Central Valley Friendly Landscaping
University of California
Central Valley Friendly Landscaping

#2 Conserve energy and protect air quality


You can make a significant contribution to improving air quality in the Central Valley. When you plant shade trees and use hand-powered or electric garden tools, you save money, conserve energy, reduce pollution, and add value and beauty your home and neighborhood.

Plant Shade Trees

tree city shade


  • plants7
    Trees add shade and beauty to our harsh Central Valley climate, and they announce the seasons with their spring flowers, summer fruit, fall color and winter architectural branching.
  • Trees contribute to good air quality by filtering airborne pollutants and converting carbon dioxide into oxygen for us to breathe.
  • Tree roots help capture and absorb rain and irrigation water into the soil, reducing runoff and erosion.
  • Trees along the street buffer street noise.
    shade windows
  • Trees that are planted on the south or west sides of a house conserve energy by shading the house during the summer, reducing air-conditioning use. Deciduous trees lose their leaves in the winter allowing the sun’s rays to enter the house to warm it during winter months, thus reducing heating costs.
  • Trees reduce the heat island effect. Trees provide shade to cool asphalt surfaces, thereby reducing the heat that radiates off those hard
    tree shade2
    surfaces that would otherwise degrade air quality.
  • Trees provide food, shelter, and nesting for wildlife.


  • Plant trees in the garden’s native soil and not in holes where the soil has been amended. By planting a tree in a hole with amended soil, the tree’s roots may stay in the nutrient-rich, friable soil and not grow into the native soil which may be clay, hardpan, or compacted. A major function of roots is to stabilize the tree;
    trunk flare and mulch
     roots of a tree can grow 50% beyond the width of the canopy, so assuring that the roots can survive in native soil is very important.
  • Plant at an appropriate depth – the trunk flare (the spreading area at the base of the trunk that connects with the roots) needs to be at the same level as the ground (grade) or 1-2" above grade.
  • If planted in turf, an area at least 1’ around the base of the tree should be kept free of lawn in order to protect the tree from damage from weed trimmers and lawnmowers.
  • Ideally, a separate irrigation valve will be used to irrigate all the trees on the property. Trees should be watered less frequently but for a longer period of time than lawn or shrubs. Trees that receive only lawn irrigation will have shallow roots because the water does not penetrate deep into the soil. Deeper watering encourages tree roots to grow at a more appropriate depth and supports overall tree health.

 More information on planting shade trees:

Landscape Tree Care site with links to four Shopper's Guides to Landscape Trees, Fresno County Master Gardeners, University of California Cooperative Extension

Tree Fresno Tree Selection Guide (pdf)

SelecTree Tree Selection Site, Urban Forest Ecosystems Institute

Trees and Utilities Quick Tip (pdf) University of California, Agricultural and Natural Resources

Utilities and Tree Selection, Urban Forest Ecosystems Institute

Trees are Good  Tree Selection, planting and maintenance

Use Hand-Powered or Electric Tools

According to a 2010 report by the American Lung Association, the San Joaquin Valley has the fourth worst air quality in the nation. Gas-powered lawn mowers, leaf blowers and other gardening equipment emit high levels of carbon monoxide and pollutants that contribute to the formation of ozone. A traditional gas-powered lawn mower produces as much air pollution as 43 new cars each being driven 12,000 miles according to the U.S. Environmental Protection Agency (EPA). You can contribute to better air quality by choosing to use hand-powered or electric garden tools in your garden.


  • Hand-powered and electric tools need less maintenance to work well. Most electric tools just need to be plugged in, and they are ready to go. There are no oil filters or spark plugs to change and no oil or fuel tanks
     to keep filled. In the winter you will not need to worry about emptying gas tanks when your tools may not be in use.
  • Hand-operated tools are the cleanest, least polluting form of garden maintenance; however, they may be impractical to use in a large garden.
  • Electric tools are a good alternative to hand-operated tools. They are sharper, cut faster, and can fit hard to reach areas, which will save you time. Compared to gas-powered tools, they are less polluting, take less money to operate, and are easier to start.
  • Electric tools do not produce fuel fumes that permeate your clothing or make it uncomfortable to breathe.
  • Electric tools are quieter when operating, which benefits you and your neighbors.


  • Rather than using a leaf blower, sweep green waste and other garden materials back into the landscape or pick it up and deposit it in the  green waste container. Not only will you reduce particulates in the air, but you will also keep fertilizer and other garden debris out of the gutter
    storm drain
    and ultimately out of the storm drain system that helps replenish our groundwater supply.
  • Use electric or hand-powered tools to do garden trimming, mowing, or cleaning. Manual reel mowers have no environmental impact and offer good exercise. They're also good for people with allergies, because they generate the least amount of dust and pollen. Solar and corded electric mowers are the next least polluting, overall, followed by lithium or NiMH battery-powered cordless mowers.
  • When purchasing an electric tool, make sure it is powerful enough to do the job needed in your landscape. Different power levels may be needed for various jobs. Be aware of the minimum and maximum height of the mower to ensure it suits your type of lawn (see Principle #4: Appropriate Lawn Care). Consider lawn obstacles when selecting the width of the mowing row. Keep in mind larger back wheels make it easier to maneuver around trees and up or down slopes.

Webmaster Email: jlcangemi@ucdavis.edu