This summer, water trees and shrubs the right way

This article has been updated. Please check our website for the most recent story.
Last Updated: 
July 2, 2007

EUGENE - Improper watering – too much or too little – may be a leading cause of problems with fruit trees and other woody plants in the home landscape during the summer.

“Over-watering literally drowns the root system of a plant,” said Ross Penhallegon, horticulturist with the Oregon State University Extension Service. “Under-watering dehydrates the root system and causes it to die of thirst. It’s easy to over-water plants grown in heavy clay soils and to under-water those grown on sandy, well-drained soils.”

Plants stressed by too much or too little water are also more susceptible to attack by harmful insects and diseases.

Most water-related problems with fruit trees and ornamental shrubs can be eliminated by making simple changes to your watering practices. By knowing how to water, when to water, and how much water to apply, your irrigation practices can be fine-tuned to provide just enough water for best plant growth.

Avoid overhead watering of woody trees and shrubs.

“Overhead sprinkler irrigation may be good for the lawn, but it is not an ideal method for watering fruit trees and shrubs,” warned Penhallegon. “Frequent wetting of the leaves with overhead irrigation provides an ideal environment for the spread of scab, leaf spot diseases, mildew and other fungal and bacterial problems.”

The best way to water trees or shrubs is with the old tried-and-true garden hose. Let the water soak into the ground around the base of each plant.

A soaker hose, another option, is a good way to water a shrub or perennial bed. They operate at low pressure and deliver a uniform volume of water throughout the bed without wetting the leaves.

Trickle or drip irrigation systems, available in most garden stores and mail-order catalogs, are ideal for plants grown outdoors. Most are economically priced, easy to install and can be operated from standard outdoor faucets.

Each of these methods are much more efficient than overhead watering.

Newly planted shrubs and trees require more frequent watering than established plants. A thorough soaking each day during the first week, then twice a week for the following four to six weeks, is the best prescription for fruit tree and shrub establishment.

During the summer season, established plants in heavy soils may require water once a week. In sandy soils, a thorough soaking twice a week should be sufficient.

Deep, thorough watering encourages deep rooting and healthier trees and shrubs, in the long run.

To check how well your irrigation system is working, dig small holes near the tree with a shovel to see how deep the water has infiltrated. Mulch, such as bark or compost, spread three inches thick over the surface of the soil around the tree or shrub will conserve moisture and reduce water requirements. Mulching will also maintain a more uniform soil moisture level, thereby minimizing plant stress.

Author: Carol Savonen