Connecticut Garden Journal: When planning shade gardens, consider light and moisture levels
Winter is a good time of year to plan some new gardens. One area that always puzzles gardeners is shade. Finding the right perennial flowers to grow in the shade can be challenging. That's mostly because all shade isn't created equal.
The first step is to determine the type of shade you have. Part shade means that at some point there is sun on that area during the day. It could be a few hours in the morning or afternoon. Dappled shade usually refers to light filtered through tree leaves so the light is dappled on the flowers beneath. Deep shade is where no direct light reaches. This is often under an evergreen tree or on the north side of a house. Of course, there are varying degrees to all these designations. We had a house where the north side didn't receive any direct light. But there was enough indirect light and open space around it that we still grew ferns and hostas.
Another factor is moisture. If the area has sandy or rocky soil, you should select plants good for dry shade. These include euphorbia, brunnera, lamium, hardy geranium and epimedium. These will thrive under the dry conditions. If your area has wet soils, choose plants that are adapted such as Soloman's seal, ferns, astilbe, cardinal flower and great blue lobelia.
Don't grow perennial flowers under a low hanging, evergreen tree such as spruce. For limbed up, large deciduous trees, such as oaks, plant away from the trunk so the flowers have fewer large roots to compete with and more light to grow.