Home Lawn Watering Guide
Brad S. Fresenburg and John H. Dunn
As much as 80 percent of the water used around the home during summer is for
outside uses. Watering the lawn is the main outside water use. During dry summers,
local water authorities may cut off water for outside use or only allow watering
on certain days. Both measures are necessary and effective means to reduce water
consumption and relieve the strain on city water supplies.
To avoid severe loss of turf and to conserve water, homeowners should manage
their lawns each year in anticipation of water restrictions.
This guide offers cultural practices that will reduce the need for irrigation
while improving the competitiveness and appearance of your lawn.
Quick facts on lawn watering
- Lawns in Missouri may require as much as 1 to 1-1/2 inches of water per
week from irrigation or rainfall during summer to remain green and actively
growing.
- When managed properly, tall fescue requires 25 percent less water and zoysiagrass
requires 50 percent less water than Kentucky bluegrass to maintain a green,
actively growing lawn in Missouri.
- Turfgrasses in Missouri rank as follows in resistance to leaf wilting and
browning during summer dry periods -- bermuda, zoysia, tall fescue, Kentucky
bluegrass, perennial ryegrass.
- During extended periods of summer drought, dormant lawns (browned-out leaves)
containing Kentucky bluegrass, tall fescue or perennial ryegrass should receive
1-1/2 inches of irrigation every two weeks to maintain hydrated grass crowns
and allow for full lawn recovery when more favorable moisture and temperature
return in the fall.
- Deeper roots draw moisture from a larger volume of soil and therefore require
less supplemental irrigation.
- Taller grass has deeper roots and a lower tendency to wilt.
- Taller grass provides shading of the soil surface and reduces lethal temperatures
near the base of grass plants.
- Lawns mowed weekly at a taller mowing height are less likely to be scalped.
Scalped lawns lose density and have shallow root systems.
Learn to read a lawn and know when to water
Purple-blue wilting leaves, footprints that stay, and folded or rolled leaves
are signs that lawns should be thoroughly watered if grasses are to remain green
and actively growing.
Turf water use rates are high during sunny and windy days with low relative
humidity. In situations where lawns are not watered and rainfall is limited,
grasses first show symptoms of wilt and later turn completely brown.
When soil lacks moisture, grass blades first turn bluish-purple, indicating
plant wilt.
Another early sign of insufficient water in the plant occurs when footprints
remain in the lawn for several hours. Leaves with plenty of water quickly return
to their rigid upright shape, while leaves lacking water will remain trampled
for a period of time.
Leaves also may be folded or rolled lengthwise along the blade, indicating
a lack of plant water.
If high temperatures and dry conditions continue without rain or irrigation,
the above-ground portion of grasses will turn entirely brown and die. Grasses
are said to be dormant during this browned-out stage, since the lower portion
of the plant usually remains alive but not growing. Thorough watering will bring
the lawn out of dormancy and new growth will resume from the below-ground base
of grass plants.
Even though grasses are dormant, watering restrictions that result in extended
dry periods can cause large ground cracks, severe soil drying, and excessive
loss of turf cover even when watering is resumed later in the summer or early
fall.
Summer dormancy of grasses is a mechanism that helps a lawn survive, but
it does not guarantee that a lawn will fully recover from the browned-out stage.
Dormant lawns should receive at least 1 inch of water every two or three
weeks during summer to prevent complete turf loss. Grasses may not show a noticeable
greening, but that amount of irrigation should be sufficient to hydrate the
lower plant portions and increase the recovery once adequate moisture is available.
Wet wilt is another type of wilt to look for. Wet wilt occurs when the soil
is obviously wet, but the root system is not able to keep pace with the water
demands from the atmosphere. The curling of leaves from wet wilt looks very
similar to wilt caused by lack of soil moisture. Waterlogged lawns that have
a shallow root system are susceptible to wet wilt. Do not add more water when
lawns are wilting and soil moisture appears to be adequate; it will only aggravate
the problem by starving the root zone of oxygen.
Prepare for a drought
Management practices in the fall and spring determine the drought tolerance of
the lawn in summer. To reduce the need for irrigation, your lawn management program
should maximize root volume and depth in preparation for summer drought. By the
time summer rolls around, there is little you can do to help a lawn except mow
and irrigate properly.
The following lawn care tips will help reduce the need for irrigation and
increase the chance of surviving summer drought.
- Avoid the temptation to irrigate in spring just to get grass growing. Allow
it to green up naturally. Mow frequently and avoid scalping. Do not begin to
irrigate until dry conditions of early summer cause obvious turf wilt that
lasts for more than one day.
