How to Water Lawns in Northern Virginia

Why water the lawn?

Water composes from 75 percent to 85 percent of the weight of a healthy grass plant. It is essential for seed germination, tissue formation, plant cooling, food manufacture, and nutrient absorption and transport.  A grass plant loses the most water under conditions of high light intensity, high temperature, low relative humidity, and windy conditions.  Without adequate water, the grass plant can’t cool itself and becomes susceptible to wilting, desiccation, and death.

How much water does my lawn need?

This varies somewhat depending on grass type.  In general, applying one inch of water per week is the recommendation when there is insufficient rainfall during summer drought.  An inch of water can be measured by marking the side of a tuna or pet food can placed in the lawn.  Remember that if nature provides water by rainfall, irrigation may not be needed.  Nothing is more wasteful (and sure to attract attention for all the wrong reasons) than seeing irrigation running in the rain!  Pay attention to current weather conditions and forecasts in order to use water more responsibly.

How can I tell if my lawn needs water?

A “thirsty” lawn turns from the normal green color to a purple-bluish color.  In these areas the grass blades will not spring back if you walk across the lawn and your footprints will be visible.  This is the first sign of “wilt” and indicates a need for water.

Tips for better watering

  • Deep and infrequent watering maintains a healthy root system and reduces weed infestation (as opposed to light and frequent irrigation, which promotes shallow roots and germination of weed seeds).
  • Applying one inch of water is often difficult to achieve in a single watering given the slow infiltration rate on most Virginia soils.  Therefore, smaller amounts of water applied every three to four days may be required to allow water to enter the soil without causing runoff.
  • Water is best applied early in the day (5:00 to 10:00 a.m.) when evaporation loss is lowest. Afternoon watering is acceptable but wind may affect uniformity.  Night watering minimizes evaporation, but may increase fungal diseases.  Consider that numerous automatic sprinklers all running during periods of high household use (early morning) may place extreme demands on a community’s water system.

Note:  Watering instructions are from Dr. Mike Goatley under Publication 430-010 VA Cooperative Ext 2004