Garden: Gardening in the shade

Many gardeners love being outside in their garden on a beautiful sunny summer afternoon. But what if your garden is in a full-sun location and the air temperature is 95 degrees with a heat index of more than 100 degrees? So much for fun, right?

But what if your garden was in a location that was 20 degrees cooler on that same afternoon and required no application of sunscreen? Shade gardens offer opportunities to grow plants that will not thrive in locations with higher levels of sunlight, and they also offer opportunities for more enjoyment of gardening on days with higher temperatures.

As the number of high heat days has grown in Greater Columbus with a changing climate, the need for shade is increasing in urban environments, even in our gardens.

Defining shade

Shade can vary in intensity and it is important to understand the level of shade in a particular location if you expect plants in a shade garden to thrive. The following definitions may help a gardener choose the correct plants for any location based on the amount of sun or shade received in a particular location.

Full-sun locations are those which receive six or more hours of direct sunlight per day. This doesn’t need to be continuous, as a location might receive four hours of sun in the morning, shade during the middle of the day and three or four hours of sun in the afternoon. Full-sun locations must receive direct, full sun.

Partial-sun locations receive between four and six hours of sun each day.

Partial-shade locations receive two to four hours of sun each day. Locations with partial shade often receive filtered or dappled sun, such as locations under open canopied trees, such as honey locust and birch, which produce an ever-moving pattern of sun and shade.

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Moderate-shade locations receive less than two hours of sun each day. Many times, these types of locations receive mostly reflected light, such as on the floor of a hardwood forest.

Heavy-shade locations receive no direct sunlight, such as the base of a north-facing wall or below dense evergreen trees. Few plants will grow in the heaviest 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 the proximity of other homes or an abundance of trees. In these types of locations, the best way for a gardener to cope is to embrace the shade and choose plants which thrive in shade.

Shade-tolerant plants typically 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 typically tolerate some sun in the early morning, but exposure to sun throughout the day will cause their foliage to become bleached and marked with burn spots and their leaf margins to become scorched.

It should be noted that over time, the amount and location of shade on a residential property can change dramatically as existing trees mature and new trees are added to the landscape.

When I moved to my Columbus home 13 years ago, the only shade on my large lot was beneath a mature maple. After planting a couple dozen trees over the years, I now have several shady areas where I once planted sun-loving plants, but now shade-tolerant plants thrive.

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Perennials for shade

Herbaceous perennials are great choices for creating an attractive shade garden with plants that come back year after year. Select a variety of species which bloom at different times of the year to provide season-long color.

Some perennials which are good choices for partially to heavily shaded locations include the following: bleeding heart (Lamprocapnos spectabilis), black snakeroot (Actaea racemose), red baneberry (Actaea rubra), lady’s mantle (Alchemilla mollis), astilbe (Astilbe spp.), Japanese painted fern (Athyrium niponicumvar. Pictum), heartleaf brunnera (Brunnera macrophylla), hosta (hosta spp.), creeping phlox (Phlox stolonifera), Jacob's ladder (Polemonium caeruleum) and others.

Annuals add color in shade

Including annual flowers in a shade garden is a great way to add color. Flowering annuals which can be grown in shaded areas include wax begonia (Begonia x semperflorens cultorum), impatiens (Impatiens walleriana), lobelia (Lobelia erinus), coleus (Solenostemon scutellarioides), polka dot plant (Hypoestes phyllostachya) and pansy (Viola X wittrockiana).

Shrubs provide height and structure

Adding a few woody ornamental shrubs to a shade garden is a great way to give height and structure to the garden as most perennials and annuals adapted to shaded locations tend to be shorter than 18 inches tall.

Woody shrubs do best in partial-shade locations, which receive two to four hours of sunlight each day. Shrubs which can be grown in shaded locations include fothergilla (Fothergilla spp.), oakleaf hydrangea (Hydrangea quercifolia), smooth hydrangea (Hydrangea arborescens), arborvitae (Thuja spp.) and others.

I recently added two red twig dogwoods (Cornus spp.) to one of my shade gardens for visual interest during winter and they seem to be thriving, although the color of the stems (red and yellow) may not be as vibrant as when they are grown in full sun.

Diversify plantings

Consider incorporating other types of plants in your shade garden. Ferns are a type of plant which do well in shaded locations. Some native Ohio ferns which can be incorporated into a shade garden include lady fern (Athyrium filix-femina), ostrich fern (Matteuccia struthiopteris) which does well in wet shaded locations and cinnamon fern (Osmundastrum cinnamomeum) with its tall, arching fronds.

Some native Ohio wildflowers thrive in shaded locations, so consider adding some of these plants including wild columbine (Aquilegia canadensis), wild geranium (Geranium maculatum) and crested iris (Iris cristata).

And because you will want a cool shaded location to sit and read a book on a hot day, be sure to incorporate a walking path or stepping stones along with a garden bench or chair in your new favorite garden space.

Mike Hogan is Extension Educator, Agriculture and Natural Resources and associate professor with Ohio State University Extension.

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This article originally appeared on The Columbus Dispatch: Garden: Shade gardens have benefits for some plants