A Guide to Tree Care in Dry Climates

Tips on Tree Watering from Denver Water and the Community Tree Alliance

Sometimes your trees could use a drink. Prolonged dry periods and high winds can dry trees and soil. Watering your trees will help ensure their optimum health.

Tree roots are not like carrots

Tree root systems can spread two to three times wider than the height of the tree. Most of the tree's absorbing roots are in the top 12 inches of soil.

Water should be applied within the drip line (the critical root zone shown at left).

Water deeply and slowly

Apply water so it moistens the soil in the critical root zone to a depth of 12 inches. Water with a deep root fork or needle, soaker hose or soft spray wand. Apply water to many locations under the drip line. If you use a deep root fork or needle, insert the device no deeper than eight inches into the soil.

How much water to apply

May through September: In normal precipitation years, trees located in irrigated turf areas do not need additional water.

Trees that do not receive water from turf irrigation need water based on the trunk’s diameter. Apply 10 gallons of water for each inch of the tree’s diameter each week. For example, a 2-inch diameter tree needs 20 gallons of water weekly. Refer to the schedule below.

During a drought, reduce the frequency and amount of water for larger trees (10 inches in diameter and above) because they have a larger root system that can hold water longer than small and medium trees.

October through April: During prolonged dry periods, water once or twice a month, using 10 gallons of water for each inch of the tree’s diameter. Water only when the temperature is above 40 degrees and there is no snow on the ground.

Mulch helps retain soil moisture

Mulch helps conserve soil moisture. Apply a band of organic mulch 2 to 3 feet from the base of the trunk at a depth of 4 inches. Eliminate turf prior to applying mulch so water is directly transferred to the tree roots. Leave a gap between the mulch and tree trunks to reduce susceptibility to pests and disease. Use a shredded wood mulch material to retain the proper balance of moisture and compact to reduce erosion or movement of the material.

Moisture is needed to avoid disease

Stressed trees are more vulnerable to disease, insect infestations and branch death. Keep an eye out for anything that looks out of the ordinary.