The first thing to keep in mind is that plants living in shade behave differently from those living in the sun. Trying to design in a formal manner will pretty much be a frustrating experience. Formality is balanced and controlled, and sun is a prerequisite for this look. Instead, look to nature for inspiration on how to combine randomness, asymmetry, and lots of green textures without bright colors or definitively shaped plants. My rule of thumb is that 80 percent of a shade-garden plant list should be composed of a handful of plants that are happy to be there and will fight each other to take over. A mentor once advised this exercise: After making an initial plant list, eliminate half and double the remaining. This applies to most of garden plant selection, but it is especially helpful to achieving success in shade gardening.
First, study the forms and characters of the plants that already exist in the shade area. What are they? What needs to be removed to expose the bones of what is most pleasing? When designing for shade or natural/native areas, design is often as much about managing and revealing as it is about adding.
Think in Layers
Shade typically involves trees. When deciding how to plant underneath them, think about understory planting as a series of layers. Visualize how each layer fits and interacts with the one above it. Remember that every plant added creates more shade for those below it. Among the layers, tallest are the understory trees (these are smaller trees that live in the dappled light cast by taller trees); then shrubs; next groundcovers and perennials; and finally the ground-hugging ephemerals or bulbs. After I’ve evaluated what exists and taken out what I don’t want, I look at the “negative spaces” that surround the canopies and shapes I’ve chosen to work with. New additions will fill these negative spaces, so it is important to choose plants with forms and growth habits that fit comfortably within and underneath the skeleton pieces. The first layer I add is the understory trees. These often add the interest of blooms or fruit.
It’s important that these first additions respect the context into which they will be fitting, from both a survival and an aesthetic standpoint. In the nursery, I look for imperfect plants; the stamped-from-a-mold, uniform-looking, carefully groomed plant will look out of place the moment it is added to a shade garden. As it acclimates and loses the fullness it had from growing up in a full-sun nursery, it will look sickly. I tend to choose irregular, multistemmed, loose specimens that will immediately look at home in a shady context.
Plant in Large Groupings or Drifts
The shrub layer is planted next. I look for shrubs that won’t overfill the negative spaces but rather complement and add texture and contrast. Shrubs will thin out once transplanted into shade. To plan for this, I often plant them in groupings and in a variety of sizes. I like shrubs that lose their clearly defined shape over time and grow together into a larger mass. Once things blend together nicely, you can add some accents to spice it up.
I suggest the same approach for the perennial and ground plane layer, which is the most challenging because of all the root competition and rivalry for light and water. Consequently, planting large masses and strong drifts of plants that are happy to be in deep shade will yield the best result. Personally, I prefer to have healthy, rather pedestrian perennials that prosper rather than a “circus dog” perennial that fights to survive and constantly needs fussing over.
It’s About Texture, Not Color
Pick plants that vary in leaf size and texture rather than worry about blooms or bloom color. Shades of green and bold leaf textures and contrasts are pleasing to the eye. Gardens with too much of the same textures tend to look weedy, flat, and uninspiring. My favorite gardens are successful and interesting even if none of the plants bloom!
Shade plants look most natural when their forms are loose, and not too formal or symmetrical.