Our
Garden Gang's
Perennial
Shade Gardens
As we drool over catalogs
containing pages of colorful flowers – the problem is that most of these
plants require full sun. That's a rare commodity for most of us who
have small lots shaded by walls, trees and shrubs. Even gardeners fortunate
enough to have large open spaces find many shady nooks and corners just
crying out for cultivation. The fact that impatiens and begonias
consistently rank among the five most popular annuals sold each year is
evidence of this shady problem faced by most North American
gardeners.
Yet
there are alternatives to these standard bedding plants. In fact, with a
little planning, your shade garden can be as beautiful and interesting as
your sun-filled garden. Here, we'll discuss basic techniques of shade
gardening, including types of shade, methods for reducing shade, soil
preparation, and maintenance. Next, we'll cover a selection of
perennials for shady gardens.
Jump
straight to the best perennials for shade, or read on to learn about
the different types of shade and ways to deal with them. Also see our
chart of the best perennial ground covers for
Dry Shade.
Types
of Shade
First
and foremost, all shade is not created equal. Areas with partial shade allow
for a broad range of interesting and colorful plants, while deep shade,
particularly dry, deep shade, such as that found under a massive oak or pine
trees, severely limits the number of plants that will thrive. Understanding
the type of shade you have and choosing plants for those particular light
requirements is the single most important element of a successful shade
garden.
Dappled
shade is created by a light canopy of tree foliage, a pergola, or
a lath roof. A moving pattern of sunlight and shade across the ground
provides direct sun for one or two hours a day, and the area receives
bright, indirect light during the rest of the day. A wide range of plants,
including woodland plants, will thrive in dappled shade. Not all trees
produce dappled shade; evergreens and trees with dense foliage create deep
shade.
Light
shade is often referred to as open shade, because the area is
open to the sky, but walls, hedges, or other structures block direct
sunlight. Even though there is no direct sun, the area still receives plenty
of reflected bright light. Many plants will thrive in light shade, including
vines and climbers that can be used to cover stark, unattractive walls and
privacy fences. The soil in these spaces tends to be dry, as much of the
rainfall is blocked by the structures.
Generally,
partial shade is defined as an area that
receives two to six hours of sun each day. Many plants that prefer full sun
will perform well in partial shade.
Deep
shade can be defined as an area that receives no direct sun, and
has low light intensity throughout most of the day. These types of
conditions can be found under an evergreen or in a recessed entryway.
Although the number of plants that will grow in deep shade is small, a few
will actually thrive in it.
Shady
areas along streams, ponds, or well-watered flowerbeds are moist
shade areas. Shade loving plants that require consistently moist
soil, such as maidenhair and cinnamon ferns, trillium, bluebells, and
forget-me-nots, will thrive in these areas.
Dry
shade, such as the kind found under oak and eucalyptus trees,
presents the biggest challenge for the shade gardener, as few plants
tolerate both shade and dry soil. The trees rob most of the nutrients and
water from surrounding plants, and their complex root systems make soil
amendment difficult.
Reducing
Shade
It
is possible to reduce deep shade to dappled shade under trees and large
shrubs by pruning. Thinning out branches
opens up the canopy, allowing more light to reach the ground and increasing
air circulation. The tree on the right shows the "before"
look, and the one below left shows a properly thinned out "after"
look.
Just as you would with roses, start by removing dead or diseased branches
first. Then prune those that grow toward the center of the tree or shrub,
rather than outward. Continue pruning selectively, until you achieve the
desired amount of shade.
Never
prune more than one-third of the branches in one year. Try to remove small
branches rather than major limbs. Removing the lowest branches will
raise the tree’s canopy and permit more direct sun to reach the ground.
Another
option is the complete removal of large shrubs and trees, particularly if
they are planted too closely together. This may be the only option in the
case of trees or shrubs that drop leaves which are toxic to most plants,
such as the eucalyptus or black walnut.
Use
paint and mirrors to add light.
Walls and privacy fences that form the perimeter of a shady nook can be
brightened by painting them white; this will reflect available light and
visually brighten the entire area.
