Environment & Science
9:00 am
Tue July 17, 2012

City officials ask residents to water stressed street trees

City officials in Holland, Grand Rapids and Ann Arbor are asking for a little help from residents. They're asking people to start watering trees along city streets – the ones between the curb and the sidewalk. 

Kerry Gray is an Urban Forestry & Natural Resources Planner with the City of Ann Arbor.

"Most of the trees are currently really under a lot of stress.  So we would obviously love people to water the street trees but we’d also love them to pay attention to the trees on private property as well."

She says trees need water immediately if you see wilting or curling leaves and if leaves or needles are dropping off.  Newly planted trees are especially at risk.

Here are some guidelines the Ann Arbor city foresters recommend for watering trees:

  • The morning hours are usually the best time to water
  • Slow, deep soakings are better than frequent light watering for both newly planted trees and established trees
  • For newly planted trees and small trees up to 4", a good watering is 10 gallons per inch of tree diameter applied in the mulched area around the tree, once per week.  A 3" diameter tree would need 30 gallons of water (3" x 10 gallons).  Newly planted trees should be watered weekly during the first 3 growing seasons.
  • For established medium trees (5"-12"), a general guideline for watering during prolonged dry periods is 10 gallons of water for every 1 inch diameter, three times per month.  For example, an 8" diameter tree will need 80 gallons of water.  To water, place a sprinkler or soaker hose in the dripline of the tree.  The dripline is the outer extent of the branch spread.  Move the sprinkler/hose around to ensure that all the roots in the dripline are watered. 
  • For large trees (greater than 13"), 15 gallons of water for every inch of diameter, two times per month during prolonged dry periods. A 14" tree would need 210 gallons of water. To water, use the method described above for medium trees. For established trees, do not water within 3 feet of the trunk; this can lead to root rot.
  • In normal precipitation years, mother nature provides the water an established tree needs and supplemental watering is typically not necessary.   

 

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