In the spring, atmospheric water demands are low
and moderate wilting of turf does not damage the lawn. If in the spring the
soil is allowed to dry slightly and the grass to wilt some, a deeper and more
hardy root system will develop. Such a root system will be necessary to reduce
the need for summer irrigation and to survive drought conditions or when city
water restrictions are imposed.
- Mow grass as tall and as frequently as possible with a properly sharpened
blade to produce a dense cover with a deep root system. Taller grass has a
deeper root system that draws moisture from a larger volume of soil and results
in less need for irrigation.
Grass height should never be less than 2-1/2 inches
after mowing. Mow frequently enough so that clippings are 1 to 1-1/2 inches
long. Raise the mower height if grass has grown too tall since the previous
mowing. A lawn mowed at heights of 3 to 3-1/2 inches will have a better chance
of surviving prolonged drought and water restrictions.
Most homeowners mow lawns
once a week regardless of the mowing height. Taller mowing heights are less
likely to cause turf scalping, especially when grass leaves are rapidly growing
in the spring. Dull mower blades and scalped turf result in an unattractive
lawn that too many homeowners try to correct with over-irrigation.
- Apply nitrogen fertilizer to cool-season grasses (Kentucky bluegrass, tall
fescue and perennial ryegrass) primarily in the fall.
Some nitrogen may be applied
in the spring if the lawn is sparse and bare soil is visible. Avoid summer
application of nitrogen. Nitrogen fertilizer applied in the spring and summer
causes additional leaf growth, which uses stored plant energy that normally
would be used to produce roots needed for water uptake during summer.
- Test the soil to ensure an adequate amount of phosphorus and potassium.
Additional applications of potassium -- one pound of K2O per
1,000 square feet -- in April and again in May or June will also improve
the summer performance of lawns.
- Core aerify tight soils and thatched turf in the fall or spring to increase
water and air movement into the soil. This builds better root systems. Avoid
summer coring in the absence of water, since it may cause excessive drying
and drought stress.
- Limit thatch removal by power raking or verticutting to fall or early spring
or fall, since water demands are low and turf recovery is rapid. Do not severely
power-rake lawns in the late spring or summer or they will require excessive
irrigation to remain alive. When necessary, severe power raking and seeding
should be done in September.
- Select grasses that require less summertime irrigation to remain attractive.
Zoysia is a warm-season grass and tall fescue is a cool-season grass. Both
are noted for the ability to make an attractive summer lawn with less irrigation.
Select a sprinkler that best fits your needs
Automatic irrigation systems with pop-up sprinklers are often associated with
excessive irrigation. This is not necessarily true, since properly designed and
operated systems supply water uniformly over an entire area without wasted runoff.
Missouri soils generally have low water infiltration rates. Automatic controllers
can be set to supply several short cycles so that the total amount of water
desired is supplied without runoff.
The most common type of watering occurs with hose-end sprinklers. Some studies
have shown that the average homeowner applies 2.5 times the amount of water
that is required for turf growth when using hose-end sprinklers.
There are several types of hose-end sprinklers (Figure 1). Select one
that best fits your size and shape of lawn and then operate it efficiently.
All hose-end sprinklers can be attached to inexpensive timers that can be used
to shut off unattended sprinklers and avoid over-irrigation.
How much water to apply
Once you have decided on the best sprinkler for your size and shape of lawn,
you must decide how long to operate a sprinkler in a certain location. This is
best achieved by knowing how many inches of water your system puts out in a certain
amount of time. To do this, place shallow, straight-sided containers (tuna cans
work well) or rain gauges in a grid pattern around the sprinkler. Operate the
sprinklers (use overlapping patterns where needed) for a given amount of time
and measure the amount of water captured (Figure 2).
Measure the depth of water in the cans with a ruler or read directly from
the rain gauges. Then use the following example to determine your water application
rate in inches per hour. For example, a sprinkler operated for 45 minutes that
delivers a quarter-inch of water has a delivery rate of one-third of an inch
per hour.
An alternative approach would be to measure the area that your sprinkler
pattern covers and the length of time it takes to fill a one-gallon container
directly from the sprinkler. For example, a sprinkler that covers 235 square
feet and takes 1 minute and 15 seconds to discharge one gallon of water has
a delivery rate of one-third of an inch per hour.
In the above examples, sprinklers should be operated approximately three
hours in each location to supply one inch of irrigation water per week.
Most soils in Missouri will take in only about 1/2 inch of water per hour.
If your sprinkler system delivers more than that amount, move it to a different
location more frequently, after each time 1/2 inch of water has been applied.
