I have been looking for some Rudbeckia hirta (Northern Black Eyed Susan ) for the house we bought out of forclosre last year here in Derry, NH. The klandscaping needed LOTS of work. CHAINSAW work!! But got it pretty under control now.

I planted 3 Rozanne geranium plants last summer, and have been pleased at the way they've taken off. They're in only partial sun but are blooming like crazy and I like their low sprawling habit. It's an informal look, for sure, but charming. Mine started later than some, mid to late July, and I hope they'll go for another few weeks.

For me, Rozanne will bloom up until frost. Moonbeam coreopsis blooms from June? July? to frost. It helps to shear off the spent tops after a big flush of bloom, but it is a fairly carefree plant.

I hope that interpreting 'perennial' loosely is OK. I have found Geranium 'Jolly Bee' is hardier than 'Rozanne', but both bloom all summer starting in early July. Type 3 clematis start blooming in early July and continue for at least a month, and for some varieties much more. I don't have all the names off the top of my head, but I know Ville de Lyon and Venosa Violacea bloom for more than 5 weeks. Clematis are vines, and type three clems get pruned to about a foot in late winter. My third plant is Hydrangea 'Endless Summer', which started blooming for me in early July and is still blooming. Like G. 'Jolly Bee' it will still be blooming (based on 4 years) when frost hits. I also have a coppery double mum that starts blooming in late August and will bloom through several hard frosts until the ground freezes or it's covered with snow, so it's often still blooming in mid-October, later than anything else in my garden.

Another vote for Rozanne. I purchased small plants last year and they are each 4x4 now and have been in constant bloom.

I love Catmint (Nepeta) because its purple flowers last a long time early in the season and its light foliage contrasts really well with other plants, including Coreopsis Zagreb (or Moonbeam), which are both nice long bloomers.

Another vote for catmint - I love it, and so do the bees!

For full sun I'm a big fan of Salvia ('Blue Hill' blooms for me from the start of June to mid- or end of August, 'East Friesland' about the same, just trying out 'Caradonna' this year), rose campion (mid-June to end of August), and Rudbeckia 'Indian Summer' (late June to end of September).

All three are drought tolerant, the rose campion and the Rudbeckia reseed nicely, and the Salvia takes division really well so you can quickly increase your stock. The rose campion does need deadheading to bloom this long. That's sort of a pain, but even if you leave the seedheads on it you still have the pale foliage providing some interest. (The Salvia need deadheading after their first main bloom too, but it's much easier to do.)

For part shade I have hydrangeas 'Annabelle' and 'White Dome', both of which bloom from late June until frost.

Thought I'd mention Yarrow (Achillea) which I grew from seed a few years ago. I'm really impressed with the longevity of its blooms...one month and still going!

Asclepias also blooms a long time. It keeps putting out new buds as old ones die off. I haven't been deadheading either. Probably if I did, I would get even more new buds.

Ruds. Particularly fond of:

"Indian Summer"
"Toto"
"Prairie (something...the one with the green cone)"

Not particularly fond of, but will allow in small amounts because they ARE pretty (they tend to flop all over the place):

Gloriosa Daisy

I love my tall, blue, balloon flowers.