University of Vermont Extension
Department of Plant and Soil Science
Anytime News
Article
PERENNIALS FOR SHADE
Dr. Leonard Perry, Extension Professor
University of Vermont
Whether you have a mainly wooded
landscape, or live in a neighborhood where the trees have matured into
a dense canopy, there are some hardy herbaceous perennials
you can grow under them successfully.
Allegheny spurge, Cinnamon fern, barrenwort, foamflower, astilbe,
hostas, bigroot geranium, and Japanese forest grass all are adapted to
a shady
habitat. These all need a well-drained
soil, and are hardy to at least USDA zone 4 (average annual minimum
temperature
of –20 to –30 degrees F).
Allegheny spurge (Pachysandra
procumbens), although native to the southeastern U.S. is hardy in the north. It is
semi-evergreen, and related to the more aggressive, common, and non-native
Japanese spurge. Its green leaves are
only about three inches high with the white flower spikes in May just above the
leaves. Plant it in part to full shade,
and cut back leaves in spring if they are brown.
Cinnamon fern (Osmunda cinnamomea)
is so named from the upright cinnamon-colored spikes that bear the spores (like
seeds for ferns). The fuzz from these
may be used by hummingbirds to line their nests. The long fern leaves are upright in a clump
two to five feet tall. This native fern
prefers moist shade, either full to part shade.
It is effective in masses, or as a backdrop for other perennials.
Barrenwort (Epimedium) is a great
group of low maintenance perennials, native mainly to China.
The plants only get about a foot high, having small flowers somewhat
resembling a columbine. Flowers come in
many colors, depending on cultivar (cultivated variety), from reds and pinks to
whites and yellows. Leaves can have an
attractive reddish cast or margins when they emerge in the spring, and
sometimes in the fall. Water well to
establish, but once established plants will tolerate drought. Morning sun and afternoon shade is best.
Foamflower (Tiarella) is a native
low perennial, leaves under a foot high and flower spikes (generally white or
pinkish) in early summer getting up to a foot high. Most form clumps, although some selections
spread into effective groundcovers. Many
cultivars have been released in recent years having all manner of leaf shapes
and colorations—their main attraction.
They tolerate dry soil once established, and grow well in part shade but
tolerate full shade.
False spirea (Astilbe) prefers
bright to part shade, and really needs a moist soil. If it dries out, the leaves turn brown and
wont recover. Dry plants may not die,
unless young or prolonged drought, but may not send up new shoots until next
year unless they die back early in the season. Many cultivars exist of this
perennial, with the characteristic two to three foot dense flowerheads in
pinks, reds, or whites. They are
effective massed, or mixed in shade borders with other perennials.
Funkia or plantain lily (Hosta)
are one of the most popular and easiest to grow perennials. There are hundreds of cultivars, from six
inches high and wide to three feet high and five feet or more wide. Leaves come in many color variations, from
solids to mottled to contrasting margins, in creams, whites, various greens and
blues. Some leaves are plain, others
rippled or textured. They withstand full
shade and compete well with tree roots in dry conditions. Most have flower
spikes in late summer above the leaves in whites to purples, often
fragrant. The main pest is slugs under
moist conditions, and deer may browse the leaves.
Perennial geraniums are usually thought
of for full sun, but several such as the wood cranesbill (Geranium
sylvaticum) and bigroot geranium (G. maccrorhizum) do well in part
to dappled shade. They tolerate drought
once established, the bigroot geranium wilting less in shade than it does when
dry in hot sun. Woodland cranesbill has
purple flowers in late spring, while the bigroot geranium has pink or white
flowers in summer. Leaves of the latter turn reddish in the fall.
Most ornamental grasses need full sun,
the Japanese forest or Hakone grass (Hakonechloa) being an
exception. Usually you see one of the
yellow leaved cultivars, ‘Aureola’ with its wide bright yellow leaf margins
being common and a good choice. Only
getting a foot or slightly more high, this perennial can spread into a several
foot wide clump under good conditions with moist soil. Leaves arch, simulating a cascading
waterfall, making it effective on sloping terrain and in masses. It is a good choice to brighten up part to
full shade (less color in full shade), but is generally only hardy to USDA zone
5 (-10 to –20F average minimum).
Look at local perennial nurseries and
garden outlets for these shade perennials, as well as others such as dead
nettle (Lamium), which is not horrid as its name sounds, lungwort (Pulmonaria),
and coralbells (Heuchera).
Lamium tolerates dry soils and bright to full shade. Lungwort prefers moist soils, especially when
young, but can tolerate occasional drought when mature. It grows well in dappled, bright, or part
shade. Coralbells can grow in full sun
if sufficient moisture, but in part shade prefers drier soils. All these three
groups have attractive flowers and leaves.
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