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Tips for understanding shade

It may be the question most often asked by unhappy gardeners: “My yard is nothing but shade. What can I possibly do? Help!”

The hint of desperation in their tone is born from the mistaken belief that a shady yard—or a shady corner of a yard—is doomed to never hold a garden. In fact, a garden with light or dappled shade has an absolute wealth of plant choices available. Yards with medium to deep shade may face a somewhat more limited selection, but there are still plenty of plants from which to choose. It’s a rare spot that has so much shade that no ornamental plant will grow. Best of all, many plants will also bloom in a shady corner, and it’s the flowers that count for many gardeners.

That said, to find those shade-loving plants that will work best in your own “problem spot,” keep these factors in mind:

First, all shade is not created equal. At its simplest, shade falls into one of four categories: Light or partial shade is present when plants receive filtered but not direct sun or when areas get direct sun for only a couple of hours in early morning or late afternoon. This shade is where most shade-lovers do best. Darker-coloured plants tend to show off to best advantage here, too.

With full shade, plants receive no direct sun during the day but they do receive “reflected light.” This type of shade might be found under the canopy of a mature tree, or at the base of a north-facing wall. Some shade lovers that thrive in partial shade will also grow in full shade, but bloom time or plant size may be affected.

Deep shade is usually characterised by a continuous “dusk-like” quality, even during the height of day. Unfortunately, this is one of the most difficult areas in which to grow plants successfully. Heavy shade is an area that gets almost no direct light (under a low deck, for example). Very little will grow here successfully.

Second, if your shade is caused by trees or shrubs directly above where you wish to plant, be aware that research has shown that most of a tree’s root system exists in the top 2 feet of soil. That means that you would not only have to dig through these feeder roots to plant a shade garden (which will probably both stress your tree and aggravate you), any plants located there would have to compete with the tree for water and nutrients. Because the root system on a tree is so large, the tree is usually the winner in this sort of competition. Try to locate your garden as far away from the main trunks of any large tree as you can to avoid these problems. Since many shade plants enjoy the filtered light provided by tree canopies, you’re still in luck if you garden near trees.

Third, the sad truth is that almost all vegetables and even most herbs are sun-lovers. Very few do their best in a shady location. If your heart is set on raising veggies but your perfect garden site doesn’t get full sun, try planting bush varieties in containers and place the pots wherever you do get at least eight hours of sun, even if that means plopping a few pots on the front steps. As an alternative, you may find that most leafy vegetables (lettuce and the like) will tolerate more shade than other veggies.

So with tips in mind, check out a few of our favourite shady characters:

Dicentra spp.

(Light to medium shade)
A must-have for the shade garden, bleeding hearts offer fine-textured, ferny foliage and delicate, intriguing flowers. There are several different types—the old-fashioned bleeding heart has large flowers but it unfortunately goes dormant by midsummer. The fern-leafed types have smaller flowers but do bloom through the season.

The old-fashioned bleeding heart, D. spectabilis, grows to 5 feet and has chains of pink or white flowers. There are a number of fern-leafed types, in-cluding the cultivars ‘Bountiful’, which has pink flowers, ‘Bacchanal’, which blooms red, and ‘Aurora’, which is white. Also, in milder parts of the country, look for the yellow bleeding heart—D. scandens—a vine hardy in Zones 6 to 8.

Phlox spp.

(Light to medium shade)
Woodland phlox (P. divaricata) is native to woodland areas of North America. The plant stays small—reaching only a foot or so tall—and has lovely lavender-blue flowers in spring. It’s a great companion for other spring-blooming ground covers such as forget-me-nots.

There are a number of cultivars of woodland phlox available with flowers in shades of blue, lilac-blue, and nearly white.

Pulmonaria spp.

(Light shade)
Also known as lungworts, this group of plants with elegant silvery spotting on their leaves is one of my favourites for the border. Most have lovely blue flowers in early spring that soften to pink and last a surprisingly long time. After the flowers fade, you’re left with the wonderful variegated foliage that stays attractive through the rest of the season.

