The garden has been considered an essential element of a happy and full life since the beginning of time.
As a result, landscape design has enjoyed equal stature
with the major arts. Th e garden or landscape designer has
held prominent positions in many cultures, including the
courts of ancient Egypt, Renaissance Italy, Imperial France,
China, and Japan. Master designers have generated many of
the techniques of design through their own artistic talent,
experience, and interpretation, as well as through strong
sensitivity to the client, qualities of the site, and plants and
materials used.
Today, landscape design is popular with the average
homeowner. However, moving high-garden type art to
the backyard context is diffi cult. When using plants in
landscape design, the result is usually oversimplifi ed and
misinterpreted. Easy-to-follow “cookbook” landscape rules
can be found in many popular landscape design magazines.
Unfortunately, these publications do not discuss the overall
three-dimensional structure of the design. Instead, they
discuss the use of plants in terms of individual ornamental
characteristics including form, color, and texture. In this
type of approach to planting design, the most immediate
visual attractions within the landscape are emphasized. One
of the more important, basic, and classic aspects—the cre-
ation of three-dimensional outdoor space with plant walls,
fl oors, and ceilings—is overlooked. Th at is unfortunate
since this aspect of planting design can evoke the longest-
lasting overall impression within the outdoor experience.
Th is publication outlines the oft en-overlooked concept
of landscape design with plants as architectural, engineer-
ing, and aesthetic tools that build an enjoyable outdoor
environment. It is not intended to present any textbook
rules for home landscaping nor discuss the most appropri-
ate use of specifi c plant species. Such techniques of design
are developed through one’s own design experience or
through viewing the design of others.
HO-62
Landscape
Design with Plants:
Creating Outdoor Rooms
Janice A. Cervelli, former Professor, Landscape Architecture
Plants as Architecture
Plants with respect to architecture can perform two
roles. Th ey can complement and reinforce the existing
architecture of the house or structure, and they can create
outdoor rooms.
Trees, shrubs, and ground covers can be used to em-
phasize the desirable architectural lines and masses of the
house. Th e form and branching pattern of particular trees
and shrubs can echo the vertical, horizontal, and diagonal
roof and wall lines of a house. A pleasing, unifi ed, and
harmonious appearance can result (Figure 1).
Figure 1. Plants soften and fi lter light as well as blend with natural
material.
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Plants can be used to soft en and balance harsh and
awkward architectural angles, masses, and materials (Fig-
ure 2). Before actually purchasing and installing plants,
an owner can plan the locations by assessing the desirable
and undesirable qualities of the house. To do this, take a
photograph of the front and back of your house, and sketch
where plants are needed. Judge ultimate plant sizes at this
time to ensure harmony with the house.
You can use plants to frame desirable views of your
house. Remember, the best views are not always from
straight on. Oft en, views to the entrance or windows are
more interesting from an angle as one approaches from a
drive or walkway (Figure 3). Selective framing allows the
viewer to see only the best parts of the house and yard in
a sequence that builds up curiosity.
Figure 2. Plant and house forms are in harmony.
Figure 3. A grove of river birch is used to screen this house
from the road. A sweeping drive, brought in from the left,
focuses on the entrance of the house and discloses the rest
of the house in a sequence.
Views of the house are important, but views from inside
the house onto the front or backyard are even more so, and
they merit consideration. A large shrub or medium-sized
deciduous tree with lacy foliage and branching pattern can
be used to provide enframement, a sense of scale, and an
interesting foreground to the viewer from inside. In the
winter, the branching pattern creates the same eff ect. Such
a treatment can double your enjoyment of the landscape.
Be careful to size and space the plant so that it does not
overgrow and block windows.
Th e human eye has a tendency to follow the outline
of the objects in the landscape. With this idea in mind,
you can aff ect the apparent size of your house. By placing
plants in increasing height away from the house corners,
the horizontal lines are emphasized and its apparent length
increases (Figure 4). Th is is especially helpful with boxy,
two-story structures.
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Th e same arrangement in a scaled-down version can
emphasize and lead the eye to the entrance or large picture
window. Placing large, conical evergreen plantings on either
side of the entrance oft en has the disastrous opposite eff ect
of emphasizing the vertical lines, making the house appear
taller and narrower and creating an uninviting, inhibiting
appearance (Figure 5).
