Astilbe: Many varieties. Low growers of 8 inches to 2 foot blooms. Flowers are large fluffy plumes in shades of white, red, pink, salmon. Blooms in mid to late summer. Striking. Partial sun to open shade.
Bleeding Heart: These are great spring bloomers and mine perform even in my deepest shade. They die back in mid to late summer here.
Bugbane: Grows large- 3 to 4 ft tall. Gets bushy. Very, very fragrant white bottle-brush shaped flower plumes in late summer, fall. Repels insects. Deep roots. Partial sun, mine does ok in dappled shade with only a few hours of sun.
Columbine: Depending on variety, flower stems get 10” to 2 feet tall above foliage. Star-shaped bell-like flowers can be found in red, red and yellow, blue and white, all white etc. Likes dappled shade. Flowers sporadically through season, most in spring.
Cordyalis: (Related to the Bleeding Hearts)
Blue Panda: Lacey clumps of foliage put out lots of small, narrow electric-blue flowers. Sweetly fragrant. Really lovely. Requires good drainage, mine are in open to part shade. Bloom profusely all season. These hybrids can bloom themselves to death, sometimes you need to force them to rest by preventing bloom by lopping off the new buds for a month, a season or so. Generally prevent bloom after Sept. always. No or light fertilizer. Don’t mulch near roots. Sandy soil helps drainage.
Yellow cordyalis: Much less fussy than Blue Panda, these have no soil or light requirements. Supposedly will grow anywhere except in the soggy places. Same flowers, but yellow. Grow prolifically, bloom prolifically. Will self-seed. Invasive in zone 7, not in zone 5.
Cyclamen, Hardy: Low growers, like dry shade. Flat bulbs. Bright pink flowers and leaves show up in late summer/fall. Leaves are supposed to live all winter then die back in spring.
Daylilies: Will tolerate more shade than most people think.
Ferns of all kinds: Japanese painted fern is especially nice with its maroon and grey-green fronds. Likes organic matter in the soil.
Foxglove (digitalis): Shade partial sun. Tall spikes of flowers in several shades. Biennial.
Garden Phlox: Tall, 4-5 feet. Straight growing, leaves look weed-like. Nice in large mass. Bright flower clumps in white, pink, red. Self seed all over. Get raggedy but very colorful. Partial sun. Attracts humming birds.
Helleborus: (Christmas Rose-white, Lenten Rose-pink). Dark glossy leaves in groups of 5, evergreen. Very early bloomers (February-April) the blooms turn green as seed pods grow, mine still have them. Form bush-like mounds 12-15” tall, slower to get established. Nice winter color. Full shade.
Hostas: There are a many vareties with lovely foliage. Some have very fragrant blossoms too. However, the blooms are not their primary feature - it's their foliage. Many varieties. Grow in leafy clumps which slowly spread.
Iris cristata: This is a short (3-5 inches) clumping and spreading iris. It is usually lavender, you can find white. It requires decent drainage. This stuff has performed exceedingly well for me giving dense mats of color in spring.
Jacob’s ladder: About a foot-18”. Fern-like green and yellow foliage. Tiny blue flowers in spring.
Lamium: Invasive shade ground cover. Low growing. Small leaves look frosted with white stripe. Can get yellow-leaved varieties. Flowers in spring, various colors available. Full shade. Good for filling in under trees where nothing else will grow, but hard to get rid of once established.
Lily-Of-The-Valley (): Sweet scented white blooms in spring. 6-8 inches, broad upright leaves. Can spread quickly forming clumps. Full shade, cool moist spots.
Pink Lily-Of-The-Valley: Many times pink Lily-Of-The-Valley is not as invasive as the white.
Monarda (bee balm): Tall, can be weedy-looking like the garden phlox. Bright red flower heads. Butterflies and hummingbirds like them. Best in masses. Spread quickly. Partial sun-shade.
Pachysandra: Evergreen dark green ground cover. Deep shade to partial sun. Inconsequential white flowers in spring. Spreads well.
Pagoda lilies: Early spring woodlands flowers from a tuber. Yellow lilly shaped flowers about 2 inxches across on and 12-18 inch stem followed by broad low leaves. The plant disappears as the summer wears on.
Pulmonaria: 8-12 inches. Dark green leaves with attractive white spots. Small dark violet flowers in spring. There are also white and pink varieties.
Phlox Stoloniferus (sp?): A woodlands variety of phlox, partial to light shade. Flowers in pink, blue, or white on 8 inch stems in spring. Creeping ground cover.
Stargazer lilies (oriental hybrides): Will often get by with a few hours of sun a day and dappled shade part of the day.
Toad lily: Shade to full sun. Can get 2 or so ft tall, smooth green leaves. Small (1-2 inch across) orchid-like flowers. White with speckles, lavender. Blooms in late summer, fall. Hardy in zone 6 (CT)
Vinca (myrtle): Evergreen viney ground cover, dark green leaves, nice little blue flowers in spring. Shade to part sun. Spreads well.