A
surprising amount of water is used in the home landscape. Studies
have shown that as much as 70 percent of water from a municipal water
system can be attributed to residential use. In addition to municipal
water sources, a percentage of water from private sources or wells
also goes to residential use. Of water used at homes, almost half
is used to maintain the landscape.
The problem is that while we live in the Southwestern United States,
we have traditionally landscaped with plants native to England, Japan,
the East Coast of the United States, and other regions with much higher
precipitation. To successfully grow these plants, we must supplement
the natural precipitation with our limited surface and groundwater.
The use of plants with high water demands is not our only landscaping
option; fortunately, neither is removing plants from the landscape.
Our
landscapes may remain beautiful and productive if we use water efficiently
and if we use landscape plants that require less water. A secondary
benefit is that plants with low water requirements are frequently
adapted to the alkaline soils characteristic of New Mexico and other
dry regions. Landscapes using these water-efficient plants are often
called xeriscapes.
The
concept of xeriscape was developed in Denver, Colorado, in response
to water shortages. "Xeros" is a Greek word that means
"dry." Xeriscape refers to a landscape that uses little
supplemental water. It does not refer to a dry, barren landscape,
nor is a xeriscape a "no maintenance" landscape. Like
traditional landscapes, a xeriscape may be designed to minimize
labor or to require frequent care. Many people appreciate beautiful
landscapes, but have limited time to spend tending a garden. By
using plants that are well adapted, mulches that suppress weeds
and conserve water, and drip irrigation to make the most use of
water, these landscapes can have color and fragrance with only monthly
or seasonal gardening chores. Gardeners who like to spend time in
the garden can design a xeriscape to be as labor intensive as a
highly maintained traditional garden, but use much less water. There
is a xeriscape for every gardener.
Xeriscape
is not a landscape style or garden design. Xeriscape is a concept
of water conservation that may be applied to landscapes of any style,
from traditional to English, Japanese, Southwestern, and others.
They may be formal or natural looking. The principles used to develop
xeriscapes are good horticultural practices applied to our unique
desert environment.
Xeriscape
incorporates seven water-conserving principles:
Planning and design.
Efficient
irrigation systems, properly designed and maintained.
Use of mulch.
Soil preparation.
Appropriate
turf.
Water-efficient
plant material.
Appropriate
maintenance.
A good landscape and garden begins with a good design. Water
conservation in the garden can be maximized if it is considered
in the initial planning phase. Xeriscapes can be divided into zones
with different water requirements. An "oasis," a zone
with the highest water use, is usually where people spend more time.
The patio area and perhaps the entry area are candidates for the
oasis. An oasis receives more water and, as a result, is cooler.
This area also may require more maintenance and usually will be
the landscape's most colorful area .
Beyond
the oasis is a transition zone of moderate water use. The transition
zone contains plants that require less frequent irrigation and usually
requires less maintenance. Further away may be a low-water-use zone,
which requires no supplemental water or very infrequent irrigation
during prolonged dry periods. Designing the landscape with areas
of differing water demands is called "hydrozoning."
"Found
water" or "harvested water" that runs off roofs and
paving during storms can be used to reduce the need for supplemental
irrigation. Roof runoff can be directed to the oasis or other areas,
drastically reducing the need for supplemental irrigation in the
moderate- and low-water-use zones. Because water harvesting requires
grading to channel and detain runoff, it should be planned when
the landscape is designed.
Irrigation is necessary in a xeric landscape, at least during the
first few years while the plants' root systems are developing. Following
establishment, irrigation may still be necessary depending on the
landscape design and plants' needs. In New Mexico, many landscapes
need irrigation for at least a portion of the planted area for the
life of the garden. The oasis and the moderate-water-use zones have
the greatest need for irrigation, but it is wise to plan irrigation
even in the low-water-use zone to allow for new planting, changes,
and years of severe drought.
The
irrigation system--whether automatic, manual, or hoses moved as
needed--also is an integral part of landscape planning. It is the
foundation around which the plantings are designed. The water-use
zones--low, moderate, and oasis--should be separate from each other,
and each managed independently. With in-ground irrigation systems,
each zone should be under a separate valve.
The
water should be applied as efficiently as possible. Sprinkler systems
are appropriate in areas of turf, but drip, bubbler, and micro-spray
systems or soaker hoses are more appropriate for shrubs, trees,
and annual and perennial plantings. Efficient irrigation applies
water where it is needed, not where it will be wasted and benefit
only weeds.
