Keep watering trees through the fall season

Posted: Friday, September 28, 2007

Updated: Friday, December 7, 2007

Watering your trees into the autumn until the ground freezes will increase tree vigor and reduce the chance of winter damage.

This year’s drought, in addition to last year’s dry conditions, has taken a toll on many trees. Like humans, once trees become stressed they are more susceptible to a number of secondary insects, diseases, and disorders. However, watering your trees into the autumn until the ground freezes will increase tree vigor and reduce the chance of winter damage.

Unlike lawns, trees thrive on less frequent, deep watering in order to maintain soil moisture at an optimum level. Consider purchasing a soaker hose or drip watering tape, and a soil probe. The hoses can be positioned around the drip line of a tree and will deliver water slowly over the tree’s entire root zone. The soil probe can be used to take a core from the soil around a tree to see how fast water is moving into the soil. This information will help you decide how long to let the hose run since watering requirements will vary depending on the type of soil you have in your yard.

In order to keep the first eight to 12 inches of soil moist, but not saturated, follow these guidelines.

New trees

(one to four years in your landscape)
  • Water by rain or hose two times a week for the first growing season.
  • Use 1.5 to 2.5 gallons per inch diameter each time you water.
  • For the next two to three years, supply water at least once a week.
  • Water the root area with a radius of three to six feet around a tree’s stem, depending on the size of the tree.
  • Plan for one year of transplant shock per inch of stem caliper. For example, a two-inch caliper balled and burlap tree will be in transplant shock for two years. Plan to water it with about four gallons of water twice a week, when there is no significant rainfall.
  • A layer of wood mulch around the tree’s drip line will conserve soil moisture.

Established trees

(five to 150-plus years in your landscape)
  • Supply water at least once a week.
  • Use 1.5 to 2.5 gallons per inch diameter each time you water.
  • Water around the critical radius of the rooting zone, defined as the diameter of the tree trunk times 1.5 feet.
  • Water around the tree’s entire root zone, not just the area next to the trunk.
  • A layer of wood mulch around the tree’s drip line will conserve soil moisture.