A hardy salvia will bloom pretty much all season if you keep it deadheaded or cut it back after the first flush of bloom. You can also keep it bushy and compact if you prefer that way.

What about Rozanne? A lot of people seem to like that one.

There's always Biokovo in that short-but-not-too-short category of geranium...some people don't like the smell of her roots though.

http://geraniaceae.com/cgi-bin/detail.py?id=263

I've started to see her widely for sale this year, even at the box stores.

Here is a link that might be useful: Gothiclibrarian.net

I was thinking about Rozanne, but someone mentioned she was similar to Johnson's Blue so I kinda mentally dismissed her after that. Is Rozanne a bit more tamed that Johnson's Blue?

I do like Salvia...I've already got six grouping planted in the front yard. I think I'd like to try something different for this area so I'm not repeating too much.

Alchemilla mollis, also known as "Lady's Mantle" -

I have pink and a yellow (moonbeam) coreopsis planted in front of purple coneflowers, liatrus and lillies, then annual lobelia in front of that. The perennial coreopsis is a little slow to bloom, but once it starts, it goes until frost. This year I mixed in some annual mahogany coreopsis, and its already blooming now. It makes for a lovely "fluffy" border edging.

I don't think Rozanne is tidy enough for the look you want. I have her in the front in a couple spots in my border and she sprawls all over the place. Nice effect in some spots - like around rose feet, but annoying in others. She becomes even more gangly in less sun.

I agree about Rozanne -- very sprawly, more so than Johnson. How about Veronica? It comes in lovely blue and pink, and I use it in front of taller plants in just the way you say you want. I'm also looking for something else for the front of the border too, in pink. G. Biokovo is great (and pink), but looking for something else not to repeat. So if anyone has any pink thoughts, I'd appreciate hearing them too.
lucia

as in Beeblebrox?
one of my favorite heroes. both Rozanne and Cambridge may still be too short for what you want; what about Striatum? you would have the pink but with a streak of white and it's more full and will hide your legs (mine is about 10 " in full sun).
or have you considered any of the variegated medium height sedum? Vera Jameson comes to mind, and you'd have color interest even when not blooming.

Geranium sanguineum 'Elke'

That would be my vote - right hight and very long bloomer

How about dianthus? Not the ones you can buy in 6-packs -- those ratty little annuals they sell in local garden centers drive me crazy (after the first flush they never look good), but there are some true perennials with attractive gray green or blue green foliage that look great even out of bloom. Excellent as "shoes and socks" for leggier plants. Hardy down to zone 4 at least.
There are many different varieties and lots of places to get them, but here's one that might fit the bill.

Kay

Here is a link that might be useful: Dianthus plumarius

You'd have to check the hardiness of these & if they fit your climate as well.

Corydalis lutea blooms yellow w/ delicate green-blue lacy foliage all summer here in western WA as long as kept moist with mulch & weekly watering. Might be more of a filler rather than an edger because mine is taller than 10", but then everything is a bit taller here with frequent spring rain & dappled shade from tall trees.

Serbian bellflower (Campanula poscharskyana) if you don't mind it's tramping ways. This one also likes to be kept moist & fills any blank space. Blooms lavender-blue July-Oct. Bluestone says it's only 6", but mine are much taller on 2nd year plants -- more like 18" mounds with semi-trailing flowering stalks. Anytime it looks spent, I cut back, water with compost water (handful of compost in watering can overnight) or put the handful under the plant, then it reblooms.

Corrine

Good idea Corrine! I have that as well and it always performs really well. I also have the very similar Campanula portenschlagiana (dalmatian bellflower) which for me handles dry conditions better.

The serbian bellflower also has a yellow foliage version Campanula portenschlagiana Dickson's Gold, which is pretty. My friend alternates the green/gold versions in her bed and it looks very cool.

Germander is nice as an edger if you have full sun and can give it excellent drainage. As mentioned, there are many types of low growing campanulas (you might like blue clips). Blue carpet nepeta fills in quickly and blooms in the first year. Geranium "Bill Wallis" might fit the bill (pardon the pun).

Here is a link that might be useful: Geraniums at Annie's Annuals

Lavender is great for edging......if its hardy, but maybe salvia would work as well.
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I also use coreopsis for edging...stays tidy, looks good and blooms mid summer through frost.
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Also nepeta mussini is another great one that doesn't roam too far, but doesn't stay in bloom all summer.
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Another thought is some of the great short shrubs like spireas 'carpet series' which use foliage instead of flowering to give season long color.
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Flora

OOO I like that dianthus. How does one tell the longer blooming ones from the ones that give a short spring display? Are the cottage pinks longer blooming?

corrine and eightzoner - it's interesting to hear your experiences of Corydalis lutea and Campanula portenschlagiana as edging plants. Here they are both self sowers in stone walls and clearly enjoy moist conditions combined with extremely sharp drainage. I'm surprised C lutea copes with mulch around it. In my garden it grows straight out of stone steps.

I've shown these pix before but here they are again.

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zaphod42,

Love your screenname, by the way! Got your towel?

We are Douglas Adams fans too. Helps resolve all those questions about the meaning of life. :)

For the coreopsis, do you have to keep deadheading it? I just picked up "The Well Tended Perennial Garden" at the library and every perennial seems to need so much deadheading! I am going to try to get my sweet williams and foxgloves to last more than two years using her suggestions though.

You'd be deadheading all day and I find it was hard to tell the unopened buds from the buds that had finished blooming, as they are so small. It's a fast grower. I just sheared my Zagreb back this week. In the Fall, I will be digging the three plants up and dividing them again and transplaning them into smaller plants. I bet in another 2 yrs. I'll be repeating the procedure. I read that if you shear them back, they will rebloom, so we shall see. I made a notation the date they were sheared back so I can judge how long it takes to rebloom.