How about some of the shorter daylilies? 'Little Grapette' has been mentioned on another thread. I believe it stays in the 18-20" range (including scapes). There are lots of others that fall in the under 20" category. They only bloom 2-3 weeks, however.

Huechera 'Fire Fly' blooms continuously from June through mid-August for me in 4-6 hours of full sun (heavily mulched in organic soil).

Tricia

Achillea 'Moonshine' is still blooming after beginning in late May. Foliage is nice too. Coreopsis Moonbeam is low and a long bloomer. Nice filler plant with delicate leaves that don't crowd other plants. Gaillardia Goblin blooms a long time but doesn't always return every spring. Taking a break from all that yellow, salvia May Night blooms all summer if you keep deadheading.

You don't say anything about color, but you might consider Dwarf Platycodon - Balloon Flower. Mine started in the spring and they're still blooming - very pretty little purple balloon shaped flowers, and the dwarf variety doesn't get any taller than about 8", if that. Mine has expanded nicely during the past several years and it's a very prolific bloomer. One of my favorites for the front of the border.

I also like Oenthera - Sun Drops - bright yellow flowers on maroon colored stems with narrow dark green leaves. I've read that it can be invasive in warmer zones, but in zone 5, I haven't found it to be invasive at all.

And, of course, there's Nepeta Walker's low - silvery green leaves with pretty purple flowers - starts in the spring and blooms most of the summer...gets no taller than about 10".

Heucheras would also be nice - there are many variations to choose from.

Sounds like a pretty garden - you'll have to post some pictures so we can see!

Ooops - sorry, forgot to mention color scheme and what I don't want.

My beds have blooms in shades of pink (cool pinks, no warm pinks), purples/blues, and white (no creams - yea, I know I'm fussy). So want something in those color ranges.

Have lots of balloon flower already, so that's out. Also have lots of coral bells already (man, did I OD on the coral bells this season...my poor Visa is still yelping). I'm not a daylily fan.

Good suggestions, though, keep 'em coming! :)

Here's a suggestion that really does not fit in with your color scheme but that I like namely Mrs. Bradshaw. Tough little low-water plant with bright little red flowers. 24" tall by 18" wide. I love this guy. In my experience needs lots of sun.

Kate

Here is a link that might be useful: Geum 'Mrs. Bradshaw'

I'd go to Google, and look at the various cultivars of Delosperma. It's Hardy Iceplant, and a terrific low-growing succulent-type plant which comes in many colors, ranging from hot to cool pinks and purples. Many of the cultivars are only hardy to zone 6, but there's at least one, Delosperma 'Kelaidis' which is good to zone 4. It's salmon pink in color. These things bloom from May to September, but they close up at night. They look good before and after the bloom period, as well. They're self-cleaning, and spread slowly but steadily. Very drought tolerant. Almost a perfect plant.

Here's my patch of D. cooperi, grown from seed 3 years ago:

{{gwi:252762}}

It was several 2" clumps when I planted it out, and now I keep it trimmed back to a 6' diameter patch. The photo was taken last month, and it's even more densely covered with blossoms now. 6" tall at it's highest point.

I wintersowed Dianthus barbatus last year and this year they bloomed May, June, July and looks like they'll bloom again. They started in mid-May and are still going. The colors would look nice against the rose and lambs ear also. You could follow them with dwarf Shasta's if you want white, or maybe Monarda Petite Delight for a bright pink. To take it all the way to the end of fall, the dwarf container dahlias, - http://www.containerdahlias.com - and mums are the best. My dahlias bloomed into November till the 2nd hard freeze last year.

The dianthus are in the foreground

{{gwi:252763}}

Veronica "Royal Candles" and Scabiosa "Butterfly Blue" keep blooming all summer. Also the dark leafed sedums, while not actually in bloom are a dark purple that could fit in. I grow "Purple Emperor".

I'll recommend Scabiosa too. I have Butterfly Blue and it blooms all summer. There's two smaller varieties - Blue Diamonds and Ritz Blue. Both of mine are babies so I don't know if they flower as much as Butterfly Blue. There's a pink variety too but I don't grow that one.

How about boltonia asteroides 'nana'. Nice little daisy (white-lavendar color)type flowers that for me blooms for about 8 weeks starting in mid-June. Stays 12-14" high.

Veronica Red Fox has a long bloom period if you deadhead and how about Tunic Flower (Tunica Saxifragia) It starts blooming mid June and keeps going almost all summer. It's only a few inches high, pink baby's breath type flowers, wants good drainage, should be hardy for you. In my zone 4 garden it's borderline, but I've only lost 3 or 4 in 10 years growing it. Can be difficult to find, Bluestone usually carries it. It doesn't look like much the first summer, but by the 2nd it's going beautifully.

Look into Dianthus. Firewitch and Tiny Rubies have both been in bloom for me since late May. The flowers are sporadic now, but the mat forming foliage is a very nice blue/green. Many sedums would also give you a nice bluish/pinkish color all summer with pink to rose flowers late in summer. I have Bertrum Anderson and Vera Jamison whose foliage color is a big plus in my garden now, even without flowers. Both of these suggestions would add a texture interest to your present plantings.

