Plant Pathology Infobytes

July 23, 1998
Don't "Over-do" Watering in the Home Landscape

Shrubbery and other ornamentals in the home landscape are using more water than usual as a result of heat stress. During heat stress, injury to azaleas, hollies, junipers, roses, and other woody ornamentals can quickly result through water shortage. Dogwoods and other shallow-rooted plants are also susceptible to this condition.

As a general rule, water at the equivalent of one inch for each week if doesn't rain. Water deeply to encourage deeper root penetration. Don't wet the foliage, and water in the afternoon to give the surface of the soil time to dry during the afternoon. Also, mulch around shrubs and small trees to conserve moisture (this also helps protect from lawn mowers and string trimmers).

How do you know if your plants need water. Another general rule, if you can't detect soil moisture two inches or so beneath the soil surface, your plants need water.

However, while the moisture demands of plants need to be met, don't overdo your watering. The Plant Pathology Laboratory at Mississippi State University generally receives a number of specimens which have rotted roots as a result of overwatering. So it's best to follow the "one inch per week" rule of thumb.

Adding too much water to the root system can create a condition called "anoxia," which means root oxygen starvation from prolonged saturated soils. Frequently, plants suffering from this condition exhibit wilting and dead foliage.

So while it's true that shrubs and small trees do need water, too much of a good thing can be harmful. Practice good watering practices to insure the survival of your shrubs and small trees during tough growing conditions. For more information on maintaining a healthy landscape, contact the County Extension Office.


Written by the late Dr. Frank Killebrew

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