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Many gardeners love to be outside in their garden on a nice sunny summer afternoon. But what if your garden is in a spot where it is in full sun and the air temperature is 35 degrees with a heat index of over 38 degrees? Enough for fun, right?
But what if your garden is in a location that is 20 degrees cooler that same afternoon and doesn’t require sunscreen? Shade gardens offer opportunities to grow plants that don’t thrive in locations with more sunlight, and they also offer opportunities to enjoy gardening more on warmer days.
As the number of hot days in Greater Columbus increases and the climate changes, the need for shade in urban environments increases, even in our gardens.
Define shadow
Shade can vary in intensity and it is important to understand the level of shade in a particular location if you expect plants to thrive in a shade garden. The following definitions can help a gardener choose the right plants for each location based on the amount of sun or shade a particular location receives.
Full sun Locations are locations that receive six or more hours of direct sunlight per day. This does not have to be continuous, as a location may receive four hours of sun in the morning, shade in the middle of the day, and three or four hours of sun in the afternoon. Full sun locations should receive direct, full sunlight.
Partly sunny locations receive between four and six hours of sunlight each day.
Partial shade locations receive two to four hours of sun per day. Partially shaded locations often receive filtered or dappled sun, as do locations under exposed trees, such as pagoda and birch, which produce a constantly moving pattern of sun and shade.
Moderate shade locations receive less than two hours of sunlight per day. Often these types of locations receive mostly reflected light, such as on the floor of a hardwood forest.
Heavy shadow locations that do not receive direct sunlight, such as the base of a north wall or under dense evergreen trees. Few plants will grow in the most severe shade conditions, as all plants need some light to grow and thrive.
Gardening with shade
Many urban and suburban residential lots have limited sunlight due to proximity to other homes or an overabundance of trees. In these locations, the best way for a gardener to deal with this is to embrace the shade and choose plants that thrive in the shade.
Shade-tolerant plants tend to have thin leaves with large surface areas. These plants are anatomically adapted to be efficient at photosynthesis in low light. Being more sensitive to light reduces their ability to withstand direct sunlight for extended periods of time.
These plants can generally tolerate some early morning sunlight, but exposure to sunlight throughout the day can cause the leaves to bleach and develop burn marks and scorch the leaf edges.
Keep in mind that the amount and location of shade on a residential lot can change dramatically over time as existing trees mature and new trees are added to the landscape.
When I moved to my home in Columbus 13 years ago, the only shade on my large lot was under a mature maple tree. After planting a few dozen trees over the years, I now have several shady spots where I once planted sun-loving plants, but where shade-tolerant plants now thrive.
Perennials for shade
Herbaceous perennials are great choices for creating an attractive shade garden with plants that will return year after year. Select a variety of species that bloom at different times of the year to provide color all season long.
Some perennials that are good choices for partially to heavily shaded locations include: the bleeding heart (Lamprocapnos spectabilis), black snake root (Actaea racemose), red whortleberry (Actaea rubra), lady’s mantle (Alchemilla mollis), astilbe (Astilbe species.), Japanese painted fern (Athyrium niponicumvar. Pictum), heart-leaved brunnera (Brunnera macrophylla), hosta (hosta species), creeping phlox (Phlox stolonifera), Jacob’s ladder (Polemonium green bean) and others.
Annuals provide color in the shade
Adding annual flowers to a shade garden is a great way to add color. Flowering annuals that can be grown in shady areas include wax begonia (Begonia x semperflorens cultorum), impatience (Busy Lizzie), lobelia (Lobelia erinus), coleus (Solenostemon scutellarioides), polka dot plant (Hypoestes phyllostachya) and violet (Viola X wittrockiana).
Shrubs provide height and structure
Adding a few woody ornamental shrubs to a shade garden can add height and structure to the garden, as most perennials and annuals suitable for shaded areas are less than 18 inches tall.
Woody shrubs do best in partial shade locations that receive two to four hours of sunlight per day. Shrubs that can be grown in shady locations include fothergilla (Fothergilla species.), oakleaf hydrangea (Hydrangea quercifolia), smooth hydrangea (Hydrangea arborescens), tree of life (Thuja species) and others.
I recently added two red dogwoods (Cornus species.) to one of my shade gardens for visual interest in winter and they seem to do fine, although the color of the stems (red and yellow) may not be as vibrant as when they are in full sun.
Diversify plantings
Consider incorporating other types of plants into your shade garden. Ferns are one type of plant that does well in shady areas. Some native Ohio ferns that can be incorporated into a shade garden include lady fern (Athyrium filix-femina), ostrich fern (Matteuccia struthiopteris) which does well in moist, shady places and cinnamon fern (Osmundastrum cinnamomeum) with its tall, arching leaves.
Some native Ohio wildflowers thrive in shady spots, so consider adding some of these plants, including the wild columbine (Columbine canadensis), wild geranium (Spotted stork’s bill) and crested iris (Iris cristata).
And because you want a cool, shady spot to sit and read a book on a hot day, be sure to add a walking path or stepping stones to your new favorite garden spot, along with a garden bench or chair.
Mike Hogan is an Extension Educator, Agriculture and Natural Resources and Associate Professor at The Ohio State University Extension.
