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They Want New Yard to Be Energy-Efficient

August 05, 1990

QUESTION: We just built a new home and are now in the process of landscaping. I've heard there are designs to help conserve water and energy. Please tell me more.

ANSWER: Your timing is perfect because you're just beginning. Landscaping can be designed to use water efficiently and to provide protection from wind and strong summer sun. Water- and energy-efficient landscaping involves selection of plants/trees, preparation and maintenance of soil and planting in zones.

Energy-efficient landscaping helps control the amount of solar energy (direct sunshine) a home receives in summer and winter. The sun's rays enter your home through east- and south-facing windows in winter.

Planting trees that drop their leaves in the fall assures available sunlight can reach your home in the winter. This extra sunlight may supplement your regular heating system.

To further maximize the solar-heat gain, consider thermal window shades to reduce heat loss at night or during overcast days.

In the summer, heat buildup occurs through west-facing windows. Shading can be provided by planting dense trees, shrubs, hedges or vines on the west side of the home. Ground surfaces surrounding the home that indirectly heat the home by reflection and radiation (such as patios, driveways) can be shaded too.

As for wind--evergreens are generally more effective than deciduous trees at blocking the wind. Maximum protection is provided at a distance five times the height of the trees. Savings on both heating and cooling bills will be higher for homes that are leaky to begin with. For the greatest savings, make sure to properly caulk and weatherstrip.

Landscaping can improve water-efficiency as well by reducing the water, fertilizers and maintenance required for a healthy yard. During the summer, you can use as many as 1,000 gallons of water a day, which is twice what you may use in winter. Here are seven basic water-saving steps to follow.

--Plan for three planting zones. A primary zone for high water use includes your lawn. Perennials, annuals and water-conserving shrubs and trees primarily make up the secondary zone. And lastly, a minimal zone--water conserving plants that require little or no supplemental irrigation--should be planted.

All plants (regardless of the zone) need extra water initially to become established. The root ball cannot be allowed to dry out without dire consequence. Planting at cool, wet times of the year (rather than during hot summer) will help.

--Select low-water-demand (native) plants. Your local nursery can provide recommendations. Avoid overcrowding by limiting plants in each area. The greater the soil per plant, the greater the available water in time of drought.

--Limit turf areas. Keeping a lawn green requires a lot of water. In fact, lawn and garden watering cause us to use nearly twice the amount of water we would otherwise use. To reduce water use, it's best to devote no more than 40% of your land area to lawn.

--Improve soil to reduce water needs. By removing thatch (dead grass), eliminating weeds and aerating compacted soil (poking holes about six inches apart across the entire surface), you can improve the soil's capacity to hold moisture. Less water will then be required.

--Use efficient irrigation systems. Sprinkler systems with timers and appropriate drip irrigation can save water. A trickle or drip-irrigation system allows for a slow, steady supply of water to the plant roots. Drip irrigation is not appropriate for every watering need. For example, lawns generally require sprinkler systems.

--Use mulches in planting beds. Old grass clippings, leaves, chipped wood and finished compost make good mulch. Two inches of mulch can reduce water demand significantly. Mulches also reduce soil erosion from the wind, discourage weeds from growing, keep soil cool and improve soil condition (when organic mulch is used).

--Proper maintenance eliminates stress on plants and reduces the need for chemical treatment such as fertilizers and pesticides.

For example, thatch and soil compaction are eliminated by airification and top dressing (1 part peat 6 parts sand, 3 parts sandy loam makes a good top dressing).

Another good example: If a tree shade is responsible for a turf fungus, removing its bottom branches to allow more light can reduce fungus. Also, planting a shade-tolerant grass (such as a red fescue) might do the trick.

Produced by the Washington Energy Extension Service, a division of the Washington State Energy Office. SEVEN STEPS FOR WATER-EFFICIENT LANDSCAPING Plan for three planting zones.

Select low-water-demand (native) plants.

Limit turf areas.

Improve soil to reduce water needs.

Use efficient irrigation systems.

Use mulches.

Maintain plants properly.

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