Another
technique used by ardent shade gardeners is the placement of mirrors on the
garden walls. Mirrors reflect light and create an illusion of depth, a
particularly useful trick in small gardens. The mirror should be suitable
for outdoor use; select heavy plate glass with a waterproof back. It should
have pre-drilled holes allowing it to be mounted to the wall using brass
screws, which are buffered with plastic or rubber washers. Framing the
mirror with a false-perspective trellis, false doorframe, or stone arch will
create an illusion that the garden continues on beyond the wall.
Soil
Preparation, Fertilizing and Spacing
While
proper soil preparation is vital for any type of garden, the soil in shade
gardens often has even more deficiencies than soil found in open, sunny
spaces. Trees, hedges, and shrubs rob much of the moisture and nutrients
from surrounding soil. Walls and fences deflect rainwater, resulting in dry
soil. A thick build-up of damp leaves in woodland areas can promote fungal
diseases and infestations of slugs and snails.
Poor,
dry soil found in front of walls is best corrected by double
digging, which means digging the flowerbed to twice the depth of
the spade’s blade. Remove the soil and place it in a wheelbarrow or on a
plastic tarp next to the planting bed. Then spread a thick layer of organic
matter (i.e., compost, leaf mold, or peat) in the bottom of the trench,
which will not only enrich the soil, but aid in moisture retention. As you
replace the garden soil back into the trench, work in generous amounts of
organic matter. Add fertilizer to the top layer (ten to twelve inches) of
soil.
Double
digging is not only difficult, but most likely impossible, underneath trees
due to their extensive root systems. The only option may be to loosen and
amend the soil in small pockets, to a minimum diameter and depth that is
twice the size of the plant’s root ball. Where possible, choose plants
with shallow root systems that won’t compete with the roots of the tree.
Adding
organic matter to the soil will help it retain moisture, but
plantings in competition with large shrubs and trees may require more
frequent watering than other parts of the lawn. Plantings under eaves or in
front of walls may also require additional water. Spreading a two-inch layer
of lightweight, organic mulch around the plants will help retain
moisture. Other areas of the shade garden will require less frequent
watering, as the lack of direct sunlight reduces the rate of evaporation. A
good rule of thumb is to water until it has penetrated four or five inches
of soil. Allow the soil to dry out slightly before watering
again.
Shade
plants need regular fertilizing, but
their metabolism is slower than that of sun-loving plants, so choose a mild
fertilizer, such as a fish emulsion mixture. Of course, azaleas, camellias
and rhododendrons use a special fertilizer made just for these acid-loving
plants.
Shade-loving
plants are generally more sensitive to spacing
requirements than sun-loving plants. Planting too closely in a moist, shady
environment reduces air circulation and promotes fungal diseases, such as
powdery mildew. For the same reason, don’t allow decaying leaf litter,
large pieces of bark, and other garden debris to clutter up the shade
garden. Removal of this garden debris will also reduce the number of hiding
places for slugs and snails.
So
now that the basics are out of the way, it’s time for the fun part
Perennials
for Shade
African
Blue Lily (Agapanthus). Light shade to full sun, zones 6-10.
Both deciduous and evergreen varieties are available. Agapanthus forms large
clumps of strap-shaped leaves with rounded umbels of blue or white flowers
growing on tall stalks. Water frequently when the plant is in bloom; remove
flower stalks after blooms fade. Performs best in normal garden soil, but
tolerates some clay.
Astilbe
(Astilbe). Light to dense shade, zones 4-8.
Astilbe has tall plumes of white, red, or pink flowers that rise above
glossy, dark green foliage. The plant prefers cool, moist, humus-rich soil,
although it cannot tolerate wet winters without adequate drainage. Astilbe
is a heavy feeder and can deplete the soil as years pass, so fertilize
regularly.
Barrenwort
(Epimedium). Light shade to dense shade, zones 5-9.
