did survive the winter. It's still a puny little plant.

Last year I put threadleaf coreopsis I had gotten at a plant swap in a new garden bed. I love the lasagna method of building beds and I top them with composted horse manure. This bed has plenty of chopped leaves and grass clippings. The geranium was put on the west side of the house but in ordinary dirt. Since it's against the foundation of a heated garage it probably benefits from the building heat during the winter.

See if you can correct the drainage issue. Do you have lots of earthworms in spring? When my good soil is dry, it is crumbly. When my poor soil is dry it is powdery.

Good luck. I know losing a plant is very disappointing. I lost lots trying to grow sun lovers in part shade.

I have lost tons of perennials that either didn't overwinter or they perform poorly or they just die! Not to mention my negligence or bad decisions about placements. Lavender, Scabiosa columbaria, Stokesia, Coreopsis 'Sunrise', did not overwinter. Last year my Agastache 'Blue Fortune' died out after years of blooming, and the Veronicastrum never did well so I yanked it. Have lost a weak Phlox paniculata cultivar or two over the years. Etc. etc.

If I went through the collection of plant tags I've accumulated over the last 6 years I would probably be amazed/appalled at how many plants are gone now!

Ironically some of my winter-sown Gaura lindheirmi did overwinter and is blooming now, but knowing they like good drainage, I planted them on a shallow slope with sandy soil. Who knows if they will be long lived though?

SC Gardener, I garden on extremely compacted clay sub-soil (all topsoil was removed by the builder and trucked away when our house was first built). Parts of my Z5 garden are only a few years old, other areas have been improved by gardening on them the past 15 years or so - but it has always been a very hard go, especially since I have not been allowed to raise the grade in most areas of the yard.

FWIW, from your list,

I have been able to get most perennial geraniums to grow. Geranium cantabrigiense (x) Biokovo, also the similar pink one Karmina, Geranium cinereum Splendens, Geranium endressii Wargrave Pink, Geranium oxonianum Rebecca Moss, Geranium sanguineum & sanguineum Ankum's Pride, have all been in my gardens for more than 5 years, plus several others that have overwintered for a couple of years. I would give the geranium family a retry if I were you.

Anemone - there are many kinds - I have had good success with two bulb varieties Anemone Blanda and Anemone sylvestris, both perennialize wonderfully (I grow them under trees where it is drier). However, I had a very tough time getting the perennial Honorine Jobert to thrive in my garden - 3 plants at 3 times (9 total - I can be stubborn lol) to get 3 survivors, 2 were pretty stunted after a few years and removed, the other is currently growing like a weed. I was told on the GardenWeb that one of the problems with them here is that they are often for sale in the fall (when they are pretty in bloom) and need to be planted in the spring to settle in well.

Valerian over-wintered for me for several seasons, but had very little spread/growth in subsequent years and just wasn't there one spring. I didn't try repeatedly to grow them as I did with the HJ anemone because the color of the ones I planted were washed out looking.

Delphs look lovely but only last a few seasons. I replace/add to them fairly frequently.

Saqe - sage - salvia, I presume, vary somewhat but some will grow well in the drier parts of my garden. May Night & Caradonna do well for me and are long-lived. Marcus, a dwarf variety, gave me only 2 years. The culinary sages grew very well for me, but do tend to get woody fast, and I replace them every few years. All of them grow best for me with a little gravel in the planting hole, or near rocks or concrete walkways, etc.

Firewitch dianthus is the only dianthus that is truly perennial for me. I was very surprised to here that yours died. Other kinds are very iffy, even to overwinter a season or two. The biennial ones, however, are usually capable of giving 3 to 5 years - don't ask me why!

Ornamental grasses - miscanthus, panicums, calamagrostis (called something else now) all do very well, while the pennisetums are a bit more difficult (try the rocks/gravel thing for some of these). The silver blue things (except for the panicums) seem to be very questionable here, for example, Blue Oat Grass works best as an annual in a pot and Elijah Blue fescue survives but heaves a lot. Sedges make a good replacement for some of the smaller grasses.