Convallaria spp.

(Light to heavy shade)
Commonly known as lily-of-the-valley, this old-fashioned perennial is one of the hardiest plants in the shade garden. Established clumps can go on for years with virtually no care. In spring, lily-of-the-valley sends up small shoots with white, bell-shaped flowers that are wonderfully fragrant. Lily-of-the-valley foliage is very attractive—the leaves are blue-green and oval-shaped. For a twist on the lily-of-the-valley, look for the cultivars ‘Rosea’, which has pink flowers, or ‘Albostriata’, which has white-striped leaves.

Two quick cautions here: Lily-of-the-valley can be aggressive, and must be watched carefully to keep it from overgrowing its location. All parts of the plant are also poisonous.

Tricyrtis spp.

(Light to medium shade)
Toad lilies are a late-blooming, overlooked shade plant. These perennials are good for adding height—they often stretch up to 3 feet tall in the garden. Their flowers, though somewhat lily-like, are often curiously spotted with purple, for an exotic look.

A number of cultivars are available that bloom in shades of purple, white, and even yellow. ‘Variegata’ has variegated foliage.

Helleborus spp.

(Light to medium shade)
Hellebores are often the first perennial to bloom in many gardens. If you look closely, you might see this plant’s resemblance to its cousins—the columbine and clematis. Hellebores have dark-green, leathery foliage that is evergreen in many areas. The flowers generally appear in shades of white, pink, green, and red, often before the snow has melted.

One of the hardiest species is H. orientalis, the Lenten rose. Another common hellebore is, the Christmas rose. Both are hardy to Zone 4. Hellebores are also poisonous.

Digitalis spp.

(Light to medium shade)
Another old-fashioned favourite, foxgloves have spikes of showy flowers in a range of colours from white to purple. The most common species, D. purpurea, is a biennial that self-seeds happily in many gardens, giving it the appearance of being a perennial.

Other perennial species of foxglove include D. grandiflora and D. lutea, both of which have yellow flowers and are hardy to Zone 3, and D. x mertonensis, which flowers pink.

Browallia spp.

(Light to medium shade)
This lovely annual, Browallia speciosa, bears many star-shaped blue flowers in summer and has appealing foliage. Browallias make great mates for some of the cooler-coloured impatiens, or stand well by themselves. The plants also perform well in baskets and containers. (For a stunning combination, combine them in containers with impatiens and trailing lobelia.)

Akebia spp.

(Light shade)
A relatively unknown vine, Akebia quinata (sometimes called chocolate vine on account of its fragrant flowers) has attractive foliage that may remind you of a tiny tropical umbrella tree. These hardy vines can become large—to 30 feet—and may engulf smaller structures in the garden if they’re not firmly anchored. Akebias bloom in early spring with purplish flower clusters that are commonly hidden by the foliage. These flowers give way to edible fruits.

Another species, A. trifoliata, is much like its cousin except it has leaves divided into three leaflets instead of five.

Cimicifuga spp.

(Light to medium shade)
Also known as bugbane, cimicifuga is a taller, late-blooming shade-garden gem that sends up spikes of white flowers. Some bugbanes have blooms that smell somewhat unpleasant; be sure not to plant these near your fragrant shade plants. When not in bloom, the plants have attractive astilbe-like foliage that in some cultivars is deep purplish-green.

Some of the purple-leafed cultivars are ‘Atropurpurea’ and ‘Brunette’. Both have plumes of white flowers and grow to about 4 feet.

Campanula spp.

(Light shade)
A large group of plants, campanulas (also known as bellflowers) have cup-like flowers in shades of blue or white. While not every campanula is well suited to the shade garden, low-growing C. poscharskyana, and its cousin C. medium, the biennial Canterbury bells, are both shade tolerant.

Aconitum spp.

