Lungwort (Pulminaria) is low-growing, with spotted or veined and slightly hairy leaves and profuse beautiful blue, pink, white (or combination) clusters of flowers in spring. Hardy perenial in zone 6-- goes flat to the ground in winter, but new growth is early and vigorous. Will take full shade. Can be divided easily. Doesn't tolerate drought well, however. Should be front of the border.

Bleeding heart (dicentra) can grow into shrub size & has pink or white flowers. There are lots of types from low-growing "King of Hearts" to the shrubby sort of one, which I only know as "Old Fashioned". The Old Fashioned one is very easy to divide for propagation & flowers abundantly it the spring. Depending on its location, it recedes in my yard between June & September & comes back larger every year. Can be back of the border depending on how high of a border you want.

Pansies planted in the fall in the shade have bloomed for me starting mid-spring & going year-round without getting too leggy. Front of the border.

Sweet woodruff makes a pretty, scented ground cover with white flowers in the spring. It spreads easily. Doesn't tolerate drought. Just let it meander through everything (but not under hosta-- won't last there).

Native to PA plants: Trillium, Hepatica, Blue Cohosh, Blood Root, Virginia bluebells-- all ephemeral spring bloomers but with beautiful flowers can be planted front to mid-border & among other later, more lasting plants.

Good luck.

I'm a zone colder in the Lehigh valley.
I haven't tried too many of these yet as I'm just starting my shade garden this year, but things I have researched that will work (in addition to those mentioned already) are japonica pieris, a shrub with interesting spring blooms and varying heights depending on cultivar and Astilbe is a flowering shade perennial. you can also use begonias as an annual flower for color all summer. if you want another shrub, you can check out hydrangeas.

and I haven't been there yet but I've heard raves about Russell's Wholesale garden center (www.russellwholesale.com)
Good luck!

All of the previous ideas are good, but your bleeding hearts and Virginia bluebells, in particular, as mentioned above, will disappear by midsummer, so they are best paired with plants that do well midsummer into Fall, such as toad lilies. Toad Lilies seem to do quite well in well-drained PA clay.

I have found Hellebores (Lenten Roses) to be tough, persistent plants which bloom very early. They have large, dark, hand-shaped leaves and are upright enough to make a good backdrop for other things, like foamflowers.

Lily of the Valley is good for fragrance.

The Red Bud tree will tolerate some shade, but cast even more of it.

If you like Kerria, it is a fairly shade tolerant, bamboo-like shrub which has small, bright yellow flowers along the stems in Spring. It will spread outrageously in rich, moist soil, but in less advantageous positions it keeps to a reasonable size.

Oakleaf hydrangea also does very well in shade, as do, of course, rhododendrons and azaleas.

I would try rhododendrons and azeleas as evergreen and hydrangeas as late summer color shrub. Then fill the rest with various perennials as suggested. You will need to try them and see which ones will survive as every garden has its own micro climate. If your deck is not too high from the ground, you might be able to plant a climber to reach up to the deck railing, that would be pretty and once it climbs it will get more sun.

Dutchman's Pipe is somewhat shade tolerant, for a vine.