Magazine article Sunset

Smart Trees for Fall Planting

Magazine article Sunset

Smart Trees for Fall Planting

Article excerpt

The right trees in the right place will give you summer shade, winter sunlight, and energy savings

There's a shade tree revolution going on in the West. The battle cry is "Plant trees to conserve energy." And even though public utility companies - striving to reduce energy consumption - started the revolution, Westerners are joining in on a family-by-family, house-by-house basis.

Why? Because tree-shaded houses stay cooler, naturally, than unshaded houses. And because energy is a resource that is bound to become even more precious and more expensive in the future.

But trees do more than provide shade. They beautify houses and neighborhoods, increase property values, create refuge for wildlife, and reduce air pollution. And throughout much of the West, October is the ideal time of year to plant them.

To help homeowners choose and plant trees, Western cities from Tucson to Fresno have started their own shade tree programs (see page 72 for resources in your area). In Sacramento, for example, the Sacramento Municipal Utility District (SMUD) joined forces with the Sacramento Tree Foundation to start Sacramento Shade, a program to encourage residents to plant and care for trees. Since 1990, it has been responsible for the planting of nearly 300,000 shade trees.

What Sacramento and other hot-summer cities have learned in their quest to chill out provides a valuable lesson for us all: Cooling your house with trees - the right trees, in the right spots - does save energy.


The path along which the sun travels across the sky from morning to afternoon - and also from winter to summer - determines the best locations for energy-saving trees.

In midsummer, the sun shines on the east side of your house in the morning, passes over the roof near midday, then beats down on the west side in the afternoon. It's in the afternoon, when temperatures are highest, that solar radiation heats the house most and air conditioners work the hardest. Consequently, the west side of your house is the most important side to shade. The east side, where sun can warm the house early in the day, is the second most important to shade.

As fall and winter approach, the sun is lower in the sky and shines more directly on the south side of your house. With cooler weather, however, the sun becomes a benefit rather than a liability. The warmth it provides reduces heating costs, so in most cases you don't want to shade the south side of the house. Even leafless deciduous trees can reduce sunlight falling on the south side of your house by as much as 40 percent. Leaving the southern exposure open also allows you to use solar collectors for heating water or your home.

There are a few exceptions to these rules. In hot, sunny climates (such as in Phoenix or Palm Springs), the weather can be quite warm in spring and fall. Shading the south side of a house in these areas can have some benefits as long as the trees don't block solar collectors. On the other hand, if you live in a cool- or foggy-summer climate (such as in San Francisco or Seattle), any sunshine is a blessing, and planting trees for shade may be a mistake.

In cold climates, a row of conifers that doesn't shade a house can break cold prevailing winds and help save money on heating. But to make the most of solar gain through south-facing windows, avoid planting any trees that would block sunlight falling on the south side of your house.


In most areas, the ideal shade tree is deciduous: the sun can shine through its leafless branches in winter. It should have a fairly dense round to spreading canopy, and reach 25 to 50 feet - anything much larger may be a liability on an average-size lot. Ideally, the tree will spread its limbs wide enough to partially shade the roof.

Small trees are appropriate where space is limited or when you want to shade only a single window. …

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