(Light shade)
A relative of the delphinium, wolfsbane or monkshood (Aconitum spp.) has beautiful blue flowers and divided foliage. These flowers bloom in late summer or autumn, adding colour when the garden is short of blue flowers. The wind may tip over monkshood flower stalks if they are not planted in a protected spot. Stake the flowers to prevent this. Some well-known cultivars include ‘Bressingham Spire’, which has dark violet flowers, and ‘Bicolour’, with both blue and white flowers. (Note: Monkshoods are poisonous.)

Corydalis spp.

(Light to medium shade)
A group of plants related to the bleeding heart, most species of corydalis have beautiful, ferny foliage and clusters of flowers in shades of yellow, white, pink, red, purple, and blue. I’ve found C. lutea is one of the easiest shade-garden plants—it self-seeds in many gardens and blooms all season long, adding cheerful yellow flowers to the shady border.

Another corydalis that’s gotten a lot of attention is C. flexuosa—which has fragrant blue flowers in spring and sometimes again in autumn. It’s hardy in Zones 6 to 8.

Astilbe spp.

(Light to medium shade)
Must-haves for the moist shade garden, astilbes send up beautiful, feathery plumes in summer. The blooms range in colour from red to pink on into white and lavender. Height ranges from less than a foot to more than 5 feet tall. In addition to their attractive flowers, astilbes have divided foliage that’s often infused with reddish or bronzy tones.

Some nice cultivars include ‘Fanal’, with dark-red flowers, ‘Deutschland’, with white flowers, and ‘Rheinland’, with pink flowers.

Aquilegia spp.

(Light or medium shade)
Few plants are as graceful and distinct as the columbine. These relatives of monkshood and clematis bear odd, spurred flowers in summer. Their flowers appear in almost every shade, including white, black, and bi-colours. In addition, columbines have attractive fan-shaped foliage. Columbines are famous for self-seeding in the garden, though the seedlings from hybrids rarely look like their parents.

A. canadensis is a native columbine with red and yellow flowers. A. flabellata, the fan columbine, is a dwarf species with rich blue flowers and especially attractive blue-green foliage.

Liriope spp.

(Light to heavy shade)
When it’s not in bloom, some gardeners mistake lilyturf for an ornamental grass with its dark-green, grassy foliage. Spikes of purple or lavender flowers appear in summer. One of the best choices for highly shaded areas, liriope withstands a wide range of difficult conditions, including heat and drought.

Some white-flowering cultivars—including ‘Monroe White’, and some cultivars with variegated foliage (‘Variegata’), are particularly nice.

Geranium spp.

(Light shade)
True geraniums, not to be confused with their annual cousins (pelargoniums), are often overlooked in the shade garden. Most have attractive divided foliage and bloom in a wide range of colours—from nearly black to white. Some are ground covers, while others grow up to 2 feet.

One especially well-known cultivar is ‘Johnson’s Blue’, named for its blue summer flowers. One of the longest-blooming species is G. sanguineum, which also has foliage that turns colour in autumn.

Iris spp.

(Light shade)
While many gardeners are most familiar with the showy, fragrant flowers of tall bearded irises, some gems in this group native to woodlands are wonderful additions to the shade garden. Siberian irises, I. siberica, can take a small amount of shade, as well, especially in hot climates.

Myosotis spp.

(Light to medium shade)
Forget-me-not is a prized ground cover in the shade and it has flowers in a rare shade of blue. A biennial, this plant self-seeds readily in many gardens and can become a pest if left unchecked. Given that, it’s still well worth growing for its lovely springtime flowers. For added variety, look for white- and pink-flowering cultivars such as ‘Snowball’ or ‘Victoria Rose’.

Primula spp.

(Light shade)
Primroses lend an English garden feeling to any area with their clusters of colourful flowers and flat, hairy leaves. Several hundred different species of these plants exist, and hundreds of hybrids on top of that; the colour range is nearly endless. Many of the shade-loving species prefer a slightly acidic soil that has plenty of organic matter. The flower typically known as the “florist’s primrose” can be grown outside. Primroses like cooler summers and may not do well in areas where temperatures rise dramatically.

