Outdoor Water Conservation

As most locals know, periods of drought are common on Colorado's Front Range. Trying to grow trees in a semi-arid, prairie landscape is challenging enough, without the rigors of an extended drought. The City of Westminster offers several tips on how to keep trees and landscaping alive during drought.

Drought stress may not kill a tree outright, but may set it up for more serious secondary insect and disease infestations. Symptoms of drought injury to trees can be sudden or take up to two years to surface. Here are some signs of drought injury:

• Typically leaves may wilt and scorch, fall early in the season and make the tree appear thin and sickly.
• Drought stress in evergreen trees may exhibit as brown needles at the treetops and ends of lateral branches.

What can we do to preserve the health of our trees when water restrictions are common and water conservation is critical? Follow these tree maintenance procedures during droughts to significantly increase a tree's chance of surviving.

When planning a new landscape, use more drought-tolerant and native plants, or Xeriscape. Once established, native grasses, flowers and shrubs need minimal amounts of moisture and don't require elaborate, water-wasting irrigation systems. Drought-tolerant tree species also exist and can withstand our dry climate and drought conditions.

For more information on low-water landscaping and gardening, including lists of plants that thrive in the local climate, visit the following:

Green Industries of Colorado (GreenCO) 
Denver Water Xeriscape pages 
Plant Select

Remove water-loving bluegrass from the base of the tree or shrub out to its dripline, either mechanically or with non-selective herbicides (such as Round-Up). Be careful not to damage the tree's surface roots if mechanically removing the sod. Replace the grass with two to four inches of wood chip mulch, which will reduce competition for water, keep the lawn mower and weed-eater from damaging tree bark, insulate the soil from temperature extremes, add nutrients to the soil, improve soil structure, aeration and water penetration, and will help retain moisture in the soil for longer periods between watering and rainfall. Wood chip mulch is available to Westminster residents free of charge through the city's limb recycling program at Standley Lake Regional Park.

Young or newly planted trees and shrubs require more frequent watering than mature plants. Drip irrigation systems are efficient at applying the proper amounts of moisture, while not wasting large amounts of water that aboveground spray irrigation systems do.

If watering with spray heads, water for short durations in the early morning to limit run-off, evaporation and over-watering. Watering every two to three days during the summer and once monthly during the winter is critical for new plants to establish. Check soil moisture levels frequently with a trowel or pointed tool and only apply water when soil conditions warrant.

Mature trees and shrubs need less frequent watering and can withstand drought conditions better than new plants. However, drought injury can take longer to appear in them. Apply water every three feet within the tree's absorbing root zone, which generally extends from just within the tree's canopy to beyond its dripline. Soak the tree with sprinkler systems or manually by hose once a week during the summer and once per month in the winter. Apply the moisture slowly to allow deep soaking and to avoid run-off, approximating about an inch of moisture per week.

Minimize fertilizer applications during time of drought, as these may stimulate too much leaf area on the plant for the root system to maintain during periods of limited soil moisture.

Properly prune trees and shrubs during droughts. Leaving broken, dead, insect-infested or diseased branches can further weaken a tree during drought and set the tree up for deadly secondary insect and disease problems.

Following these guidelines will help preserve the most valuable assets to our landscapes -- our trees and shrubs -- and also will meet guidelines for water conservation during drought periods. For more information, contact your local garden center, county extension office or the City of Westminster Parks Division.