Challenges in the Shade
Sunlight offers challenges for your pavers, including bleaching them out so they don't stay true to their natural color. Shaded areas provide their own issues for your pavers as well. Water doesn't evaporate as quickly in shaded areas, which means your pavers must endure damp soil without eroding. The dark dampness also encourages growth of plants such as moss, which can grow on top of the pavers and make them slippery, in addition to hiding them from view. Dripping sap from trees above might enhance the slickness of your pavers.
Because of the consistent dampness often found in shaded areas, natural stone often makes a better paver for those areas than man-made products such as terra cotta and brick. When wet, these materials often begin to degrade or produce efflorescence, which is a white, powdery coating that mars the look. Stone such as granite and limestone work well in shaded areas, but avoid softer stone such as sandstone and slate. These can wear away quickly when consistently moist, cracking and chipping along the edges.
Shape It Up
Not all shapes are created equal when it comes to shady pathways. Rounded stones, such as cobblestone, don't work well in the shade. They become hard to walk on when it's damp, so keep them to sunny areas of your yard. Irregular shapes might leave large cracks between the stones, creating an ideal growing area for moss or other plants. Pavers with straight lines, such as cut granite, often work best because you can butt them closely together.
Keeping Plants Away
Some homeowners enjoy the look of moss, appreciating the Old-World feel it gives to paver pathways. However, moss can cover your stones over time and make them slippery to walk on. When you see moss growing between or on pavers, and you want to get rid of it, scrub it away with a stiff-bristled brush. Periodically adding about 2 parts bleach to 8 parts water can help keep the moss at bay. Grass isn't likely to grow well in heavy shade, but other plants, especially ground cover, might creep into your pathway. Pulling the plants as they encroach helps keep them under control, or you can spray unwanted plants with a non-selective herbicide such as one containing glyphosate.