Watering your trees

Trees need watering, regardless of season, especially in a drought and even in winter. Trees should be watered thoroughly and regularly. Here are some general rules for watering.

• The best time to water is morning. Foliage that stays damp overnight is susceptible to fungal diseases.

• Water thoroughly once a week when rainfall is less than one inch per week. You can buy a rain gauge or use a coffee can to estimate rainfall. You can also use indicator plants: impatiens, ajuga, or coleus planted in the root zone will wilt dramatically when the water level is low.

• Water slowly to allow time to soak in. A good rule of thumb is to water one hour per inch diameter of the tree. Water at least six to eight inches deep, then allow time for the soil to dry out. Use an open-end hose with low water pressure to prevent the water from running off. Don’t apply water directly to the trunk.

• Don’t get carried away! Too much water is almost as bad as too little. Overwatering starves roots of oxygen and harms the tree. Too-frequent watering creates shallow root systems that can be damaged by summer heat stress and winter injury.

• Use mulch. Pine needles, grass clippings, shredded bark, or wood chips in a layer three to four inches deep reduce water loss, improve penetration, and stabilize soil temperatures. Leave a ring of open space around the trunk so that mulch doesn’t touch it.