Year-round gardening: Benefits of an urban forest |

Much has changed in El Paso County over the last couple hundred years. A big city grew up where none was before, and people planted trees in what was formerly mostly a prairie setting.

Trees have a critical role in the urban environment. One of the primary benefits is providing shade. With all the concrete and asphalt, urban areas build up significantly more heat than surrounding areas, called an “urban heat island effect.” This effect is exacerbated by rising summer temperatures and prolonged heat waves, making the shade of trees increasingly important. Trees lower surface and air temperatures through shade as well as evapotranspiration. Shaded surfaces might be 20 to 45 degrees cooler than the peak temperatures of unshaded materials.

Collectively, what we plant in our yards can make a big difference tincooling the city or your neighborhood. Think how much more pleasant it is to walk along a shady street than one blasted by the sun.

Urban trees also contribute to cleaning our air, filtering our water, controlling storm water, providing habitat for birds and other wildlife and increasing property values.

However, it’s not easy being a tree in Colorado, so we need to make sure that we do everything we can to maintain mature trees that we do have in addition to planting new ones. People often don’t water mature trees, thinking that they don’t need it, but as the climate warms, trees are increasingly under stress. Apply 1 to 2 inches of water every two weeks in the growing season out to the drip line, and once a month in the winter if we don’t get snow. Sprinklers are the easiest method, but there are other options:

Ideally, we would have a diversity of trees in the urban forest so that if diseases or pests break out (as with the emerald ash borer, which has yet to be detected in the county), we don’t lose a significant number of trees. So look around your neighborhood, and plant something different than what you see. Some good tree choices include hackberry, Kentucky coffee tree, catalpa, hawthorns, Texas red oak and crabapples.

It is preferable to plant in the yard (but not necessarily in the lawn) rather than a parking strip narrower than 5 feet wide, because it is hard to properly water such a narrow area, and the roots might not have enough room. If you plant a tree in the parking strip, make sure it is on the approved street tree list,, and take overhead powerlines into account.

Fall is a great time to plant trees, so get out there and add to our urban forest.

Submit gardening questions to or call 719-520-7684. Find us on Facebook at Colorado Master Gardeners-El Paso County.

Submit gardening questions to or call 719-520-7684. Find us on Facebook at Colorado Master Gardeners-El Paso County.

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