Many homeowners find it difficult to landscape shady areas.  The solution is in the selection of plants.   Some plants prefer shade, some will tolerate it and some won't do well at all.   Before you begin to landscape a shady area, you need to note exactly how much shade there is, what time of the day the area is shaded, and what causes the shade. A shady area is generally defined as one that receives less than 4 hours of sun a day year round.   Areas shaded by large trees are a special situation.  Determine how much light the site will receive in the winter before you choose your plants.  Another consideration is how plants will interact with tree roots and a heavy tree canopy as these items will cause dryness in the summer.  For example, Ericaceous plants such as Rhododendrons, Azaleas, Mountain Laurel and the like will not tolerate a dry shade such as that caused by a dense tree canopy or building overhangs.

Direction and Shade
Facing the sun at noon will give you south, with north behind you, east located to your left and west to the right.
 
Eastern exposure from sunrise to noon is considered perfect for a shade garden. Sunrise is the most gentle kind of light.

Northern exposure is light without direct sun, a lack of shadows and is often referred to as "artist light". This would be the second best place to create a shade garden.

Southern exposure will need something to create a screen from the sun such as trees, shrubs or other garden structures.  Sun will travel across the garden in this location and can be a good site for mixing some sun and shade plants together.

Western exposure is the least desirable spot for a shade garden as the sun in the afternoon will be too hot. 

Evergreens

Microbiota, Siberian Cypress
Taxus, Yew
Thuja, Arborvitae

Broadleaf Evergreens

Azalea, Azalea
Buxus, Boxwood
Euonymous,  Euonymous - Evergreen types except gold variegated forms
Ilex, Holly
Kalmia,  Mountain Laurel
Myrica, Bayberry
Pieris, Japanese Andromeda
Rhododendron, Rhododendron
Viburnum, Viburnum

Trees

Amelanchier, Serviceberry
Cercis, Eastern Redbud
Cornus, Dogwood
    *Cornus florida will tolerate part shade only because of anthracnose disease
Corylus,  Harry Lauder's Walking Stick
Tsuga canadensis, Canadian Hemlock

Deciduous Shrubs

Aronia, Chokeberry
Azalea Exbury, Exbury Azalea
Clethra, Sweet Pepper Bush
Hydrangea, Hydrangea, Snowball
Itea virginiana, Virginia Sweet Spire

Perennials

Aegopodium, Snow-on-the-Mountain/Bishop's Weed
Aquilegia, Columbine
Ajuga, Bugleweed
Aruncus, Goat's Beard
Asarum, European Ginger, Canadian Ginger
Astilbe, Feather Flower
Bergenia, Saxifrago
Brunnera, Alkanet / False Forget-Me-Not
Corydalis, Corydalis
Dicentra, Bleeding Hearts
Epimedium, Barrenwort
Ferns
Galium, Sweet Woodruff
Heuchera, Coral Bells
Heucherella, Foamy Bells
Hosta, Hosta, Plantain Lily
Houttuynia, Korean Houttuynia
Lamiastrum, Yellow Archangel
Lamium, Spotted Dead Nettle
Liriope, Lilyturf
Lobelia, Cardinal Flower
Mertensia, Virginia Bluebells
Primula, Primrose
Pulmonaria, Lungwort, Bethlehem Sage
Thalictrum, Meadow Rue
Tiarella, Foamflower
Tradescantia, Spiderwort
Tricyrtis, Japanese Toad Lilies

Annuals

Begonias
Browallia
Coleus
Fuschia
Impatiens
Lobelia
Torenia

Ground Covers

Ajuga, Bugleweed
Asarum, European Ginger, Canadian Ginger
Euonymous, Big Leaf Wintercreeper
Galium, Sweet Woodruff
Hedera helix, English Ivy
Houttuynia, Korean Houttuynia
Lamiastrum, Yellow Archangel
Lamium, Spotted Dead Nettle
Liriope, Lily Turf
Mazus,  Mazus
Pachysandra, Pachysandra, Japanese Spurge