Mulch provides a cover over the soil, reducing evaporation,
soil temperature, and erosion. It also limits weed growth and competition
for water and nutrients. Landscape mulch materials vary in their
suitability for various uses.
Impermeable
plastic mulch has a function in the landscape, but is very often
misused. It may be used in areas where the soil must be kept dry,
for example, next to a foundation where termiticides have been applied
and where you are channeling harvested water from one area to another.
Otherwise,
permeable weed barriers, bark, gravel, and other porous mulches
are better because they allow water and oxygen to pass to plant
roots. Dust will eventually collect over the weed barrier fabrics
and allow growth of some weeds, so it is not a perfect solution,
but these porous fabrics are useful for weed control when the bark
or gravel covering it is less than 3 to 4 inches thick, or annual
weed potential is great.
Organic
mulches keep the soil moist and reflect less heat. They work well
with plants adapted to cooler microclimates. Bark mulch should not
be used on steep slopes or in drainage ways because it washes away
in heavy rains.
Some
plants native to very well drained soils grow better in gravel mulches.
Remember, rock mulch becomes very hot in our climate and can injure
or limit growth of some plants. Ultimately, the mulch should be
shaded by landscape plants that will provide environmental cooling.
Using gravel mulch alone as a landscape element may result in increased
home cooling bills and require greater weed control efforts.
SOIL PREPARATION
Soil preparation is an important part of successful xeriscaping
and gardening. When done prior to planting, soil testing can help
determine which plants are best adapted to the site and which amendments
are appropriate for improving the soil for the selected plants.
In the oasis and moderate-water-use zones, adding compost increases
the soil's water-holding capacity. In the low-water-use zone, soil
preparation may only consist of rototilling to loosen the soil and
reduce the soil compaction associated with building construction
in planting areas. Loosening the soil improves root development
and allows better infiltration of water and air needed by plants'
roots. This is important in all water-use zones. However, since
soil disturbance promotes the germination of weed seeds, limit tilling
to areas being planted.
One of the most controversial and misunderstood of the xeriscape
principles is the concept of appropriate turf. Turfgrasses have
a place in the landscape, even the xeriscape. Turf is easy to maintain,
although it requires more frequent care than many other landscape
plants. Turf provides a play surface for children and pets. It is
an important element in cooling the local environment, reducing
erosion, and preventing glare from the sun. Other ground cover plants
can perform these functions--except providing a play area. Consider
where and how large a turf area is desired, how it will be used,
and during which seasons it will be used. You are then prepared
to limit turf to useful spaces and determine which grasses will
best serve your needs. In northern New Mexico and higher elevations
of the state, cool-season grasses are best for areas used extensively
as play areas, especially if this use extends into the early spring
and late fall. Fescue or a fescue-bluegrass mixture is appropriate
for these areas.
If
the use is light or mostly in the warmer months and in southern
New Mexico, use a grass that needs less water such as buffalograss,
blue grama, or bermuda grass. If the area is only for appearance,
other ground cover plants may be more appropriate and may be irrigated
more efficiently. Choose the best plants for each purpose by carefully
defining your needs and purposes before selecting specific plants.
Plants that require less water are becoming more readily available
in the nurseries. There are many very attractive plants for use
in water-wise landscapes. While you may use many of your old favorites
in the oasis zone, there is a wide variety of colorful, fragrant,
and beautiful plants for the less irrigated part of the landscape.
Many have long blooming seasons and attractive leaves. Some provide
autumn interest with colorful foliage and fruit, while others offer
winter interest with their fruit, seed stalks, and winter colors
ranging from silver, to gray, to many different green and brown
shades.
Xeric
plants depend on the formation of extensive root systems to effectively
gather water for proper growth. While they may look unimpressive
in nursery containers, they rapidly become beautiful plants in the
landscape.
Maintaining the landscape cannot be forgotten, even in a xeriscape.
While many gardeners find the time spent gardening very relaxing,
people with less time or other interests may prefer a landscape
that requires minimal time working in the garden. The design will
determine the required maintenance. Any garden will require some
maintenance: pruning, removing trash that has blown into the landscape,
occasional weeding and pest management, checking that the irrigation
system is functioning properly, and adjusting automatic irrigation
systems as the seasons change.
Xeriscaping
offers a way to have beautiful, livable landscapes without excess
water use. It allows areas close to us to be cooler and hospitable,
while investing less water on parts of the landscape in which we
spend less time. Even lower-water-use areas can be very attractive
if the seven xeriscape principles are employed. Using xeriscape
makes our landscapes more compatible with our New Mexico environment.
©2003 Xeriscape Council of New Mexico
webwork by: ABQonline.com
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