Barrenwort bears small, orchid-like or saucer-shaped flowers in red, pink,
purple, yellow, or white from spring to early summer. The leathery,
heart-shaped leaves often turn a bronze color in the autumn. Most species
reach 12” tall. It prefers fertile, humus-rich, moist soil in shade, with
shelter from cold, dry winds. For the best display of foliage and flowers,
clip back old leaves in late winter or early spring before flower spikes
emerge (the exception to this is E. perralderianum).
Bear’s
Breeches (Acanthus mollis). Light shade to full sun, zones 7-10.
This striking, vertical plant has large, dark green leaves up to 36” long
with tall, white and purple flower spikes reaching 3’ tall or higher.
Although Bear’s breech prefers moist, fertile, loamy soil, it will
tolerate dry, sandy soil. Remove fading flower stalks. This plant’s
spreading root system can be invasive.
Bellflower
(Campanula). Light shade to full sun, zones 3-8.
Many varieties of Campanula will perform well in light shade, such as C.
alliariifolia (Ivory Bells), C. americana, C. ‘Burghaltii’, C. collina,
C. ‘Elizabeth’, C. glomerata (Clustered Bellflower), and C. lactiflora
(Milky bellflower). The bell shaped flowers are usually pink, blue,
lavender, purple or white, and bloom from late spring to late summer. Most
species prefer fertile, neutral to alkaline, moist soil. The delicate flower
colors are best preserved in the shade. Tall species require staking. Cut
back after flowering to encourage a second flush of flowers. Campanulas will
self-seed given favorable conditions.
Bethlehem
Sage (Pulmonaria saccharata). Light shade to dense shade, zones
4-8.
The plant’s dark green leaves are speckled with patches of white and form
rosettes that grow 6-8” high. In spring, clusters of blue or white flowers
appear on stalks 10-12” tall. Bethlehem sage prefers moist, humus-rich
soil and requires little maintenance. Water during dry periods.
Bleeding
Heart (Dicentra). Light shade to full sun, zones 4-8.
Bleeding heart has pendent, heart-shaped flowers in a variety of colors and
attractive, fern-like foliage. It will self-sow if growing conditions are
favorable, and most hybrids prefer moist, humus-rich soil, although D.
chrysantha needs a dry, sunny site. Ingesting the plant can cause stomach
upset. D. spectabilis (Bleeding Heart) blooms profusely in spring and then
goes dormant in midsummer. D. eximia (Fringed Bleeding Heart) does not have
a dormancy period, blooming in spring (although less abundantly than D.
eximia) and then intermittently into autumn.
Bugbane
(Cimicifuga) Light shade, zones 3-8.
From June to August, bugbane produces bottle-brush spires of white flowers
that can rise as much as 8 feet above the foliage clumps, which can reach 3
feet. Native to woodlands, bugbane prefers moist, humus-rich soil.
Cardinal
Flower (Lobelia
cardinalis). Light shade to full sun, zones 3-9.
The cardinal flower bears tall spikes of bright red flowers from midsummer
to fall. Although short-lived, it will self-sow where conditions are
favorable. Cardinal flowers prefer moist, well-drained sandy loam that is
humus-rich. Water frequently and mulch heavily to retain moisture if the
plant is exposed to direct sun.
Chinese
Foxglove (Rehmannia
elata). Light shade, zones 9-10.
From spring to autumn, Rehmannia elata bears tubular pink flowers similar in
shape to foxglove blossoms. The pendent flowers hang from branching stems,
which can reach to five feet. Water freely during the growing season, and
grow in moderately fertile, humus-rich soil. Where not hardy, lift roots
before the first fall frost and pot up, overwintering in a cool, dry place
where temperatures remain above 45 degrees.
Columbine
(Aquilegia). Light
shade to full sun, zones 3-9.
Delicate, spurred flowers in a variety of colors rise on tall stalks from 18”
to 36” above light green, notched, compound leaves. Columbine prefers
better than adequate drainage and needs cool, moist, humus-rich soil. It
tolerates full sun only in cool climates.
Coral
Flower (Heuchera).
Light shade, zones 3-8 (with the exception of H.versicolor for zones
8-10 and H. villosa for zones 5-9).
