Knowing how and when to water could be the most important landscape management decision. Too much water and too little water will cause plant death. Dry conditions can occur across North Carolina during most growing seasons so that supplemental watering is usually necessary.
Although mechanical moisture meters are available, the best measuring device is the human touch. As a general rule, plants should be watered when the top inch or two of soil feels dry. The length of time between waterings will depend on temperature, wind, humidity, rainfall, and exposure. The type of soil or growing media and the way the plant was set will also influence the plant's need for water. Plants that require good drainage are sometimes planted on a mound built mostly of organic matter. This planting situation will require much more frequent watering than the plant set at grade level in clay soil.
Under normal conditions, clay soils dry out in 15 to 20 days; loam in 7 to 12 days, and sandy soils in 3 to 5 days. Most newly planted trees and shrubs should be watered once every 5 to 7 days during the establishment period. After the plants are established, supplemental water will not be as critical. When irrigating the landscape, water should be applied so that it soaks in and little run-off occurs.
In compacted soils, a drip irrigation system or soaker hose may be recommended. A good organic mulch layer will also minimize run-off. Individual trees and shrubs should be planted so that an earth saucer can be formed around the outside area of the root ball. This 4- to 6-inch dam-like structure will allow the area to be filled with water and the water can slowly soak down into the root zone area and become available to the roots. A thorough soaking can be accomplished with minimum run-off.
Most plants will show immediate signs of drought stress: wilting of the foliage, dull color of foliage, and even dropping of foliage. Water should be applied to the root systems at first sign of stress. If properly watered, the plant should respond positively within a 24-hour period.
Return to: Cultural Practices