I think you're going to have to define your terms first -- "best" in what regard?

Oh, I guess I mean most reliable and long blooming in this area (Michigan). I'm looking for the plants that people have the most success with. Thanks for any help anyone can give me.

Although some of the variegated brunneras are lovely, for the differece in price, I like plain green just fine. This is a good plant for zone 5 - cold hardy, healthy and deer seem to walk right past it. Even in Z5, though, it can get wilty if it gets too hot or dry. Plant it in part shade and keep an eye on the moisture in the soil.

I love all campanulas, but they are beloved by deer and woodchucks. If you have either of these, campanulas will just break your heart. If you are deer-free, still keep in mind that many of these plants last only a couple of years before conking out. All that said, I love my little c. poscharskyana and c. cochlearifolia. Of the larger ones, I usually invest a little time each year to start c. medium from seed. I bought c. rotundifolia ('Olympic' or 'Olympia' or something like that)from Bluestone a couple of years ago, but they died after two growing seasons.

Digitalis. D. purpurea are biennial, so you can expect them to die after one bloom season. They are also, however, easy to start from seed, so you can either just get seeds or you can buy plants and save the seeds for planting. I've also grown other species that are true perennials (d. parviflora), but they weren't as showy as d. purpurea varieties. I never got d. mertonensis to overwinter in zone 5 (I tried twice), but there may have been all kinds of reasons for that.

Gaura's hardiness in zone 5 may be suspect. I hope you hear from someone else about this.

Salvia: my favorite is one that will not overwinter in zone 5 (or zone 7 for that matter), but I love it so much I dig it up and bring it indoors for the winter: s. guarantica 'Black and Blue.' It blooms for a long period in late summer and through the autumn. I also have s. uliginosa, which is an astonishingly prolific bloomer and my bees adore it, but it also needs to be dug up. In my garden last year, it bloomed from early summer until, well, until winter. Bluestone sells s. uliginosa, but 'Black and Blue' tends to lurk among the annuals at local garden centers. I used to grow 'May Night' in zone 5 but thought the flowers were too dark to make much of an impact.

My favorite veronica is a short, spreading one that Bluestone sells - can't rememebr the name. Doesn't have a long bloom season, but the foliage is nice all summer. I also like 'Bergen's Blue' but that has an even shorter bloom season. I got 'Crater Lake' last year from Bluestone, but I haven't seen it do its thing through a full growing season yet. People have told me it flops.

Of the phloxes, I love 'David' best It's like big fragrant ice cream cones growing in the garden! In a vase with cobalt blue delphinium chinensis it's stunning. 'Nora Leigh's' foliage is nice (variegated), but I think the leaves and the flowers clash while it's in bloom. Phloxes are generally susceptible to mildew, but both 'David' and 'NL' stay pretty clean.

I love all nepetas - it's not possible to have too many of them! 'Six Hills Giant,' 'Walker's Low,' 'Fat Cat Select,' n. subsessilis, they're all great, all deer proof, all disease and pest free.

Alicate
check out winter sowing forum, read up FAQ and look at wintersowing.org.
It is easy and inexpensive way to start as many plants as you want for pennies. YOu can experiment to your heart content as well. One problem- it is very addictive- LOL

Do also search for heuchera threads here; there have been several in the past months with a lot of good discussion about varieties people like best and why!

Agastache foeniculum will be the most hardy for you, though if you plant A. cana or possible even A. rupestris properly, they may overwinter. They are western agastaches and resent wet winters, but if you have sandy soil, plant them high, and don't cut back the foliage until spring, they are likely to overwinter. Treat gauras the same way.

Not sure which Digitalis Bluestone offers, but D. obscura, D. thapsii, D. ferruginea are true perennials.

All of the above are deer resistant; phlox is deer candy, at least P. paniculata is. The woodland phloxes much less so.

Penstemons are deer resistant and well worth a try. Among the longest lived ones are P. 'Red Rocks'; a long bloomer too.

Campanula--I love the C carpaticas but they don't live long, at least for me. I planted one for a friend in Maine back in the early 1990's and it's still going strong. We have cold her but not much snow so that may make a difference. It might do great in MI. The peach-leaved bellfowers seem to live longer but the bloom season is shorter. C.poscharskyana is a cutie too/

Phlox--David is excellent. I agree that Nora Leigh flowers and foliage clashed and it was not long-lived for me, seemed weak and feeble all of its short life.

Digitalis--I have a perennial yellow but don't remember it's name. I like it a lot in the edge of the shade garden. It reseeds prolifically which is OK for a large space but it will eventually overtake an area. I pull some out and throw them away or give them away.

Penstemon- Elfin Pink blooms repeatedly if deadheaded. It's a bubblegum pink and makes a nice little mound of foliage.

Veronica--Sunny Border Blue blooms all summer. Crater Lake Blue is my favorite color.

Have fun!
VG

I like Bluestone - the plants are small but very healthy, and grow fast.

I grow phlox 'David' - it's very nice, and benefits from staking. No mildew problems for mine, either.

Gaura has not been hardy for me so far, although all the garden centers sell it up here.

I had veronica 'Giles van Hees' for quite a while, until another more vigorous plant smothered it. I'd like to try some of the taller veronicas, but I've been staying away from Bluestone's catalog since I placed my early order this January - too tempting on too small a budget.

