All hardy to at least USDA zone 5, some hardier.
Blue Wild Indigo - Baptisia australis
Valued for pea-shaped flowers in early summer and for bluish green foliage the rest of the season. Plants usually grow to four feet high and wide after three seasons in the garden.
Lesser Calamint - Calamintha nepeta ssp. Nepetoides
It grows in a tidy clump that is only 18 inches high, yet it blooms in the late summer into fall. The tiny flowers are white early in its bloom period, but intensify to pale lavender-blue in the fall.
Baneberry - Cimicifuga simplex ‘Brunette’
One of the first of several dark-foliage Cimicifuga cultivars, ‘Brunette’ has proved to be classy, reliable and fragrant. The purple foliage stays low and attractive and the white bottlebrush-like flowers grow to 4 or 5 feet tall, coming into bloom in early fall.
Cranesbill - Geranium macrorrhizum
It spreads quickly enough to be a ground cover, but slowly enough so that you’ll never curse its presence in your landscape. There are several named varieties with pale pink to fuchsia colored flowers, and all plants grow to about 15 inches high. One of the few plants that tolerate dry shade, G. macrorrhizum blooms in June and looks attractive after bloom.
Catmint - Nepeta x faassenii ‘Six Hills Giant’
‘Six Hills Giant’ is a lovely lavender-blooming plant that looks good no matter how you treat it. You can leave it as is all summer, cut the stems in half in early July to stimulate more growth and flowers, or cut it to the ground to make room for late-summer annuals. This Nepeta gets two to three feet tall and wide and is the perfect plant to combine with ornamental grasses.
Yellow Waxbells - Kirengeshoma palmata
Yellow waxbells is a large plant, and is best planted singly as a specimen. Large maple-like leaves appear in early summer followed in late summer by pale yellow bell-shaped flowers that continue to bloom over a six-week period. Like Baptesia, this plant does not transplant well so place it appropriately. Plant Kirengeshoma at least four feet from any other large plant or passageway….I learned the hard way and now I have to move a stone path in order to accommodate a plant that has matured to five feet tall and five feet wide.