Several
small, tubular flowers in a variety of colors appear on tall stalks rising
from mounds of heart-shaped, deeply veined, sometimes marbled leaves. Plant
heights range from 12” to 30”, depending upon the species. Grow in
fertile, moist, neutral soil. The woody rootstock grows upward; eventually
the plant must be lifted and replanted in late summer or early autumn, with
just the crown above the surface.
Creeping
Phlox (Phlox adsurgens). Light shade
to full sun, zones 4-8.
This creeping, semi-evergreen perennial is covered with a carpet of small,
pink flowers in late spring and early summer. The plant reaches a height and
spread of 12”. It prefers fertile, humus-rich, moist soil.
Daylily
(Hemerocallis). Light shade to full sun, zones 3-10.
Daylily flowers come in a variety of colors and most types bloom for a
period of three to four weeks, although several new hybrids have been
cultivated to bloom all summer long, such as the Stella d’ Oro daylily.
Some cultivars are evergreen in mild climates. Daylilies prefer average,
well-drained, humus-rich soil. Too much fertilizer causes lush growth of
foliage at the expense of the flowers. Hot sun can cause the flowers to fade
prematurely; provide direct sun only in cooler climates. Deadhead to
maintain a neat appearance.
Elephant’s
Ears (Bergenia). Light shade to
dense shade, zones 3-8.
Clusters of small, funnel-shaped, red, pink, or white flowers are produced
in the spring on small stems that rise from the center of clumps of glossy,
leathery leaves that are 6-12” long. The leaves often turn an attractive
bronze in the winter. Most species of Bergenia reach 12-18” tall. It
prefers humus-rich, moist soil and dislikes extreme heat and drought, but
can tolerate some exposure and poor soil, which actually enhances the winter
leaf color. Protect from snails and slugs.
Evergreen
Candytuft (Iberis sempervirens). Light shade to full sun, zones 5-9.
Evergreen candytuft forms a foot high mound of glossy, narrow, dark green
leaves and bears white, flat clusters of flowers from March through June. It
may bloom again in the fall and winter in mild climates. Deadhead to
encourage continued blooming. Candytuft tolerates any well-drained garden
soil and prefers regular watering.
Feverfew
(Tanacetum parthenium). Light shade to full sun, zones 4-9.
Feverfew is a low, spreading plant that is covered by an abundance of small,
white, daisy-like flowers from July through August. Both single and
double-flowered types are available; the single flowering type self-sows
prolifically. The plant tolerates a variety of soils, but prefers sandy,
loam soil. Although it will perform well in light shade, it blossoms most
profusely in full sun.
Geranium,
Cranesbill (Geranium). Light shade to full sun, zones 4-9.
This genus includes over 300 species, usually bearing white, pink, purple,
or blue saucer or star-shaped flowers. Most geraniums prefer moderately
fertile, well-drained soil, but will tolerate moist soil. Remove faded
blossoms and leaves to encourage further production. Many geraniums cease
flowering during very hot temperatures.
Goatsbeard
(Aruncus dioicus). Light shade to full sun, zones 3-7.
Goatsbeard has tall, white plumes rising from dark green, shrub-like
foliage. The plant grows
5 to 7 feet tall but does not require staking, and prefers moist, humus-rich
soil.
Globeflower
(Trollius).
Light shade to full sun, zones 5-8.
These
three foot tall bushy plants produce rounded, yellow and orange flowers in
late spring and early summer. They thrive in moist, heavy, humus-rich soil,
although you should avoid planting them in boggy soil. Deadhead to prolong
blooming. Globeflowers prefer shade and can tolerate direct sun only in
cooler climates and if kept moist.
Golden
Groundsel (Ligularia dentata). Light
shade to full sun, zones 4-8.
Golden groundsel bears numerous clusters of orange-yellow flowers on tall
stalks from midsummer to autumn and can attain heights of 3-5 feet. The
large, kidney-shaped leaves reach 12” wide. Give the plant moist, rich
soil in light shade. High temperatures will cause the leaves to wilt. Golden
groundsel cannot tolerate drought or soggy soil. Protect from snails and
slugs.
