Gaillardias bloom all summer. Helenium 'Double Trouble' is a sterile hybrid Helenium that blooms a very long time. Coreopsis 'Creme Br�l�e' blooms most of June and July here. Russian Sage blooms all summer too.

Instead of eliminating such great plants from your list, I'd try to find out why such strong perennials won't grow for you.

Clematis (type 3 pruning) will bloom in summer, as will Hydrangea paniculatas like Limelight, PinkyWinky, Pink Diamond, etc, Hydrangea arborescens like Annabelle or Incrediball, etc, or the reblooming Hydrangea macrophyllas like Twist and Shout, Penny Mac, Endless Summer, etc. Elderberry is another summer blooming shrub and there are a lot of long-blooming roses.

Many of the campanulas bloom in summer as do many of the long-blooming Geraniums like Rosanne or Jolly Bee, among others. Tall Phlox blooms in summer here along with many daylilies. Some of the self-seeding biennials like foxglove and Lychnis coronaria (AKA rose campion.) Lily bulbs and other summer blooming bulbs like a few of the aliums and Galanthus Summer Snowflake will add flowers to the season.

Also, with the right choice of foliage, you don't need to be staring at just "greenery" for months since you can have a beautiful garden with contrasting foliage, texture, and color. Here are a few photos where the focus is on the foliage with the flowers being just the icing on the cake.
{{gwi:226218}}From June 2010

{{gwi:226220}}From June 2010

{{gwi:226222}}From June 2010

{{gwi:226225}}From June 2010

Careful with that last example of pretty greenery. That grass, called ribbon grass, call be very invasive. We're digging it out right now. In other news, if anyone wants to trade for it, I've got plenty!

The best thing that you can do to fill blooming gaps is to drive around your neighborhood when nothing is blooming in your garden, see what's blooming elsewhere, then put it into your yard. As Maniac points out, if things are blooming elsewhere that you already have in your yard, there's something wrong.

I see you're in zone 7. I wonder if alstroemeria would bloom all summer for you. It does here in Michigan, but I know it prefers cooler weather, so may shut down and stay just green in hotter climates during the summer.

Coreopsis, especially the new ones bred by former Epimedium man Darrell Probst; Salvias, the western ones with names like 'Ultra Violet', 'Black Cherry', sold by High Country Gardens; Agastaches of any type; Pardancandas; Geraniums 'Rozanne', 'Dilys'. Most of these plants will bloom until frost.

I depend on foliage a lot. Coral Bells, Coleus are my focus for Aug to frost. I am not so much on waiting for flowers. I throw some Zinna seeds and I am good to go for the summer.

Daylilies are probably the most popular summer-blooming perennial. Other long-blooming summer perennials include: Coreopsis (if deadheaded), Ice Plant or Delosperma, Pincushion Flower or Scabiosa (if deadheaded), Shasta Daisy (if deadheaded), Gallardia, Salvia, Chrysogonum virginianum or Green & Gold, Potentilla (deciduous shrub form), Platycodon or Balloon Flower (if deadheaded), butterfly weed or Asclepias Tuberosa, Geranium sanguineum, Kniphofia Uvaria or Red-Hot Poker, Oneothera missouriensis or Ozark Sundrops, Gaura lindheimeri. That's just to name some of the better known ones.

As others have mentioned, coneflowers are as tough as they get so if you cannot grow them, you will struggle with others. I would test your soil and see what is going on before investing in other stuff.

emmi331,

What happened to your coneflowers, poppies, yarrow, and bee balm. With the exception of poppies (which I don't have experience with), those flowers are pretty hardy. We may want to find out why they died before we recommend anything.

Paul

Emmi, I am curious what has happened with your Echinacea and bee balm? Both of these are usually durable, vigorous perennials.

My front garden has many showy ornamentals blooming now like Peonies, Foxglove, Irises, and Columbine. The back garden, which consists of mostly native perennials, blooms best in July and August. Monarda, Phlox, Cardinal flower, Echinacea, Heliopsis, Rudbeckia, Silphium, Asters, Cimicifuga and more bloom in the summer.

This year it may be earlier because we seem to be 2-3 weeks ahead of normal schedule!

I also grow a lot of annuals amongst the perennials with large patches in back and they start going strong in July/August and bloom till frost.

Thanks to all for your wonderful suggestions! I suspect one reason some flowers do badly is my soil isn't deep enough for their roots to really dig in. I've been building it up and amending it (it was terrible soil when I moved into this house) for years. Oddly, though, other tall flowers like campion and goldenrod have done very well. So have bright yellow primroses, and day lilies, too. Coneflowers don't work ANY place in my yard - they are sad-looking, droopy, colorless, and don't spread. They look like they have the flu, in other words. Eventually they simply don't come back. This is not a big garden, and I'm not an uber-dedicated gardener, so if I find something that isn't fussy, it stays there and we're both happy. Just haven't found unfussy stuff for July yet. But I am listing your suggestions, and trying some!
Yes, I do have lovely foliage - the pale and spidery campion, bright mint, and so on. Thanks for the pics, nhbabs, to remind me how pretty leaves & stems can be.

Just to clarify, the ribbon grass is in an old clay chimney tile set set slightly above grade so its foliage can mingle with other plants, but it doesn't escape.

{{gwi:226228}}

Heliopsis: blooms last a long time.

Betty