Th e proper placement of foundation plantings raises
similar concerns. Evergreen foundation plants originally
became popular for masking exposed foundation walls that
were two to three feet thick and made of concrete block.
Most foundations on newer homes rarely expose more
than 12 inches and can be masked with a ground cover.
Older homes oft en have attractive stone foundations that
should be emphasized, not masked. It is not always neces-
sary to place great amounts of expensive evergreen plant-
ings around the entire house.
It also is unnecessary to restrict the type of plant to
evergreens such as yews or boxwood. Deciduous trees and
shrubs are equally eff ective in complementing architecture.
Deciduous plants can unify the architecture through a
Figure 4. By graduating plant sizes away from the house, the apparent size
of boxy, two-story structures is increased.
Figure 5. Tall evergreens create an uninviting,
inhibiting appearance to this entrance.
branching pattern. For example, horizontal house lines can
be unifi ed with a horizontal branching pattern. Deciduous
plants also add an infi nite variety of color and textural
interest throughout the year. All of this is possible without
distracting from the main feature, the house.
Th e growth habits and requirements of plants must be
considered when they are used close to the house. When
sizing a plant, take into consideration its mature height
and width. Otherwise, an overgrown and crowded appear-
ance that dwarfs and hides the house can result (Figure
6). Consult a number of information sources concerning
plant growth. Check any special cultural and maintenance
requirements of the plants such as soil type, moisture, sun
exposure, and pesticides.
Figure 6. Plants that reach large
sizes at maturity are often planted
too closely to the house when
small. When mature, they dominate
and make the house look smaller.
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Creating Outdoor Rooms
Th e word architecture suggests the creation of spaces or
rooms for use by people. Inside the home, fl oors, walls, and
ceilings are used to create diff erent settings for a variety of
activities ranging from gardening, handiwork, and cooking
to formal entertaining, relaxation, and active sports. As a
result, greenhouses, garages, utility rooms, kitchens, living
rooms, dens, studios, and gyms are created.
Th e development of outdoor architecture or outdoor
rooms utilizes the same elements as indoor architec-
ture—fl oors, walls, and ceilings. Th e diff erence is that the
elements of outdoor rooms are composed of plant materi-
als that have a changing and dynamic, living quality. As
time passes, the room will grow and mature and provide
a varying seasonal display each year.
Th e second role of plants with respect to architecture
is the creation of outdoor rooms. Before creating such
rooms, determine what number, type, and size of spaces
are needed. List what type of outdoor activities you expect
to conduct. Th e list might include entertaining, cooking,
gardening, reading, painting, sunning, or relaxing. You
might also want space for children’s play, active sports, stor-
age, building projects, hobbies, and maintenance. Th ose
activities that require a separate room must be noted, as
well as those compatible activities that can be combined
in one space, such as a workspace, storage, and parking
area. Note the desired qualities of the space; that is, sun
or shade, or hard or soft surfacing.
Th e creation of the various outdoor spaces can take
one of two approaches. Th e most typical involves the new
homeowner in landscaping a house that had previously
received some landscaping and where outdoor spaces such
as patios already exist. Th e approach is similar to that of
redecorating an older home: the basic fl oor plan remains
the same while the qualities of the fl oors, walls, and ceil-
ings are changed with the addition of a new rug, wallpaper,
paint, and furniture.
In landscaping, the designer should assess the condition
of existing plants and views and determine what is to stay
and what needs improvement. Th e result may be a simple
cleaning-out, trimming, replanting of existing plantings,
or planting of new foundation plantings. Th is approach
may appear to be the most effi cient. However, it fails to
completely consider the new owner’s special needs.
Th e construction of most new homes is also completed
with little consideration of outdoor rooms. Th e front and
rear yards are left as two large spaces with the side yards
as small voids (Figure 7). Foundation plantings around the
house, hedges along the property lines, and a few shade
trees are oft en added by the fi rst owners, but these addi-
tions will do little to encourage the most effi cient spatial
development in each yard.