Hellebore
(Helleborus). Light shade to full sun, zones 5-9.
Hellebores bear long-lasting, pendent or cup-shaped flowers of various
colors and have leathery, toothed leaves. Hellebores are especially
effective when naturalized in a woodland garden; smaller species are ideal
for rock gardens. Hellebores tolerate a range of moist, fertile, humus-rich
soil. Most species prefer neutral to alkaline soil. All parts of the plant
cause stomach upset if ingested. Protect hellebores from slugs, snails, and
aphids.
Japanese
Iris (Iris ensata , syn. I. kaempferi). Light shade to full sun, zones
5-8.
In June and July, the Japanese iris bears gorgeous flowers in white, blue,
purple, or pink, on stems four feet high. The sword shaped foliage grows
three to four feet and looks good all season. The plant requires acidic,
humus-rich, moist to boggy soil. The Japanese iris will self-sow
prolifically if it finds growing conditions favorable. Note: Irises
can be divided into two groups: 1)Rhizomatous, which includes Bearded,
Beardless, and Crested Irises, and 2) Bulbous, which includes Reticulata,
Juno, and Xiphium Irises. While bulbous irises prefer full sun, almost any
rhizomatous iris will perform well in light shade.
Knotweed
(Persicaria).
Light shade to full sun, zones 3-8.
Both
annual and perennial varieties are available. Knotweed can be invasive, as
the name implies, but it is an undemanding plant in the shade border. The
plant bears spikes of long-lasting, cup-shaped, white, pink, or red flowers,
which are followed by brownish red berries. Most varieties prefer moist
soil, but P. bistorta will tolerate dry soil. This plant may cause skin
irritation in some people, and ingestion will cause stomach upset.
Lady’s
Mantle (Alchemilla mollis). Light shade, zones 2-9.
The attractive foliage has kidney-shaped, pale green leaves that may be
pleated and have a fine covering of silky hair. The airy clusters of
yellow-green flowers are long lasting. Prefers moist, humus-rich soil;
deadhead to prevent prolific self-sowing; cut back and water for repeat
flowering in autumn.
Leopard’s
Bane (Doronicum cordatum). Light
shade, zones 4-8.
Leopard’s Bane has bright yellow, daisy-like flowers that bloom abundantly
above large, heart-shaped leaves. The plant will become dormant in the
summer, so intersperse individual Leopard’s Bane plants with other plants
that will grow quickly enough to fill in the empty space. The plant can
reach three feet tall and spread quickly. The centers of the clumps die out
and require division in the fall. Grow in moist, humus-rich, preferably
sandy soil. Leopard’s bane will not tolerate drought.
Lilyturf
(Liriope).
Light shade to full sun, zones 7-10.
Liriope
forms clumps of wide, dark-green, grasslike leaves up to 2 feet tall. Violet
spikes of flowers appear from midsummer to fall, and are followed by dark
blue berries. Liriope tolerates a wide variety of soils and needs only light
watering during the summer.
Marsh
Marigold (Caltha
palustris). Light shade to full sun, zones 3-7.
Marsh
marigold bears bright yellow flowers above rounded leaves, growing 12-18”
high. It performs well in wet, soggy soil or standing water and blooms in
the spring. The entire plant goes dormant by midsummer. The plant can
tolerate drier soil with frequent watering and a generous layer of mulch. If
grown from seed, the plant will not bloom until its third year.
Meadowrue
(Thalictrum rochebrunianum). Light shade, zones 5-9.
During the summer, meadowrue produces airy clusters of lavender flowers on 3
foot stalks that rise from 18”-24” tall clumps of finely textured
foliage. The plant prefers deep, evenly moist, humus-rich soil.
Mondo
Grass (Ophiopogon japonicus). Light
shade to full sun, zones 7-10.
Mondo
grass forms clumps of narrow, curved, dark green leaves that are 8-12”long.
