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.
Yes, grasses differ in both their need for water and their drought tolerance. Also seedling or recently established lawns (less than 12 months old) have little drought tolerance. You must consider the proper planting time for the various grasses in order to successfully establish a lawn. Some mature grasses develop deep roots and require less water. However, the most drought-tolerant grasses may not be suitable for all regions of Virginia. Consult your local Extension agent for specific information for your area.
Tall fescue when properly managed develops a deep root system and can be very drought tolerant. However, this advantage is lost if grown on shallow or extremely compacted soils.
Kentucky bluegrass can survive extended drought periods by gradually slowing growth, turning straw colored and entering summer dormancy. Once water becomes available again, it can initiate new growth from the crown of each plant.
Perennial ryegrasses have little tolerance to dry conditions and usually do not persist well in non-irrigated areas.
Fine fescues such as creeping red, chewings fescue, and hard fescue tolerate dry periods quite well due to their low water requirements.
Warm-season grasses such as bermudagrass, zoysiagrass, St. Augustinegrass, and centipedegrass actually prefer warm conditions and can tolerate most drought conditions due to their deep and extensive root systems.
Over-watered lawns frequently lead to excess blade growth, summer fungal diseases, and more frequent mowing. Excessive watering also wastes water and increases the risk of fertilizer and pesticide runoff from the lawn to paved surfaces. This could negatively impact local water quality.
Lawns that receive little to no water from irrigation or rainfall during summer months will go dormant. Grass blade coloring will lighten. Most lawns will recover when water returns. During a severe drought, cool season grasses (ryegrasses, fescues, or bluegrasses) may die and require reseeding in the fall. This may be acceptable to those looking to conserve water during summer months, or may be necessary because of water-use restrictions during a drought. Again, where warm-season grasses are adapted within the state, consider using them because they can better withstand most drought conditions.
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.
|Mowing Heights in Inches for Grass to|
Improve Drought Tolerance in Virginia
|1 to 1.5"||2 to 2.5"||2.5 to 3"|
If you want an in-ground irrigation system, a reputable irrigation consultant will help you design the appropriate system for your lawn and landscape, and will see that you choose the appropriate components to create an efficient and effective irrigation system. If you are selecting portable, above-ground sprinklers, look for sprinklers that keep water close to the ground rather than sending a fine mist or spray high into the air. This will help reduce evaporation as well as keep the water on the lawn.
Check for uniform water distribution and overlap with any irrigation system by placing five broad, wide-mouthed cans diagonal to the sprinkler at distances of approximately 20, 40, 60, 80, and 100 percent of the maximum throw of the sprinkler(s). Collect the output, note how long you ran the system, and the average depth of water collected in the cans. This test will do several things for you. First, it will help you diagnose and prevent either dry or saturated areas that can lead to an unhealthy turf. Second, it will allow you to determine irrigation application rates so that you will know how long you can (or want) to run your irrigation to deliver a desired amount of water to your lawn.
For instance, assume you have determined, (or your Extension agent has recommended) that it is necessary for your turf to receive one inch of water per week to perform its best during the hottest, driest months of the year. By using the can collection system described above, you have determined that you need to run your system 60 minutes to deliver one inch of water. However, you also notice that at about 30 minutes into the irrigation event, there is significant puddling on your lawn, telling you that your soil is not accepting the water as quickly as it is being applied.
By knowing what your system is capable of delivering, and paying attention to how the soil accepts the applied water, you can develop a responsible irrigation program in which you run your sprinklers for no longer than 30 minutes per irrigation event in order to avoid puddling and the undesired loss of water due to surface drainage. This will provide a half inch of water and you can now schedule two irrigation events during the week in order to deliver the desired volume of water. Such a strategy maximizes the efficiency of water use and promotes a healthy turfgrass system at the same time.
Remember that what we do to our lawns and landscapes affects local water quality and that of the Chesapeake Bay. Contact your local Virginia Cooperative Extension office and speak with an Extension agent or Master Gardener volunteer for more advice and information on upcoming lawn and landscape classes and seminars in your area.
Funding for this publication provided in part by the Virginia Water Quality Improvement Act.
Original authors: Marc Aveni, Extension agent, Prince William County; David Chalmers, Extension agronomist, Virginia Tech; and Richard Nunnally, Extension Agent, Chesterfield County
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
May 1, 2009