It is natural for most plants to strive for sunshine, but there are shade loving perennials that can't tolerate full sun.
There is no clear definition of shade; it can range from slight to dense shady conditions. Most perennials like several hours of morning sunlight, but the heat of the noon is too hot for them.
Such plants usually survive in any conditions except direct sunlight in the hottest part of the day, or growing in the deepest shade.
For the shade areas of your garden we would recommend to choose Hosta, Foxglove, Solomons Seal, Foamflower, Blue Star Amsonia, Dog Bane, Meadow-rue, Lungwort, Forget-me-not, Lily of the Valley and Coral Bells.
For especially shady locations that receive very little sunlight, like the ones under the trees, ferns would be more than suitable. It is a well-known fact that ferns will survive in places which are considered too dark for many plants. There are lots of fern varieties you can choose from, and a combination of a few different species would be beautiful and original. Keep it in mind that some of fern varieties die off in the fall but here are also evergreen varieties for all year round.
Lungwort plants are great shade loving perennials that usually prefer areas with partial shade. They will decorate your garden with tender pink or blue flowers and their unusual foliage with whitish silver spots.
Bluestar Amsonia is another perennial shade flower that likes shady conditions. As it's implied from its name, the flowers of this perennial are blue and star shaped. They look especially charming if planted in groups. The blooming period will cover May to June, but the green leaves will decorate your garden till the end of summer.
Lenten Rose or Christmas Rose is an excellent plant. They are rather effortless to take care of provided you do not disturb them by trying to move or divide the plants. They come in different colours.
Hosta (plantain lilies) plant is a very popular choice for shade gardens. There are a wide range of varieties with different leaf textures, colors and sizes. The foliage is not the only attraction; they have beautiful flowers and will bloom from the end of spring and all through the summer months.