In the summer it bears short racemes of white or lilac flowers, which are
followed by blue-black berries. The plant prefers moist, slightly acidic,
humus-rich soil. Protect new plants from snails and slugs.
Plantain
Lily
(Hosta). Light shade to dense shade, zones 3-8.
Hostas
are grown primarily for their beautiful foliage – large, bold leaves that
come in all shades of green and many different variegations. The flowers
produced from July to October are spikes of lily-like flowers in lilac,
mauve, or white. Hostas prefer rich, evenly moist soil, and can last up to
30 years in one spot. Protect from snails and slugs.
Primrose
(Primula).
Light shade, zones 4-8.
The
Primula genus consists of 425 species that tolerate a variety of growing
conditions. The dark greens leaves form basal rosettes, and have attractive
bell-shaped flowers that may cluster together among the leaves, or grow on
thick stalks in umbels or spikes. The blooming season lasts from late winter
to midsummer in temperate regions. Flowers are available in a wide variety
of colors. Primulas prefer evenly moist, rich soil.
Purple
Coneflower (Echinacea purpurea). Light shade to full sun,
zones 4-9.
Echinacea grows 3 to 5 feet high and blooms from July through September. Its
flowers have purple, drooping petals that surround a dark brown, conical
center. Native to prairies and meadows, the plant prefers sandy,
well-drained soil. Provide light feeding and moderate amounts of water;
light shade produces richer colors than full sun, which tends to fade the
flowers. Protect from Japanese beetles, which can decimate the plant.
Siberian
Bugloss (Brunnera macrophylla).
Light shade to full sun, zones 3-7.
Siberian bugloss has abundant numbers of small blue flowers that cluster
above large, attractive, heart-shaped leaves in the spring, reaching 12-15”
tall. It will tolerate a wide range of soil conditions, but prefers moist,
humus-rich soil.
Solomon’s
Seal (Polygonatum).
Light shade to dense shade, zones 3-9.
Solomon’s
seal has attractive, long, arching stems (some types have variegated leaves)
and bears pendent, bell-shaped, white, pink, or light green flowers along
the lower sides of the stems. Grow in fertile, humus-rich soil. Although
Solomon’s Seal prefers moist soil, it will perform well in dry soil, and
tolerates root competition, making it a good choice to plant under trees
that have shallow root systems. All parts may cause stomach upset if
ingested. Protect from slugs.
Trinity
Flower (Trillium). Light shade, zones 5-8.
The trinity flower has three dark green, glossy leaves to each stem, which
bear white or pink flowers, each having three petals. Berries follow the
flowers, and the plant height varies from 1 to 3 feet. Plant during the
autumn in deep, rich, evenly moist soil. Protect from snails and slugs.
Violet,
Pansy (Viola).
Light shade to full sun, zones 4-9.
These five-petaled flowers bloom profusely all summer and may self-seed
freely. They prefer fertile, humus-rich, moist soil. Deadhead to prolong
flowering. Some vigorous plants may require you to cut back growth after
flowering to maintain neat shapes.
Virginia
Bluebells (Mertensia pulmonarioides,
syn. M.virginica). Light shade to dense shade, zones 3-7.
During the spring, Virginia bluebells have light blue, pendent flowers that
hang in clusters from branching stems reaching to 18” high. Give the plant
evenly moist, cool, humus-rich soil. Allow foliage to die back naturally;
bluebells will self-sow in favorable growing conditions.
Wild
Sweet William, Blue Phlox (Phlox
divaricata ). Light shade to full sun, zones 4-8.
This semi-evergreen perennial bears light blue and white flowers in spring.
The plant reaches a height of 12” and spreads to 20”. It prefers
fertile, humus-rich, moist soil.
Windflower
(Anemone). Light shade to full sun, zones 3-8.
Open clusters of white or pink flowers are borne above large, deeply lobed
leaves that resemble maple leaves. Although easy to care for, they resent
any disturbance once established. Windflower grows from 2-5 feet tall and
needs moist, humus-rich soil. Plants will tolerate full sun only in cool
climates.
[ Groundcovers for Dry Shade ]
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