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Winter Tree Watering Guidelines for Denver

Denver’s tree canopy provides many benefits to our urban environment.Many of the trees in the city are already under stress from last year’s dry winter and this year’s hot, dry summer and will need extra care this year to survive. Previously, trees have been watered when sprinklers were watering the surrounding grass.  This year, with lawn irrigation stopping October 1, trees must be watered by hand or with a deep root feeder or soaker hose.  You may water trees using these methods on any day after October 1st. 

Periods of drought are common on Colorado 's Front Range . This area is naturally a semi-arid, shortgrass prairie that would have few trees without irrigation. Growing trees here is difficult in wet years let alone in drought years. Drought makes growing healthy trees in this region all the more challenging and reinforces the value of a majestic shade tree. Properly placed and maintained trees are an asset to the environment and to our community.

Root systems can spread 2-3 times wider than the height of the tree. Most of the tree's absorbing roots are in the top 12 inches of the soil. Water should be applied within the dripline (see below). Water deeply and slowly, moistening the critical root zone to a depth of 12 inches. Methods for watering include a deep root fork or needle, soaker hose or by hand with a soft-spray wand. If using the deep root fork or needle, insert the device into the soil NO DEEPER than 8 inches. 

v     Water deeply and slowly. Apply water so it moistens the critical root zone to a depth of twelve inches. Methods for watering include a deep root fork or needle, soaker hose or soft spray wand.   Apply water to many locations under dripline.   If a deep root fork or needle is used, insert the device no deeper than eight inches into the soil.  

v     How much water should I apply? As a general survival rule, apply ten gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree will need twenty gallons per watering. Use a ruler to measure your tree’s diameter. 

v     When should I water?  Fall and winter watering, October – March, one to two times per month, depending on weather, temperature and soil conditions.  Spring and summer watering, April – September, three times per month, depending on weather and watering restrictions.  

v     Mulch helps conserve soil moisture.  Apply organic mulch within the dripline, at a depth of four inches.  Leave a six-inch space between the mulch and trunk of trees. Mulch materials may include wood chips, bark, leaves and evergreen needles.  

v     Consistent moisture is needed.  Drought stressed trees are more vulnerable to disease and insect infestations and branch dieback. Keep a watchful eye for anything that looks out of the ordinary.


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Watering times (in minutes) once or twice per month

Temperature and Weather Dependent ( >40 degrees, no snow cover)

tree watering methods and time needed for each (23882 bytes)

Photo: Judy Sedbrook

Images and Information: Denver Water

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CSU/Denver County  Extension Master Gardener 2010
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Date last revised: 01/05/2010