Troops, let's talk about watering your turfgrass. As in mowing, I said, "High and slow." With watering, it is "Deeply and infrequently." 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 nutrient 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.
Are some grasses more drought tolerant?
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 CONUS. Consult ME or your local agriculture 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. Augustine grass, and centipedegrass actually prefer warm conditions and can tolerate most drought conditions due to their deep and extensive root systems.
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, 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.
What about too much or too little water?
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 region, consider using them because they can better withstand most drought conditions.
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 are visible. “Foot Printing” 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 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 soils in the mid-Atlantic region. 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 (0500 hours to 1000 hours) when evaporation loss is lowest. Afternoon watering is authorized 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 (like early in the morning) may place extreme demands on a community's water system. Water the lawn, not driveways, sidewalks, or roads, by adjusting sprinkler heads. Mow your grass at the right height during the summer (HIGH!). Longer grass blades increase the depth of the root system, shade the soil, and help drought tolerance.
So, troops, make it happen. Watering for 30 minutes each day at noon is not the solution. Water deeply, real deep, to the maximum root depth. Water the daylights out of your lawn (if you can afford it). Then wait for signs of drought stress. Then water it again at that time. Frequent, light waterings is a no go at this station.