I second dianthus. I have 3 of Telstar Picotee and they bloom all summer, after a VERY floriferous spring flush.

I am totally loving these two:

Cosmos Dwarf Red (I'm pretty sure it's "Cosmic Red" but could also be "Ladybird" More likely Cosmic, as I recall from the tag)- it loves to be deadheaded, and blooms profusely! It's going & going! Gets about 10-12"

Gaillardia- I'm sorry I don't know which variety this is, but it's a tight clump former, and COVERED with blooms. It, too, just keeps going & going.

Both of these have been blooming since mid-June for me.

And although they are 'boring' to many a gardener, I simply LOVE a marigold! I put in a whole circle of "Colossus" this year (from seed), and they are just getting started blooming, but I expect them to last til frost. There are a thousand varieties of these (my personal favorites are the mid-height poofy varieties), but they last & last!

Good luck!

I love my Campanula carpatica "White Clips" and "Blue Clips" - they always bloom for a nice long time for me. Coreopsis "Moonbeam" is also a long bloomer. I also have Potentilla "Miss Wilmott" that blooms for a long time, can get a bit leggy though and likes to weave.

tess

Agastache, Agastache! Xeriscape, a hummer magnet, various colors (the blues didn't do a thing for me and were not long bloomers....look at the other colors...the pinks are radiant and there are orange/peachy shades now)Blooms in mid July straight to frost with absolutely NO deadheading...the flowers just "stay". (maybe one light shear in Sept/Oct?) Compact, bushy and no maintenance. The only thing you MUST do is to provide sandy loam that is well, well drained and a full sun (preferably in winter too) location. It's very adaptable to more water during the season but a soggy soil in winter will take it down. Mine thrive here! Golden Jubilee is another winner. Chartreause/lime foliage with blue flowers. Google and you'll see some great images. Fragrant as well.

My Geranium 'Phaeum' was very long blooming and is a fantastic foliage plant too, keeps such a nice neat mound shape with pretty leaves.
The flowers are nothing to write home about and mine is in shade a lot of the time, but maybe someone else can comment on other cultivars and their sun tolerance (I think they're fine) and length of flowering.
Teucrium fruticans is another work horse with purpley magenta flowers and a new one for me which is flowering still now in winter here is statice - Limonium perezii. Great leaves and purple flowers.
Regards
Susie

There is a salvia cultivar called 'Marcus' that stays very short... 8 to 10 inches tall if I remember correctly, but google that to make sure.

DIANTHUS!!!!
there are so many pretty ones to choose from, even doubles, I think they are so cute and I love the foliage color and the way it matts up like a carpet.
BTW- that ice plant is gorgeous! Mine is the yellow kind and I don't really care for it.
I was going to say mini roses, but you already have roses, but you could always have more. John's miniature roses has a lot of really pretty ones.( You should check out their website) Some produce blooms as tiny as a dime. I think they are cute, and they bloom all summer, and come back every year! Just a thought! -Jessica

My Salvia 'Marcus' stays fairly short (about 10" - 12") and blooms all summer with deadheading.

Blackswampgirl - where did you get your S. Marcus? Mine died last year and I meant to replace it - nice little plant.
Alyricss

My favorite edger is Armeria maratima. Great grassy foliage, long season of bloom, excellent edger. And, it's pink.

Dianthus bloom season is very variable; I love the cottage pinks, D. plumarius, for their silvery foliage. Sometimes the clumps die back horribly, maybe once every 5 years, in an "undisturbed" (untended) area; this seems to happen after an especially spectacular bloom period.

I just read about Salvia 'Sensation Rose' which is supposedly a sister plant to Salvia Marcus -- short, compact, long-blooming.

I found them in a local garden center this weekend... well it wasn't SOOOOOOOO local... about an hour away, but I knew they would have it, addict that I am.... and they did!

I have two S. Marcus's in my holding area, that I never had the right place to put them. Now I am going to put the two Marcus'es and the 3 new S. Sensation Roses together in a nice little group.

A nice white long-blooming dianthus with silver foliage would round out my new little grouping just nicely... if there is such a thing. Maybe snow in summer...

Wendyb, white Dianthus?

there's Dianthus "aqua"

{{gwi:252764}}

or how about Dianthus arenarius

{{gwi:252766}}

or Dianthus "Charles Musgrave"

{{gwi:252767}}

Dianthus "her majesty"

{{gwi:252768}}

Dianthus "Margret Curtis"

{{gwi:252769}}

Dianthus "Mrs. Simpkin"

{{gwi:252770}}

All of these are available at Joycreek nursery (joycreek.com). I don't grow these but I got my Dianthus "rose de mai" 7 years ago from Joycreek and it's a wonderful plant.

I really like Campanula 'Samantha.' It's a lavender-blue with a white eye. The only problem is that my camera can't get the color right, so I have no good photos of it. This plant is a little blooming machine, even in part shade. It blooms all summer, & last year bloomed until the middle of October. It's about a foot tall & is fragrant.