Trillium spp.

(Light to medium shade)
Sometimes called wakerobins for their very early bloom time, trilliums are woodland plants with three showy petals in shades of red, white, and yellow. The plants send up three leaves in the spring—and these are the only leaves the plants have for the season. White-flowered T. grandiflorum is the most common garden trillium.

Aristolochia spp.

(Light shade)
Calico flower produces one of the most distinctive flowers in the shade garden. These vines usually have heart-shaped foliage and pipe-shaped flowers in shades of white, green, and purple. The plants can become quite large—place them well to prevent any structures from collapsing. The hardiest type, A. macrophylla, has dark-green, heart-shaped leaves and small greenish flowers that often hide in the foliage.

Loosestrifes range from ground covers to upright perennials.

Loosestrifes range from ground covers to upright perennials. Many make good cut flowers. Most types have clusters of yellow or white flowers arranged in tall spikes.

Plant facts

  • Common name: Loosestrife
  • Botanical name: Lysimachia spp.
  • Zones: 3 to 9, depending on species
  • Height: To 4 feet tall, depending on species
  • From: Areas of Europe, Asia, and North America
  • Family: Primulaceae (primrose family)

Growing conditions

  • Sun: Full sun or partial shade
  • Soil: Moist, well-drained soils are best, but the plants adapt to many types of moist soil.
  • Moisture: Keep soil evenly moist.

Care

  • Mulch: A layer of mulch around the base of the plant will help keep weeds at bay. Mulch also helps conserve moisture and keeps soil temperatures consistent.
  • Pruning: Cut plants back in autumn after they freeze or in spring before they begin to grow.
  • Fertiliser: In average soil, no fertiliser is necessary.
  • Propagation
  • Division: Divide loosestrifes in spring or autumn.

Pests

  • Leaf spot: In summer or autumn, leaves develop yellow to brown spots, often with concentric rings that form a bull’s-eye pattern. To deter leaf spot, prune the plant to allow good airflow and avoid wetting the foliage in afternoons and evenings.

Garden notes

  • While not aggressive weeds, some loosestrifes can grow quickly in the garden. Root guards may help prevent spreading; leave some space between loosestrifes and plants that don’t grow as quickly.
  • Don’t confuse these loosestrifes (Lysimachia spp.) with the invasive purple loosestrife (Lythrum spp.).

Selections

  • Lysimachia ciliata: Grows to 4 feet tall with yellow flowers in summer. This species can get quite aggressive. Zones 3 to 9. Native to areas of North America.
  • Lysimachia clethroides: Grows to 3 feet tall with spikes of white flowers in summer. This species can get quite aggressive. Good for cutting. Zones 4 to 9.
  • Lysimachia clethroides ‘Geisha’: Grows to 3 feet tall with leaves edged in creamy yellow and spikes of summer-blooming white flowers. Grows much slower than the species. Good for cutting. Zones 4 to 9.
  • Lysimachia nummularia: Aggressive ground cover with yellow flowers in summer. Grows to 4 inches tall. Zones 4 to 8.
  • Lysimachia punctata: Grows to 3 feet tall with spikes of yellow flowers in summer. This species can get quite aggressive. Zones 3 to 9.
  • Lysimachia punctata ‘Alexander’: This selection grows to 3 feet tall with leaves edged in white and spikes of summer-blooming yellow flowers. Grows slower than the species. Zones 3 to 9.

Wisteria

Even if you don’t live in a region where wisteria is hardy, you’re probably familiar with these lovely fast-growing vines. The plants are known for their hanging clusters of pink, purple, white, or blue pea like flowers. Flowers are fragrant and give way to pods of seeds.

Plant facts

Common name: Wisteria
Botanical name: Wisteria spp.
Zones: 4 to 9, depending on species
Size: Climb to 30 feet or more
From: Areas of Asia and North America, depending on species
Family: Fabaceae, the pea family

Growing conditions

Sun: Plant wisteria in full sun with at least 6 hours of direct sun each day.

