FLOWERS FOR THE SUMMER SHADE GARDEN

The pretty pink flowers of Japanese anemone seem to glow in the shade.

Shade in the garden can come in many forms – the terms full, part, dappled, filtered, light and deep are often used to describe it. In fact, a single property could have all of the above in varying degrees throughout the day. Time is also a critical factor, as morning shade followed by full sun in the afternoon could negate the benefit of the morning shade.

One of the best ways to gain a better understanding of your shade conditions is to perform a garden audit. Start with a scaled plan that accurately locates elements that contribute to shade, such as the residence, garage, walls, fences, vegetation and neighboring buildings. Indicate the various shade zones, types and duration. Note any measures that could improve the shade/light conditions (e.g. pruning) and the performance of various plants in the different shade zones.

A tidy border of hostas is edged with colorful lamiums.

Your audit should also indicate if it’s dry shade (usually the result of shallow tree roots and fast-draining soils) or moist shade (usually the result of less-than-perfect drainage). Knowing the wind direction and soil conditions is essential for recognizing the implications to plant health and soil fertility and drainage.

Shade Bloomer Characteristics

Shade-tolerant plants often have large, dark, glossy foliage to trap available light for photosynthesis. In many instances, foliage dominates over flowers. Flower color usually includes lighter pinks, creams, lavenders and blues, which are less conspicuous than the brighter colors of sun-loving border plants. Also, plants growing in shade may bloom later and have fewer flowers than plants of the same species that receive more sunlight.

White and lavender barrenwort flowers lend a delicate touch to the shade garden.

Fortunately for the shade gardener, there are some telltale signs that indicate when shade-blooming plants are struggling. Often, they’ll lean toward the light, be smaller in stature and have smaller leaves and fewer flowers than expected. Self-propagation by seed or root spread may be limited, and in the worst case the plants may disappear. If this happens, there are remedial steps you can take. Remove seed heads to direct more of the plant’s energy into developing stronger roots. Also, prune overhead trees and shrubs to let in more light. Amend and fortify nutrient-deficient soils with compost and manure. Finally, consider new and improved cultivars of favored species developed specifically for shade.

The dark reddish-purple flowers of Angelica gigas and the rich yellow flowers of Ligularia make a stunning combination in the shade.

Many outstanding summer-flowering shade plants originated in Japan. One of the best known is Japanese kerria (Kerria japonica), with its many double and multi-petal varieties. Its yellow flowers start in June and can repeatedly bloom throughout the summer. It has striking green stems that add interest throughout the winter. Other popular contributions include cone-shaped flowering hydrangeas (Hydrangea paniculata) and white-and-pink flowered Japanese climbing hydrangea vine (Schizophragma hydrangeoides ‘Moonlight’and 'Roseum’), which can be complemented by native oakleaf hydrangea (Hydrangea quercifolia). It features oak-like foliage and white flower clusters throughout the summer.

The delicate pale-blue flowers of false hydrangea seem to float above the foliage.

Two Japanese shade-tolerant perennials I couldn't live without are upright ginger (Saruma henryi) and yellow wax bells (Kirengeshoma palmata). Both have arching stems to 1m and soft-yellow flowers. Upright ginger will grow in almost full shade and may repeatedly bloom throughout the summer and into the fall. Yellow wax bells have light-green, maple-shaped foliage and display yellow flowers throughout late summer. Other attractive summer-blooming shade-garden perennials from Japan include false anemone (Anemonopsis macrophylla), an elegant 70cm tall plant with downward-facing, parasol-shaped lavender flowers, white-flowered two-lobed false hydrangea (Deinanthe bifida) and silky, violet-colored Japanese wood poppy (Glaucidium palmatum).

In addition to the many fine Asian species, there are other shade-loving plants that deserve special mention for their beauty and adaptability. Green and gold (Chrysogonum virginianum) is a non-invasive native groundcover with buttery yellow flowers and spade-shaped leaves. It blooms in my garden (zone 6) in early May, but can repeat bloom later in the summer. It’s often used as a woodland path edger. A second favorite is the perennial begonia (Begonia grandis), which flowers repeatedly throughout the summer in heavy to partial shade and dampish but not waterlogged soil. Its red stems and undersides of its heart-shaped foliage make a striking display.

A repeat bloomer throughout July and August is Indian pink (Spigelia marilandica). Native to the southeastern United States, it has multiple red, upright, tube-shaped flowers that open at their ends to expose what looks like a second smaller bright-yellow, star-shaped flower. This clump-forming plant stands erect to about 70cm.

The papery flowers of masterwort are backlit by a chartreuse hosta.

The many cultivars of Masterwort (Astrantia major) produce clustered flowers surrounded by showy bracts in pink, red and whitish-green hues from June through September. These erect (50cm – 90cm) clump-forming plants mix well with other shade lovers or can stand on their own as accents. They prefer a compost-amended soil with good moisture-holding abilities.

Bleeding hearts, particularly cultivars of Dicentra eximia and formosa, offer long-lasting, repeat-blooming flowers in the summer shade garden. While more compact than the larger Dicentra spectabilis types, they have proved dependable and persistent in the summer heat. Their ferny, deeply-cut foliage complements white, cherry-pink and raspberry-red flowers, depending on the selected cultivar. These attractive plants add a romantic air and make desirable edging plants for the shady border.

False anemone bears delicate racemes of nodding lavender-pink flowers in late summer that contrast nicely with bolder leaved plants.

Lastly, various late-summer-blooming cyclamens such as Cyclamen hederifolium and purpurascens produce attractive heart-shaped foliage and striking butterfly-winged reflex-shaped petals. Over the years in well-drained shady soils, they can bulk up and produce tens of flowers. I like to use them to edge the sides of shady paths.

The summer shade garden doesn’t need to be relegated to only colorful foliage plants. There are many showy flowering plants that can light up the shade garden, making it a more diversified and interesting landscape.

Text by Frank Kershaw

Photos by Marnie Wright

Frank Kershaw is an award-winning horticulturist with more than 40 years of experience.

Marnie Wright is a lifelong gardener, writer and passionate garden photographer. Her Rocksborough Garden, developed over 30 years, is located in Bracebridge, Ontario.