Despite occasional showers in certain areas of southern Colorado, persistent drought conditions have parched the soil over much of the southern part of the state, stressing even irrigated lawns and larger landscape trees. During these periods of drought, homeowners should consider supplemental watering to keep their trees healthy.

“Adequately watering your trees is the best way to ensure optimum growth and vigor during the summer months,” said Donna Davis, urban and community forestry specialist for the Colorado State Forest Service. “Drought-stressed trees become susceptible to root and branch die-back and subsequent insect and disease problems.”

All of southern Colorado is currently experiencing some form of drought, with it being “severe” and “extreme” across nearly all of southeast Colorado, according to the latest data from the National Drought Mitigation Center. It is especially important to provide supplemental water to trees this summer given the additional stress and injury many trees experienced during cold snaps in April and last October.

The CSFS offers the following tips to keep trees healthy during summer drought:

• Mulch. Mulch is an inexpensive solution to retain soil moisture and save water. Apply four inches of organic mulch onto bare soil within two to three feet from the base of the trunk (removing any grass first, if necessary). Do not allow the mulch to directly contact the trunk.

• Water a wide area. Tree root systems may spread much wider than the height of the tree, with most absorbing roots in the top foot of soil. Apply water to soak the entire area underneath the full span of a tree’s branches.
• Water slowly. To ensure soil penetration, use a deep root fork (inserted eight inches or less), soaker hose on low setting or soft spray wand to apply water gradually to the full area.
• Keep the yard green. Trees located in irrigated lawns generally do not require additional water, as long as the area surrounding the tree receives adequate moisture. Conversely, a dry, yellowish yard means the roots of any trees present are also dry.

• Provide enough water. For trees 1-3 inches in diameter, apply 10 gallons of water for each inch of tree trunk diameter once a week. For medium-sized trees, those 4-9 inches in diameter, apply 10 gallons of water for each inch of trunk diameter three times a month. For larger trees over 10 inches in diameter, apply 15 gallons of water for each inch of trunk diameter twice a month.
• Focus on new and non-irrigated trees. Water newly planted trees and seedlings more frequently than once a week, following the rates listed above, as they have less-extensive root systems. To avoid stress during drought conditions, trees that do not receive water from sprinkler systems or irrigation can also benefit from additional water.

Visit http://csfs.colostate.edu for more tips on tree watering, planting and general care.