Most campanulas are short lived for me, even the dreaded spreader glomerata only managed to be a well-behaved, but fairly tender plant for me, which would die out for no reason every 3 or 4 years.

Coreopsis - only long-lived one for me is Moonbeam, the rest 3 years tops, with the really bad pink ones strictly annuals. Creme-brule (multiple plants) lived 2 seasons only. I eventually found it more fun to buy various coreopsis seed packs in spring and sprinkle them in pots for mid/late summer placement in those inevitable dull spots in the garden.

Lady's mantle grows like a weed for me and seeds into every crack in the sidewalk as well as the soupy parts in the low areas of my yard, in full sun or full shade. Maybe you could retry that one.

From your second list - ajuga, achillea, agastache, & artemisia are all problematical for me.

One of our local nurseries cautions buyers about using Ajuga as a groundcover, others sell them in flats for unsuspecting buyers. Caitlin's Giant ajuga is a definite annual for me, no matter where I plant it or how I plant it. Burgandy Glow usually overwinters, but may disappear
(the whole big patch) at anytime thereafter. Grows best under the eaves or next to a walkway in my garden, the same with Chocolate Chip.

Achillea' Moonshine is the easiest one for me - will grow, but not spread around excessively (or even all that much) and has lasted for years (over 10 years). Paprika and Fireland do fine in the upper garden near the patio, as does Cerise Queen, but it's counterpoint in my pink garden Appleblossom faded away.

Agastache - only one you see around here for sale is Blue Fortune. It is supposed to handle somewhat damper conditions than most Agastaches. I have never tried it. I have stayed away from all agastaches because of my drainage issues and because they are too large for my gravel garden. I usually pot grow at least one Agastache a season.

Artemisias drive me insane. They won't grow in the garden proper, but overspread their space in my raised gravel garden and spread all over the place. I think I've tried them all with absolutely no good results. I now rely on Lamb's ear - it may rot out sometimes, but always comes back the next season. Just rake out the mess, stick whatever looks reasonably possible to regrow, and forget them. Lamb's ear is about the only silvery plant I can grow - for blue grey green I use Walker's Low catmint, which can get messy but always returns faithfully and can be pruned to shape them and for multiple bloom cycles.

Guara (listed by others) - the only hardy variety for me is Whirling Butterflies, pink ones are strictly annuals. Whirling is bone hardy and is currently spreading a bit too much for me (likes the front edge of my beds where they are too tall). I also helped them along by moving all the plants from one corner of the yard to another (while flowers are white - there is still a lot of pink to them which I didn't like in my yellow, blue and white garden) but the removed ones regrew in their original spots as well as in their new locations, bigger than ever, so I unintentionally doubled my quantity. Every year I dig out a few more and trash them.

Scabiosa - I bought 12 plants of Blue Butterfly one year when these were a "hot" plant. They bloomed like crazy, but none returned, never tried again. I did have a S caucasica Perefecta Alba which over-wintered a few seasons and then died out.

For myself, I would like to add to the list - the heuchera.
Some live forever, some die after one season, and lots of them shrink year by year. I know they are wonderful some places but not in my garden. Hardy for me are Palace Purple, Green Spice and Caramel, also one of the more silvery purple ones, with prominent veining whose name I no longer know, possibly Pewter Veil. The rest are a big question mark, and I have tried lots of them.

Guess I'm going to have to did my Scabiosa out and keep it in the basement based on the comments here. I'm a first year gardener and wonder what will return next year. Moreover, I wonder what will survive the summer? My plants are very grumpy because of the heat!!

merindah, I treat Scabiosa as an annual at this point. It's such a bloom machine that I don't mind the expense truthfully.

Echinaceas and fall mums do very well for me, so I am thinking of trying some daisies of some sort. Years ago I had a clara curtis mum that was great but construction got it. (still can't get those mum latin designations right though!)
I was just musing on how many I have killed over the years.
I had moonbeam coreopsis for several years, then it died. But "baby sun" did not overwinter at all.
I have found that I have more winterkill in wet winters when there is ice than in winters with snowfall. and for a cycle there we had measly snows here in the winters.

