Trees for Shade

Trees for Shade

Saving Energy the Natural Way

"A well-placed deciduous shade tree can reduce cooling costs 20 to 40 percent."

Each spring, the thoughts of many California homeowners turn to landscaping. But before taking that trip to the nursery, consider how a carefully-planned landscape can offer much more than beauty. Careful planting will make your home more comfortable and help reduce your cooling and heating bills.

Trees, shrubs and vines all provide valuable shade to moderate summer heat gain in your home. Such plants also create a cool microclimate that can dramatically reduce the temperature by as much as nine degrees Fahrenheit in the surrounding area. During photosynthesis, large amounts of water vapor escape through their leaves, cooling the passing air. The generally dark, coarse leaves absorb solar radiation.

Deciduous trees -- trees that loses their leaves each year -- offer one of the best ways to cut home cooling costs. When selectively placed around a house, they provide excellent protection from summer sun by shading roof, walls and windows. A mature well-placed deciduous shade tree can reduce cooling costs 20 to 40 percent. After the leaves drop in autumn, deciduous trees permit winter sunlight to reach and warm the house.

Experts recommend planting trees on the northeast-southeast and northwest-southwest sides of your house. Unless you live in an area where it is hot year-round, do not plant trees directly to the south. Even the bare branches of mature deciduous trees can reduce the amount of sun reaching your house in the winter.

Factors to consider in choosing the right shade plant include height, growth rate, branch spread and shape. Shrubbery planted a few feet away from the house will provide extra shade without obstructing air currents. Plants trees and shrubs so they can direct breezes. Don't place a dense line of evergreen trees where they will block the flow of cool air around or through them.

Vines grown on trellises can shade windows or a whole side of a home. Set trellises away from the wall to allow air to circulate. Placing vegetation too close to your house can trap heat and make the air around your house even warmer. Prevent vines from attaching themselves to your home's facade and damaging its exterior.

Trees and shrubs can be planted to shade the outdoor portion of a home's air conditioner for more efficient operation, but be careful not to obstruct the air flow around the unit.

Be sure your tree-planting sites are safe, both above and below the ground. Check the site for underground and overhead utilities or other obstructions. Avoid planting trees under utility lines. If you need to dig, particularly at a street-side location, contact your local utility company to help locate any underground obstructions.

Throughout the year, the sun's position changes in the sky. Be aware of seasonal sunshine patterns. In North America in the summer, it appears high in the sky, is more intense and shines for more of the day that it does in the winter, when it is lower in the sky. When selecting a planting site, note the size and direction of shadows, especially during the summer months.

Don't overlook low ground cover such as grass, small plants and bushes. A grass-covered lawn is usually 10 degrees Fahrenheit cooler than bare ground in the summer. For best results, try to use native plants that survive with minimal care and require little water. Whatever plants you choose, make sure they can withstand local weather extremes.

Sacramento Shade -- An Example of Community Efforts to Reduce Energy

While landscaping is not an alternative to weatherizing your house, it offers an effective way to increase comfort while lower your energy consumption and costs. That's why SMUD, the Sacramento Municipal Utility District, joined with the Sacramento Tree Foundation in 1990 to encourage local homeowners to plant shade trees. Their community partnership, called Sacramento Shade, has the goal of planting half a million trees by the year 2000. Other communities have similar programs; check with your local utility.

The SMUD program is on track and meeting its goal. More than 170,000 free- five-gallon trees were planted in the first five years, according to Rich Sequest. SMUD's shade tree program manager. "Sacramento Shade is one of the most cost effective energy efficiency programs that SMUD operates," he said.

Thirty-eight species, carefully selected for drought and pest resistance and their ability to grow quickly, are offered by Sacramento Shade. Ten percent of the trees planted so far have been Red Maples, making them the most popular choice of Sacramento homeowners. Next most popular are Chinese Pistaches, a nine percent, and Crape Myrtles, at seven percent.

To take part in the Sacramento Shade program, called SMUD's Conservation Department at 916-445-2020. Leave your name and a phone number, and a community forester will contact you to set up an appointment. This Sacramento Tree Foundation representative will come to your home or business to help you pick the best sites for your new trees. They will recommend the proper species for your location, and will provide as many trees as you need to properly shade your home or business.

