Watering Trees

Trees require water, but improper watering practices can cause serious damage. For instance, overwatering is one of the primary causes of failure in recently transplanted trees. Overwatering forces oxygen out of the soil and results in oxygen starvation of roots. This causes root death and leads to the decline of the tree. The yellowing of foliage, first developing low and on the inside of the tree and progressing to the outer leaves, is an indication of oxygen starvation.

Avoid frequent light watering. This promotes the development of shallow root systems that are susceptible to winter injury and summer heat stress. Water infrequently but deeply (at least 6 to 8 inches) and allow the soil to dry out some between applications. Most tree roots are not very deep (within the upper 6 to 12 inches of soil), and deep roots will receive water if enough is applied to the soil surface. Again, be careful not to overwater established trees and avoid applying water directly to the trunk.

Water with an open-end hose at a rate low enough to keep the water from running off. A quick rule of thumb for watering trees is to water one hour per inch diameter of the tree. Remember, tree roots extend away from the tree at least as far as the tree is tall, and in most cases much farther. Place the hose at or beyond the drip line for the most effective watering.

MULCHING

Mulching around the tree's base reduces soil moisture loss, improves water and air penetration, and keeps soil temperatures more stable. These conditions are helpful for root growth and therefore improve tree vigor. Wood chips, shredded bark, dried grass clippings or pine needles all can be used for mulch. Cover the area with mulch about 3 to 4 inches deep. Avoid mounding mulch next to the tree trunk.