Black and Blue Salvia actually came back this year, but the last time I planted it, it was an annual for me. I was very surprised to see it return in the spring. I had originally thought it was a seedling from May Night until the foliage got taller and I saw the lighter color leaves.

I lost one Guara but got a seedling from it, and this seedling has returned for 3 years. And it has produced more seedlings!

I also lost a Blue Flax after moving it from another house and having it return the following year. It produced a seedling though, that is returning for me. I also save a few seeds, just in case...

I just feel really lucky because my dwarf Delphs that were grown from seeds by a local friend have returned for their 4th summer. That is highly unusual here.

All of my Big Sky series Echinacea - 4 different ones - are also in their 4th summer. They were purchased on ebay as plugs. This year, I let two volunteer seedlings bloom and both look a lot like Summer Sky. The branching on one is very good, even better than Summer Sky.

My 2 Fama Blue Scabiosa and 2 Issac House Hybrids all returned to bloom this year. We will see how they do next year. Pink Diamonds, a dwarf, seems very hardy and comes back every year. Another one, that I received in a trade, which is tall and lavender is also hardy here. One that I had grown from seed that I lost is an annual variety, so I can't count that. I grew Beaujolais Bonnets from seed one year, and it did not return the next spring.

I lost 3 lavender "Lady" plants at our last home. The two that I have now have been here since we moved in in the fall of '06. I received them in trade, so I have no idea "who" they are. But they are so large now, they resemble woody shrubs. And one produces extremely fertile seeds. I'm forever digging and finding homes for its seedlings. I'd be glad to save seeds from the this plant if anyone wants some. It seems to be very, very hardy here.

I lost two Nanho Blue Butterfly Bushes - one that I dug and moved from my daugther's home, and one I bought to replace that one. Both were grown at our last house - a mile down the road from where we live now. I have had success at this house with Pink Delight, Dubonnet, Royal Red, Black Knight, and a species seedling that is lavender. The seedling bloomed at least 2 to 3 weeks earlier than all the other ones, much to my and the butterflies delight.

We had the landscape in the front of house dug and replaced when we had a brick walk put in. I bought a "zone 6 hardy" Gardenia that never returned, replaced it with a Caryopteris that never returned and there was a dwarf blueberry bush next to it that only lived two years and it never did very well either of those years. There is a large daylily in that spot now and it's doing well.

We have very hard clay soil with lots of rocks. We dig very large holes and amend the soil when putting in new plants. We also mulch heavily every year, so the soil should also be improving from the breakdown of the pine bark mulch.

Linda

Well I've lost plants mostly because I didn't realize that were the wrong zone. White potpourri lavender which I tried to grow twice before I realize it was z6 or higher. Tried 4 times to grow butterfly bushes and dogwoods trees to no avail.
Lost several roses when I first started growing them but am getting better at keeping them alive. The last one that died was with me for seven years before a late freeze killed it. I have wonderful clay soil that my earlier garden tools where damaged by. I do amend the soil when I plant but mostly I use earthright twice a year to help break up the soil. And well gaura is basically a weed in my yard. I give away many seedlings every year can't bare to compost them. Though I seem to be sending a lot of them to Texas lately. I love the pink one, not a big reseeder have yet to have any offspring.

sc_gardener, you should not have problems with delphiniums in your zone, the colder the better. You probably bougth Pacific Giants(with names of the Round Table Knights), which are very short-lived. Try pure Delphinium elatum cultivars.

Japanese blood grass, Imperata cylindrica 'Rubra'-- rich soil, mulch, crowding from other perennials, & winter wet did it in. After reading about warnings that it's invasive, I planted them right next to tall sedums ('Autumn Joy') to corral it, but maybe that wasn't a good idea.

japanese blood grass is a slow grower for me in zone 5, not spreading much at all, and I've had it for many years.