Soil: The soil must remain moist and well drained. If soil is high in sand or clay, amend it with organic matter before planting. The more organic matter, the better.

Moisture: Water wisteria in times of drought.

Care

Mulch: Place a layer of mulch around the base of the plant to keep weeds at bay, conserve moisture, and maintain consistent soil temperatures. Leave a 4-inch gap between the mulch and the wisteria’s trunk.

Pruning: Pruning keeps these large vines in check. To encourage flowering shoots, cut the newest side shoots back about 6 inches from the main branch in midsummer. In winter, prune the regrowth back to about three nodes (leaves) from their main branch. This will help encourage the growth of flowering shoots in spring.

Fertiliser: In average soil, wisteria doesn’t require fertilisation. Too much fertiliser can inhibit blooms.

Support: These vines need a sturdy structure for support because they can easily reach 30 feet or more.

Propagation

Seed: Soak seeds in warm water for 24 to 36 hours. Plant them outdoors in a sheltered spot in the garden or in a moist seed-starting mix. Germination can take a month or more. Wisteria started from seed can take many years to bloom and may be inferior plants compared to cultivars.

Cuttings: Take softwood cuttings in spring or early summer. Cuttings root in about eight weeks.

Layering: Bend one of the growing shoots toward the ground in early spring. Remove the leaves along a section of the stem, gently nick the stem in that area, then bury that section under several inches of soil. Anchor the shoot to the ground. The stem should root in about a year. After it roots, cut it from the mother plant.

Pests

Aphids: These small insects often appear in large numbers on new growth. Spray them off daily with a stream of water; they will not attack a plant after being knocked off. Use an insecticidal soap or neem-oil spray if infestations are severe.

Japanese beetles: These large, dark-coloured beetles chew holes in leaves. If infestations are severe, try an insecticide made from neem. Immature Japanese beetles are white grubs that eat plant roots. To reduce the number of grubs, use a grub killer or a bacterium called milky spore.

Leaf-miners: Leaf-miners are small flies. Their larvae burrow tunnels in plant leaves. In most cases, the damage affects only the look of the plant, not the plant’s health. Remove and destroy any infected leaves. Keep a layer of mulch around the plant to help prevent leaf-miners from burrowing into the soil, where they pupate and become adult flies.

Scale insects: Scale insects look like tiny disks on plant stems or roots. They suck juices from plant cells. Encourage beneficial insects, such as wasps, or use horticultural oil.

Viruses: A few viruses can infect wisteria. They often cause a decrease in vigour, malformed new growth, and a mosaic pattern of discolouration on leaves. Unfortunately, once a plant is infected with a virus, there’s no saving it-it’s best to destroy the plant.

Fungal disease: Fungal diseases occur when the plant is in a spot that’s too wet. Once a plant is infected with a fungal disease, there’s little you can do to stop the disease. To prevent fungal diseases, prune vines to encourage good airflow, plant wisteria in well-drained soil, and keep the foliage dry. Prune infected leaves or branches to help keep the disease from spreading. Destroy any infected leaves that fall to the ground.

Leaf spot: Many leaf spotting diseases appear as discoloured spots on leaf surfaces made up of concentric circles, forming a tiny bull’s-eye pattern.
Powdery mildew: This disease first appears as discoloured spots on plant leaves. As it progresses, the leaves become covered with a grey powder and drop off.

Garden notes

• Most parts of the wisteria plant, especially the seeds, are poisonous to people and animals.
• Some types of wisteria (Wisteria floribunda and W. sinensis) are considered invasive in certain parts of the country. Check with local authorities before planting a wisteria.
• Wisteria vines cannot climb walls-they need an arbor, trellis, flagpole, or similar structure for support.

Some gardeners try to train their wisterias as standards, or trees. This takes intensive pruning, as well as a very sturdy stake for the vine’s “trunk.”