Often times in shaded areas the soil is damp and compacted. Add peatmoss to your soil that will help aerate your soil. Also, add some season-long fertilizer, such as Osmocote, and always water with root stimulator. If you have moss growing in those areas, kill off the moss with a moss killer prior to planting. Perennials for shade Astilbes - Elegant, beautiful perennials that grow well in shade.
Flowers come in white, pink, red, and lavender spikes.
Cimicifuga - A dramatic tall plant with attractive foliage and white fall flowers. Tiariella - A spreading woodland ground cover undemanding and easy to grow. White, foamy flowers in late spring. Gold striped foliage will add color and texture Convallaria - Lily of the Valley. Attractive shade ground cover.