Once choices have been made, you can pick up your tree at a demonstration clinic, where you will be shown the proper technique of planting. You do the work. "your labor in digging the hole -- that's the only cost to the homeowner," said SMUD's Sequest.

Sacramento Shade provide deciduous trees not only to homeowners but to businesses and schools as well. The amount of money additional shade will save you on your energy bill will depend on the location and type of your building and on local wind and weather conditions.

For more information on shade trees, Contact the California Energy Commission's toll-free Hotline at 800-772-3300 (toll free in California only), your local nursery, SMUD's conservation department at 916-455-2020, or the Sacramento Tree Foundation at 916-924-8733.

Additional Sources

Home Energy Guide
California Energy Commission
1516 Ninth Street
Sacramento, CA 95814

"Trees, Saving Energy Naturally"
Southern California Edison
800-952-5062

Planting Tips for Trees and Shrubs

Trees and shrubs must be planted, watered and cared for properly to ensure they have a long and healthy life. Follow these important steps:

Dig a hole three or four times the diameter of the plant's root ball. The depth of the hole should be only as deep as the root ball in the center of the hole and deeper outside the root ball. Try to leave the sides of the hole rough, not smooth; smooth walls may "wall off" roots and the plant can become root bound, especially in hard soil. Do not augment the soil with compost of other soil agents, for this will not encourage deep rooting.
Before planting , fill the hole with water to check for drainage. After water drains from the hole, fill it again. The water should drain in 12 hours or less. If it doesn't, select another site.
Remove the plant from the container and gently free the roots from the sides and bottom. If the plant seems root bound, use a knife to "score" the root ball with a series of shallow vertical cuts from top to bottom around its diameter.
Place the plant in the hole so the "crown," the top of the root ball at the trunk of the plant, is slightly higher than the surrounding soil (not more than one inch). This will allow water to drain from the base of the trunk and prevent rotting of the trunk. Fill in around the root ball, lightly compacting the soil just enough to remove any pockets of air.
Use the remaining soil to build a watering basin around the perimeter of the hole. Water slowly to saturate the root ball. Cover the area, except for the root ball itself, with a two or three inch layer of organic mulch to reduce moisture loss through evaporation. Do not cover the base of the truck with mulch as this may encourage rot.
Keep the root ball moist but not soggy for the first few weeks. Continue to water regularly, two or three times a week. Gradually reduce the irrigation frequency and increase the amount of water applied during each irrigation to encourage deep rooting. Drip irrigation is an excellent way to accomplish this.

After a few months, extend the watering basin outward several inches to allow for root spread. During periods of heavy rain, don't allow water to remain around the trunk. You may have to remove a portion of the watering basin to allow water to drain away.
Once a year, apply a time-release type fertilizer to your tree. these small round pellets can be found at your local nursery. Bury one pellet four to 12 inches deep on each side of the tree, beyond the root ball.
Staking is usually a good idea. two sturdy, eight-foot-long redwood stakes work well. Drive them about two feet into the soil beyond the root ball. Place the stakes on opposite sides of the trunk on the east and west sides. Tie the trunk loosely to the stakes in two places, using ties specially designed for trees. The ties should be tight enough for support, but allow the tree to move. Some movement of the tree will actually help strengthen the trunk.
Keep weeds, grass, flowers, ground covers or other plantings well outside the drip line of the tree until is it three to five-years-old and well-established. your tree's growth can suffer drastically by having to compete for water and nutrients with other plants. It will also discourage the tree from deep rooting.

Correctly Watering Saves Water and the Energy Used to Pump It!

Water in the early morning or the evening hours when it's cool and winds are calm. This will help reduce water loss due to evaporation.
Water slowly for long periods of time (drip water is best) to encourage deep rooting. plants will have great reservoirs of soil area for drawing moisture and anchoring themselves. If possible, install a drip irrigation system.
Learn your soil type -- sandy, clay or loam -- and adjust watering practices to apply just enough water for healthy plant growth. Avoid over-watering. More trees dies from over watering than from any other reason.
Water plants and trees at the drip line -- an imaginary line where rainwater would fall from leaves to the ground. This is the ware where feeder roots are most concentrated.
Use a moisture-conserving mulch such as ground bark or other composted material to cool soil and reduce evaporation.

These suggestions can help with your springtime plant. Check your local nursery or qualified landscape architect for more information. Or contact you local utility company's conservation department.


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