Lawn Care/Basics for Homeowners-Lawn Care/Watering
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Water
is essential to a healthy, dense, actively growing lawn. It can, however, be wasted
or wrongly applied, so as to do more harm than good. Sometimes overwatering may
cause more damage than a lack of water. Sometimes frequent but light watering
will benefit weeds far more than turfgrass.
It is likely that only a minority of homeowners have a clear idea how best to
use the water they have.
The single most important principal of watering in most of the United States is this: Water Deeply and Infrequently. This will meet your lawn's immediate needs and encourage its roots to grow deeper.
A rule of thumb for the Midwestern United States would be one or more inches of water, applied once per week at a time between 4:00 and 8:00 A.M. Know the application patterns and rates for your sprinkler and adjust watering times and locations according. Hand-held hose-end sprinkling as seen below is virtually useless.
In certain cases and areas, local conditions may dictate a particular watering pattern. This is obviously a vast difference between the Pacific northwest and Nevada or southern Arizona. For a more detailed and localized discussion of watering practices and needs, see:
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(Delaware)Lawn Management for Water Conservation: (Georgia) Irrigation for Lawns and Gardens (Illinois) Watering Lawns the Right Way (Kansas)Watering Your Lawn (Kentucky)Home Lawn Irrigation Watering Your Lawn (Nevada)Your Lawn and Water (Nevada)Scheduling Turfgrass Irrigations: Worksheets 1-3 |
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Only about 1 to 2% of the water taken up by turfgrass plants is used for growth and development. Most of the water taken up by turfgrass plants is used for evapotranspiration to regulate plant temperature. Energy from the sun that accumulates in turfgrass leaves is dissipated during evapotranspiration when water in the leaves is converted to water vapor, reducing the heat load in the plants. The water vapor passes into the atmosphere through very small openings in the leaf surface called stomata.
Turfgrass water use needs are determined by weather conditions, turfgrass species and management practices. Turfgrass water use is expressed as depth of water per unit of time, such as inches per day or inches per week.
It is easy to overwater a turf area. Some potential
consequences of overwatering include increased crabgrass pressure, increased
disease incidence, shallow rooting, waste of a valuable resource, and higher
water bills. When watering a lawn, it is best to err on the dry side rather
than to be guilty of overwatering.
Rooting depth governs how deeply a turf stand should be irrigated. Water should penetrate the soil profile to a depth slightly below the bottom of the root zone. Turfgrass plants take up water only where roots are located so wetting to a depth slightly below the bottom of the root zone encourages roots to to grow deeper to seek water. Watering too deeply wastes water since roots can not reach it. Likewise, turf should not watered too frequently since a soil profile that is is only wetted to a shallow depth leads to a shallow rooted plant.
Since plants only take up water where roots are located, a turfgrass plant with a deep root system is able to absorb more water than a plant with a shallow root system. Therefore, deeply rooted turf stands need to be watered less frequently than stands with a shallow root system.
Water for a known amount of time, allow the water to soak into the soil for a few hours and then observe the depth of moist soil in comparison to rooting depth, and adjust accordingly.
The amount of water held by soil that is available for plant uptake is determined by soil texture. For example, turf growing in sand will utilize the available water faster than the same turf growing in a silt loam soil and must be watered more frequently. Soil texture also plays a major role in determining how deeply water penetrates the soil profile. One inch of water applied to sand in a single irrigation will penetrate the soil profile approximately 18 inches. One inch of water applied to a clay soil in a single irrigation will penetrate the soil profile approximately 6 inches. Since soil texture has a major influence on irrigation frequency, you should know the texture of the soil on in your lawn.
Turf should not be watered by a set schedule. A set schedule does not take into account the needs of turfgrass plants and may lead to overwatering. For this reason, homeowners with automatic irrigation systems should not use the same irrigation program for the entire summer. The program should be changed according to the needs of the turfgrass plant. Any automatic irrigation system should be set to start for a single irrigation cycle only and then shut off until the turf requires water again.
The frequency of watering will vary from site to site and should be determined by the appearance of the turf. This can be determined because the first signs of water stress in a turfgrass stand are a bluish green color, and footprints remain in the turf after walking across it. Ideally, the turf should be watered at this point. Turfgrasses can easily withstand this much water stress without a decline in turf quality, and there is no real benefit to watering a turfgrass stand before this point.
As the degree of water stress increases the turf will wilt and have a grayish green color. Turf that has wilted should be watered without delay. Wilted turf will recover very rapidly following watering. Severe drought stress will cause the turf plants to cease growing or go into dormancy; the leaves will turn brown and possibly die. Watering at or after the point of wilting or dormancy will help the turfgrass plants survive, but it will take about two weeks until the turf produces new leaves and recovers completely.
Most lawns in the Midwestern will need from 1 to 1 1/2 inches of water per week depending upon weather, soil type, slope, etc. It is far better to apply this amount of water in a single thorough soaking, or two equal applications of water three to four days apart rather than in light irrigations every day. The soil should be wetted to the depth of the deepest root. Daily, light irrigations promote shallow rooting, non drought hardy turf, and encourage crabgrass.