Figure 7. A small side yard developed into an
intimate strolling garden.
Th e second approach to room creation is the develop-
ment of new outdoor rooms. Compare this to changing the
actual fl oor plan of an old house by knocking out walls or
building an entirely new structure. To develop a new room,
assess the qualities of the existing site. Such qualities as
views, topography, drainage, sun and wind exposure, and
proximity to the house can suggest appropriate locations
for activities. Th is type of assessment requires you as the
designer to experience the site and characteristics on a
frequent basis through all of the seasons. Th is activity will
allow you to get a “feel” for the site and better match its
qualities to your needs.
Th e simplest approach to locating new rooms is to begin
by extending the house’s interior rooms to the exterior. Th e
outdoor room will take on a function and quality similar
to the indoor room, producing a stronger relationship and
harmony between the house and the landscape as well as
increasing the apparent size of both. In this regard, the
location of the house on the property and the fl oor plan of
the house can help with strategic window and door loca-
tions overlooking good views. Th e small patios and decks
added to new homes by developers are a positive step in
this direction. Similarly, the entrance foyer or vestibule
can be extended outward by expanding and developing
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the front porch and area. Garage and driveway access
can be extended to include an outdoor work and storage
space. Defi ne these rooms with plant or constructed walls,
fl oors, and ceilings to avoid blending them into one large,
characterless space.
Further development of each individual outdoor room
should begin by determining whether the space is inwardly
or outwardly oriented (Figure 8). Inwardly oriented space
is characterized by either complete or nearly complete
enclosure and a strong central focal point. Certain areas
for sitting, sculpture displays, patios, and hot tubs require
enclosure for purposes of privacy, quiet, and concentra-
tion. Rooms within rear yards will typically contain such
activities and require this type of orientation.
Outwardly oriented rooms are enhanced by amenities
outside the space such as good views and breezes. Certain
spaces may require selective cutting of existing plants to
provide good views or the installment of new plants to
Figure 8 (top). Inwardly focused space.
Figure 8 (bottom). Outwardly focused space.
frame the views. In most situations, activities taking place
within the front yard are more public in nature and will
require free visual access on and off the site and little en-
closure; thus, it is outwardly oriented.
Once you have determined the orientation and function
of the outdoor room, you can defi ne the basic elements
of architecture: fl oors, walls, and ceilings. Th e fl oor of an
outdoor room can provide for continuity and a comfortable
transition throughout a number of spaces. Th e fl oor can be
created with pavement, lawn, ground cover, annuals and
perennials, or low (1’ to 3’) shrubs.
As in any building, the activity to take place in a room
will determine the size and material of the fl oor. Just as work
and exercise areas or kitchen areas have a durable linoleum,
tile, or wood fl oor, similar outdoor areas in the yard should
be underlain by a durable lawn or even hard pavement.
Likewise, as a formal living room or entertainment area
calls for a more decorative, plush carpet, so should a formal
outdoor garden, patio, or terrace. A variety of swathes and
ribbons of ground covers, annuals, and perennials provide
the highly decorative eff ects of an oriental rug if carefully
planned to take full advantage of seasonal interest.
Th e type of plant materials used to defi ne the outdoor
room also will suggest the function. Lawn areas typically
invite low volume, pedestrian traffi c, and relaxation, while
spots with ground covers, annuals and perennials, and low
shrubs do not. You can create an activity-oriented room
using a lawn area bordered by ground cover or low plant-
ing beds. Or a passive viewing garden can be created with
more elaborate planting combinations and little or no lawn
(Figure 9).
Figure 9. An outside extension of the entrance foyer creates a
viewing courtyard of elaborate plant combinations instead of lawn.
6
In the same manner, suggest traffi c volume and direction
with the creation of pathways using lawn and planting beds.
Th ese pathways can act as a kind of breezeway to link two
diff erent outdoor rooms (Figure 10).
