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University
of Rhode Island GreenShare Factsheets
Shade
Gardens
Many gardeners view shade as a challenging situation for
growing plants. While some plants do not grow well in low light,
numerous others thrive under these conditions. Just as moisture,
temperature, and soil conditions may limit plant growth, the
amount of shade present may determine which plants will grow
successfully. The key is to discover which ones are adapted
to the conditions in your yard or garden.
Landscapes change their degree of shade over time. As
trees and shrubs mature, the landscape receives greater shade.
What was once a sunny garden may evolve into a shady one. Analyze
the degree of shade in your garden periodically to determine
if changes in plant materials may be needed due to increased
shade from a maturing landscape. In addition to low light levels,
plants growing in the shade must compete with shading trees
for nutrients and water, as well as tolerate poor air circulation.
The best way to cope with low light
levels is to choose plants that do well in less light. See
our GreenShare Factsheet
on Perennials for Specific Sites for
some recommendations of plants which tend to thrive in shady
environments. Plants that tolerate low light levels often will
grow more vigorously in brighter areas, provided they receive
adequate moisture.
Light shade may be described as an area that is shaded
but bright. It may be completely shaded for only several hours
each day. The sun's rays may be blocked by a wall or building
for several hours at midday, but the area is sunny the rest
of the day. Light shade may also be found in areas that receive
filtered or dappled sunlight for longer periods. Edges of shady
gardens or areas under the canopy of solitary, lightly branched
trees are typical of filtered sunlight. During the heat of
summer, light shade at midday will provide a beneficial cooling
effect. Flower and foliage color may be more brilliant when
plants are shielded from intense midday sunlight.
Partial or medium shade is present when direct sun rays
are blocked from an area for most of the day. Many established
landscapes have large areas of partial shade, where sections
of the yard are shaded by mature trees for much of the day
but receive some direct sun early or late in the day. Bright,
north-facing exposures may also be classified as medium shade.
Full shade lasts all day. Little or no direct sunlight
reaches the ground at any time of the day. There may be reflected
light from sunnier areas of the yard or off light-colored walls.
Dense shade refers to full shade under thick tree canopies
or in dense groves of trees. Areas under stairways, decks or
covered patios on the north side of the house receive full
shade.
Keep in mind that light patterns change with the seasons.
An area that is in full sun in summer when the sun is high
in the sky may have medium shade in spring and fall, when the
sun is at a lower angle. Study your garden through the seasons
to accurately determine what type of shade is present.
Available sunlight may be increased by selective pruning.
Removal of lower limbs on large trees may increase light levels
significantly. Large shade trees are valuable resources which
in most cases should be preserved. However, removal of diseased,
unattractive or poorly placed trees improves the beauty of
your property and increases the light available for plant growth.
Take advantage of reflected light, if possible. White
or light-colored surfaces reflect more light than dark-colored
ones. Light-colored house siding or fences may increase available
light to plants.
Plants growing in the shade often must also compete with
roots of shading trees for nutrients and moisture. Shallow-rooted
trees such as maples and willows are particularly troublesome.
Adding organic matter to shade
garden soils will help. Most woodland species are accustomed
to growing in soils rich in
leaf litter compost. Raking and removal of leaves each fall
in the typical landscape disrupts this natural nutrient recycling
process. If leaves are not removed, they can mat down and smother
shade garden plants, but shredded leaves can be safely applied
as a mulch. Another option is to compost the leaves first,
and apply the compost in core aeration holes or in small pockets
dug into the garden. Do not haul in several inches of compost-rich
amendment to till into soil under shade trees. Some species,
such as oaks, are extremely sensitive to changes in soil depth
within their root zone. In addition, tillage will damage many
of the tree's roots, starting a decline from which the tree
may never recover. If the gardener is patient, earthworms will
eventually incorporate surface-applied organic matter. Organic
matter loosens heavy clay soils, improving drainage. In sandy
soils, organic matter will increase the water-holding capacity.
As organic matter breaks down, it also releases nutrients to
the plants.
Roots competing for limited surface water may cause shade
gardens to dry out more quickly than sunny sites during extended
dry periods. Some shade-tolerant plants are adapted to low
moisture situations, while others require moist shade. Provide
water according to the needs of the plant.
Branches or walls that cast shade also block air movement.
Poor air circulation coupled with lower light levels means
foliage of plants stays wet longer in the shade than in sunny
areas. Most plant disease problems are worse under these conditions.
Prevent disease problems by selecting disease-resistant varieties
when available. Space plants farther apart in the shade to
allow more air movement around each individual plant. Water
with soaker hoses or drip irrigation systems to avoid wetting
the foliage. Removal of lower tree limbs may funnel breezes
underneath the tree canopy, thereby improving air circulation.
Bright, bold colors are less common in shade tolerant
plants than in sun-loving ones. Flowers are usually produced
less abundantly in the shade as well. For these reasons, shade
gardens are often more subtle and restful than sunny ones.
Plant textures, forms and slight color differences become more
important elements of the design.
Texture has many aspects. Large-leaved plants such as
hostas have a coarse texture, while finely divided fern fronds
create a fine texture. Strong contrasts in texture accentuate
their differences. Use strong textural contrasts only where
emphasis is needed.
Pyramidal or upright, columnar plant forms serve best
as accents in the shade. Rounded, weeping or spreading forms
create a more spacious effect and can be used more liberally
in the design.
Glossy leaves have more impact than dull or velvety ones.
Variegated or yellow-green foliage is evident in the shade
more than solid green or blue-green foliage. Light colors --
white, cream, yellow and pastel pink--stand out in the shade.
Deep reds, blues and purples may fade into the shade unless
set off by a contrasting lighter color. To emphasize plantings
in the shade, concentrate on plants with light-colored flowers
or foliage.
Adapted from Dennis S.
Schrock, Department of Horticulture, University of Missouri-Columbia,
2001
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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