I just bought a "Jolly Bee" which is supposed to be as good as Rozanne. Time will tell!

Though I don't have Rozanne to compare it to, Jolly Bee is incredible for the length of bloom. It bloomed forever, even past a couple of killing frosts, to late October here in zone 3/4, last year. It is growing at a tremendous rate after surviving a very hard winter.

Patricia is another very long bloomer, a good 2 1/2 months for me, and has a very intense purple flower with a black eye. Very striking.

Geranium pratense (?) striatum, a groundcover with light pink flowers and deeper pink veins, blooms heavily in early summer and off and on all season.

Kate

Yes, I know two other very long bloomers (apart from Rozanne and Patricia), but I'm afraid they are not as cold hardy as you would like them to !
They are G. x riversleianum cultivars : Russel Pritchard and Mavis Simpson...In full sun, from early may until frost, here...

And, by the way, as far as I know, 'Jolly Bee' is a twin to 'Rozanne'...you can't differentiate one from the other when you plant them side by side ! (just as G. x renardii 'Philippe Vapelle' and 'Terre Franche'!). Marketing, marketing...
Unless our specialists here can explain the differences...they sure have better eyes than me ! lol...