Familiar hose end sprinklers usually apply small volumes of water to a turfgrass area. Therefore, most sprinklers should be left in one location for two to three hours to thoroughly wet the turfgrass root zone. To determine the amount of water being applied by your sprinkler, place shallow, straight sided containers, such as empty tunafish or cat food cans, in a grid pattern around the sprinkler. Turn the sprinkler on for a specified length of time and then measure the water collected in the cans with a ruler. This can be used as a guide in determining the amount of water applied.
Automatic irrigation systems with spray heads that distribute water in all directions simultaneously are capable of applying a large volume of water in 10 to 15 minutes. Automatic irrigation systems with rotary sprinkler heads that have one stream of water are capable of applying the necessary water in 30 to 40 minutes.
In the Midwestern United States the ideal time to irrigate a lawn is from 4:00 to 8:00 a.m. At this time municipal water pressure is usually the highest, there is little distortion of the watering pattern by wind, and the amount of water lost to evaporation is negligible. Although the early morning hours are ideal for watering, this is not a convenient time for most people.
The second best time to water is from 8:00 to 12:00 p.m. Usually distortion from the wind is not a problem at this time and loss from evaporation is slight. A major problem may be lack of water pressure for those using municipal water systems.
A potential problem caused by watering in the early evening hours may be greater incidence of disease. This problem can be reduced by watering only when the turf needs water and by watering infrequently but deeply.
Watering an established turf during midday is not very effective. A large amount of water is lost through evaporation, making it difficult to thoroughly wet the soil. Although not recommended, midday watering does not cause the turf to burn.
Slopes or areas with soil compaction are often difficult to irrigate without the water running off. On these areas it is important not to apply water faster than it can be absorbed. One possible method is to irrigate a slope for a period of time until the water just begins to run off and then stop. Allow the water to infiltrate into the soil and then water the area again until runoff just begins. Repeat this cycle several times until the soil is wet to a depth of six inches.
In extended droughts where a lawn is not watered, the lawn will wilt and the leaves will turn brown. These lawns are not dead; the turf is in a dormant condition. Dormancy is a natural survival mechanism of the turf plants. The leaves are dead but the crown (growing point) and the root system remain alive.
Dormancy is a good grass survival strategy. A turfgrass plant loses water through the leaves. When the leaves are dead, little water is lost which conserves water and allows the crown and root system to remain alive. Turf can survive four to six weeks in a dormant condition without a significant thinning of the turf upon the return of favorable moisture conditions.
After four to six weeks of dry conditions, the dormant turf should be irrigated with 1 to 1 1/2 inches of water in one thorough irrigation. This irrigation will not cause the turf to green up but will provide moisture to help the crown and root system survive. If the dry weather persists, water dormant turf with 1 to 1 1/2 inches of water every four to six weeks. Following the onset of favorable moisture conditions, either through rainfall or irrigation, the turf will develop new leaves and begin to grow actively.
A newly seeded lawn has special requirements. It will need to be watered two to four times a day. The seed bed should be moistened to a depth of 1 to 2 inches but not saturated. As the seed germinates and seedlings begin to grow, it is essential that the new seedlings are not allowed to dry out. Continue to water the seedlings two to four times a day if the weather conditions are dry.
As the seedling turf grows (to two inches in height) and the root system penetrates deeper in the soil, the amount of water applied should be increased to moisten the soil to a greater depth to encourage deeper rooting. Thus the frequency of irrigation should gradually be reduced from two or four times per day to once a day, to twice a week. After the new turf has been mowed two or three times, deep, infrequent waterings become preferable.
A newly sodded lawn also has special needs. New sod should be lightly rolled immediately after transplanting to eliminate air pockets between the soil and sod. This will help prevent the sod from drying out. It will require water one or two times a day.
Sod should be watered so that the sod strip is wet the entire thickness and the soil underneath is moist to a depth of one inch. This will encourage the roots to grow from the sod into the soil below. Overwatering sod is a common mistake. Do not saturate the soil below the sod. Turfgrass roots need oxygen to grown, and this will inhibit roots from growing into the soil.
As sod becomes established and roots penetrate and grow in the soil, gradually reduce the frequency of watering but wet the soil to a greater depth. After the sod has been mowed three or four times, deep, infrequent watering should be practiced.
Taken from the Publication: Irrigation Practices for Homelawns
by Clark Throssell and Zac Reicher.
Text modified and updated for 2003 by Alfred E. Krause
Cooperative Extension Work in Agriculture and Home Economics,
(State of Indiana, Purdue University, and U.S. Department of Agriculture Cooperating)
H. A. Wadsworth, Director, West Lafayette, IN.
Issued in furtherance of the acts of May 8 and June 30, 1914. The Purdue University Cooperative Extension Service is an equal opportunity/equal access institution.