Th e extension of low planting beds to taller shrubs
and tree masses and hedges can create very eff ective walls
with which to enclose an outdoor room and direct traffi c
to it. Choosing the type of plant to use as a wall is similar
to choosing a wallpaper for its texture, color, and ease of
maintenance. Th e leaf, fl ower, and winter branching pat-
terns of individual plants provide the same visual qualities
as wallpaper. Height and thickness or density of the wall are
determined by inward or outward orientation of the space
and required degree of enclosure. Low to small shrubs (2’
to 5’) can be used to suggest partial enclosure but still al-
low views out of the space. Taller, dense evergreen shrubs
(5’ or taller) in combination with smaller shrubs and trees
provide the strongest enclosure. Tall and medium trees (25’
or taller) provide overhead enclosure but also allow views
from underneath the canopy (Figure 11). Plants with more
open growth habits can provide a partial screen to fi lter
views.
Outdoor walks also can be used eff ectively to screen
negative views, sounds, and smells near the space (Figure
12). Th e size and intensity of these negative elements will
determine the size, spacing, and density of the screen. Poor
views will generally require dense evergreen plantings
or constructed screens for year-round eff ectiveness. Un-
pleasant smells require a combination of aromatic ground
covers, annuals, perennials, shrubs, and trees to be placed
downwind between the source and the property owner. An-
noying sounds are especially diffi cult to screen with plants
on small sites and require a combination of constructed
walls, fences, and landforms.
Plant combinations can act as fl oors. Walls can frame the
views in both inwardly and outwardly oriented space. Use
low shrubs and ground covers as a foundation to off set a
central focal point such as a sculpture piece or patio in an
inwardly oriented space (Figure 13). Taller shrubs and trees
enclose a space and lead the eye to a central focal point.
Framing an outward view involves the same concept but
uses trees, ground covers, or planting beds to draw the eye
out of the space (Figure 14).
Outdoor ceilings are the most important part of the
room, and you can create them with tall shrubs (10’ or
taller) and small, medium, and large trees (15’ or taller).
Th e orientation and scale or size of the room will determine
the type of ceiling. Inwardly oriented space should have
a wide variety of ceiling heights, density, and texture. Let
desired intimacy or the scale determine the ceiling height.
Figure 10. Planting beds and walks act as a breezeway between
driveway and entrance courtyard.
Figure 11. Various plant types, heights, and combinations create
walls, partial screens, and overhead canopies.
Figure 12. A sculptured hedge creates a partial screen between
parking area and entrance courtyard.
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Rooms intending a grandiose eff ect such as a dining room
or ballroom require high ceilings. Victorian homes with
10- to 12-foot high ceilings bring a distinctively diff erent
perceptual eff ect than the 8-foot high ceilings in more
contemporary homes. With this in mind, you can create
your style of outdoor room.
Th e density of the tree canopy and the overlap will de-
termine the amount of light in the room. Th e darker the
room, the heavier and smaller it may appear. It may also
render a cooler, more mysterious eff ect on the viewer. A
brighter room is generally perceived as lighter, airier, more
comfortable, and larger to the viewer. Fine-textured plants
such as honeylocust render a lighter, airier enclosure. Tall,
dense evergreen shrubs and trees such as yews, pines, and
fi rs render a darker wall and canopy enclosure. Careful
Figure 13. Low planting beds and overhead canopy enclose and
complete this outdoor sitting area.
Figure 14. An overhead tree canopy helps to frame the outward
view from this wood deck.
planning of the interplay between sun and shade at diff er-
ent times of the day can also bring about dramatic eff ects
of light and dark.
Th e texture of the leaf and branching patterns across the
sky in both summer and winter months also adds to the
decoration of the room. Th e basic function, location, and
orientation of the outdoor room can be further refi ned by
determining the main motif or theme of the space.
The Composition of the Outdoor Room
We have looked at how plants can be used to enhance
and frame a house or property and how to create outdoor
space or rooms with plants as architectural elements. Th e
next step is to give a pleasing form to the composition
through the use of classic design principles such as unity,
balance, and rhythm. Th ese basic design principles are
common to all art works. Th ese qualities make artistic cre-
ations continually beautiful, interesting, and meaningful.
Plants as well as man-made structures can be combined
in an infi nite variety to bring about balance, unity, and
rhythm.
What is meant by balance, unity, and rhythm? In a bal-
anced composition, the elements of design are distributed
in some organized arrangement or order. Symmetrical
and a