Watering

6 August 2007

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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According to the U.S. Drought Monitor, as of July 26 about 70% of Virginia, including our area is in moderate drought. This is up 5% from last week. Situations like this call for precautions regarding water use and voluntary conservation has already been requested by local governments. Proper use of water is essential for both the protection of our water supply and the health of our plants.

A healthy plant is 75 percent to 90 percent water. Water is used for photosynthesis, transportation of nutrients and sugars to various parts of the plant, and to keep the plant erect to get as much sunlight as possible. Adequate water is especially critical during the first few weeks of growth, while plants are becoming established and building their root systems.

Depending on the type of soil you have, most vegetable gardens and flower beds need about 1 to 2 inches of water per week applied at one time either in the form of rainwater or irrigation. One thorough watering each week that wets the soil to a depth of 5 to 6 inches is ideal. To determine the depth of soil moisture, dig into the soil a few hours after watering to determine how deeply normal watering wets the soil. If it is greater than 5 to 6 inches, shorten your watering time. The amount required varies with the nature of your soil.

Do not water again until the top few inches of soil begin to dry out. Frequent, light watering will encourage shallow rooting that will cause plants to suffer more during drought periods, especially if mulches are not used. On the other hand, too much water, especially in poorly drained soils, can be as damaging to plant growth as too little water; it deprives the roots of oxygen needed to grow. Keep a rain gauge near your garden so you will know when to supplement rainfall with irrigation water.

Because annual flowers and most vegetables are replanted every year, they will often have high water needs in order to get established. In addition, vegetables need more water during the development of the edible part of the plant (fruit, pod, head, seed, etc.).

A List of Tips

• Adding organic matter improves the ability of soil to use water more efficiently. In clay soils, organic matter improves drainage, permitting deeper and faster water penetration.
• Deeply preparing the soil (6 inches or more) promotes rapid plant establishment and reduces the period of high water needs. The deeper the roots penetrate the soil, the greater access to water the plant has.
• Buying plants with well-developed root systems that are vigorous, but not too large for their pots insures faster plant establishment.
• Mulching helps reduce weeds that compete for water and it reduces evaporation of water from the soil. Organic mulch is preferable in most situations as it will contribute organic matter to the soil.
• Consider installing rain barrels to collect water that runs off your roof.

There are numerous options for applying water to plants, each with its own specific use. A sprinkling can is most valuable as a decorative item around the house. However, it is also useful in the garden for gently watering young plants when you have only a few. Likewise, it is useful for watering a few container plants on a balcony that does not have access to a faucet.

A garden hose with a fan nozzle or spray attachment is valuable for watering newly emerging seed, young transplants, or other plants that need frequent, shallow watering. Deep penetrating watering is nearly impossible to achieve with a hand-held hose.

A portable lawn sprinkler provides slow overhead watering and a wonderful place for kids to play in the hot summer. Unfortunately, much of the water from a sprinkler is lost to evaporation or runoff as it lands on a driveway or street.

A soaker hose applies water slowly and directly to the soil. A soaker hose is simply laid at the base of the plants and can be moved around the garden. Properly used, a soaker hose eliminates many of the problems of the overhead sprinkler, such as loss to evaporation and diseases caused by wet foliage.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.