Heucheras grow fairly well in my zone, given partial shade and regular moisture (they don't do drought or sun well).

Nepeta does VERY well in full, dry sun up here. And the deer don't touch it.

Hardy salvias are good workhorses up here. Some need more maintenance than others. For example, 'May Night' needs to be deadheaded or cut back several times each summer to stay looking tidy - it gets scruffy and straggly pretty quickly. Annual salvia 'Victoria' is a wonderful plant.

Hope this helps.

Laurel

From a fellow Michigan gardener, the following are relatively foolproof and may give you some contrast from what you say you already have:

1. Agastache. Try Blue Fortune, or A. cana. A. rupestris is also outstanding and a fully hardy plant for well drained dryish soil
2. Campanula. Take your pick, so many are good. Try some of the taller ones, C. lactiflora, C. persicifolia, Kent Belle
3. Heuchera. I am not a big heuchera fan, foliage often looks garish to me. How about H. americana, a good native? Not sure if Bluestone sells it but it is a good plant.
4. Brunnera macrophylla. The straight species is underutilized and an excellent tough as nails garden plant. It seeded happily in my old garden, in a useful way.
5. Phlox paniculata. David, of course :o)
6. Digitalis. Take your pick, any of the purpurea selections will make wonderful plants in the garden and will reseed as they should. D. obscura, D. ferruginea, and D. lanata are also great plants for full sun.
7. Gaura. Careful here, these are not always hardy in MI, need lean soil and good drainage. The pink types are not hardy for us. I had consistent success with 'Whirling Butterflies' and I would stick with that one.
8. Nepeta. Everybody has Walker's Low now, for good reason, it is a superb garden plant. Bluestone seels 'Souvenir D'Andre Chaudron', a selection of N. sibirica, and it is a great catmint and quite different - 3' tall and more upright than mounded. Blooms for 2 solid months. You will love it. N. subsessilis is also a good choice.
9. Penstemon - red rocks or Pikes Peak Purple (I think that's it) are great choices.
10. Persicaria. What you choose depends on what size you want. They are all quite different. P. polymorpha (big and shrubby), P. amplexicaule (medium, red/pink flowers long bloom late) are good choices if they have them. Polygonum bistorta (closely related, used to be same genus), is a good low grower for dampish spots.
11. Salvia. I would stick with one of the S. x superba choices if you are new to them. 'May Night' is very reliable and one of the longest bloomers. 'Blue Hill' is bluer and also great. A little known plant that is great in the garden and your neighbors won't have is S. forskahloei (my spelling is probably off). Bluestone carries it and it is a great garden plant -- large foliage, airy sprays of flowers, bigger than the S. superba cvs, blooms a long time mid-late summer.
12. Veronica. Many good ones, take your pick. Icicle is an old, long blooming white cv that will bloom abundantly the first year. Don't forget the veronicastrums, excellent tall close relatives which should be in all gardens in our climate.

Here are my favorites of a few of the flowers you mention -

Brunnera - Brunnera "Jack Frost" is expensive, but it's one of my favorite shade plants. Its silvery leaves really light up a shady spot. Plain green brunnera is pretty in a more subdued way and has also done very well for me (it self seeds a bit). Both have lots of blue spring flowers.

Nepeta - I have Blue Wonder and it blooms all summer. It's 12-18" tall. You might also consider calamintha nepetoides, which has a similar, but more delicate form, than nepeta, and also blooms a long time. It may seed a bit.

Salvia - East Friesland, Blue Hill and May Night are all about 2' tall and bloom spring to fall. Caradonna is taller (about 3') and has dark stems. They all get a bit floppy late in the summer, so I cut them back hard and they rebloom.

Veronica - Goodness Grows (purple) and alpina alba (white) are both compact (about a foot tall) and bloom from spring to fall.

Juliet

THANK YOU all very much!

After ordering some plants that I needed for an established garden that needed to be finished I was able to order just for some some of the varieties you guys suggested. I am most excited to finally have a salvia and a speedwell. I think I am going to print this list out for future references. Thanks again everyone!

Cate

Agastache Blue Fortune is such a beautiful, fragrant, long blooming plant. Watch out for the pink varieties, they don't seem to last through winter and Butterfly Blue reseeds all over.

Campanula, Cherry Bells and Wedding Bells are pretty and heavy bloomers but spread pretty fast. Sarastro-not as appealing to me but better behaved.

Heuchera, Palace Purple is pretty fail-safe. Peach Flambe is gorgeous red and grows nice for me.

Brunnera, the standard green grows the best for me. Reseeds.

Phlox -Amethyst, Davis, laura -love them all...

Nepeta, WL

Penstemon -Rondo Mix, Red Rocks, Prairie Fire, -needs good drainage and many are not zone 5 hardy even if the nursery says it is.

Persicaria, Firetail and Polymorpha are outstanding. Firetail blooms forever!
\ Salvia, Caradonna, May Night, Blue Hill all good

Veronica, Giles Van Hees for short pink and Pink Damask for a 30" is amazing - long blooming 5-6 spikes of light pink with good form. Icicles is also a nice white choice.

Good luck with your garden!

Digitalis, Obsura doesn't do well for me.lMertensis...(sp?), doesn't make it through winter, lutea is perennial and I've had it for 6 years, Pam's Choice didn't come back. I plant Foxy and let it reseed.

Gaura, Whirling Butterflies is hardy for Z5.