Repeat the process until the full amount of water desired has been applied.
Rotary sprinklers that are set to deliver a half or quarter sprinkler pattern
will discharge two or four times the amount of water on a given area. Operate
rotary sprinklers with half patterns for half the amount of time and sprinklers
with quarter patterns for one-quarter the amount of time.
The utility water meter connected to your home can also be used to check
how effectively water is being applied. It accurately measures water in cubic
feet. When no other water is being used in the home, water a known area for
a set amount of time and use these conversion factors to determine your water
application rate. Some helpful facts to have are:
- 624 gallons (83.3 cubic feet) of water are required to apply 1 inch of water
on 1,000 square feet of lawn.
- 7.48 gallons = one cubic foot of water.
Once the decision has been made that a lawn has sufficiently wilted and irrigation
is needed, supply enough water to last a week. Depending on the type of sprinkler
and soil water infiltration rate, several sprinkler changes may be required
over a two- or three-day period to supply the amount of water desired.
If no rainfall occurs, continue to irrigate on a weekly schedule. If rainfall
occurs, delay the next irrigation until symptoms of wilt are present. Even though
water application is discussed on a weekly basis, it is not crucial that water
be applied every seven days. Keep the application schedule flexible and irrigate
based on the determination of lawn wilting and soil moisture.
Use the following table to determine the amount of irrigation that will be
needed for your lawn situation.
Table 1
Approximate lawn water requirements
| Lawn type |
Green Turf1 |
Dormant Turf2 |
| Perennial ryegrass |
1.5 inches of water per week |
1.0 inches of water per week |
| Kentucky bluegrass |
1.2 inches of water per week |
0.7 inches of water per week |
| Tall fescue |
0.8 inches of water per week |
0.5 inches of water per week |
| Zoysia or bermuda |
0.5 inches of water per week |
0.2 inches of water per week |
| Buffalograss |
0.3 inches of water per week |
0.2 inches of water per week |
1Lawn remains green and growing
2Lawn may turn brown, but will not die
Once the decision has been made to irrigate, use the above recommendations
to guide irrigation scheduling and how much water to supply. Should puddles
or runoff occur before the total amount of water is applied, stop irrigating
and resume only after the ground has absorbed the free moisture. Lawn areas
that are moist, firm and have no visible water are ready for a repeat irrigation
cycle. Areas that are soft and produce squashy footprints when walked on are
not ready to receive additional irrigation.
A day after watering, check a few different locations in the yard to determine
how well your irrigation program is distributing water in the root zone. With
a shovel, cut a slender 2-inch wedge 6 to 8 inches deep. This wedge of soil,
roots and turf can be replaced easily without damage to the lawn after inspection.
Estimate the moisture content at different depths in the soil profile by
pressing together a golf-ball-sized amount of soil. If drops of water can be
squeezed from the soil ball, you may be irrigating too much or too often. Soils
that hold together without crumbling and appear moist have been irrigated properly.
Soils that appear dry, dusty and do not form a ball when squeezed have not received
enough irrigation or the water is running off the surface of the lawn and not
into the root zone.
Adequate soil moisture at 6 to 8 inches deep is sufficient to maintain grasses
during the summer. A foot-long slender screwdriver pushed into the ground in
several locations can also give a quick assessment of the moisture condition
of the soil. The screwdriver will easily penetrate to the soil depth which has
received sufficient water. The screwdriver test can also be used to help determine
where and when there is a need for irrigation.
Conserve water by knowing when to water
- The best time to water a lawn is from 6 to 8 a.m. During this time the water
pressure is highest, disruption of the water pattern from wind is low, and
water lost to the atmosphere by evaporation is negligible. Watering early in
the morning also has the advantage of reducing the chance of turf diseases
that require extended periods of leaf moisture. Avoid irrigation during mid-day
and windy conditions.
- Move sprinklers frequently enough to avoid puddles and runoff. Difficult-to-wet
areas such as slopes, thatched turf and hard soils may benefit from application
of a wetting agent to improve surface penetration of water.
- Water only when the plant tells you to. Become familiar with areas of the
lawn that wilt first (blue/purple leaves, rolled leaves, foot printing). Water
within a day of observing these symptoms.
- Water problem areas by hand to postpone the need for irrigation of the entire
lawn. Some areas of a lawn usually wilt before others. These areas, or "hot
spots," may be caused by hard soils that take up water slowly, slopes, southern
exposures and warmer areas next to drives and walks. Lawns that have unusual
shapes also may require some hand watering to avoid unnecessary watering of
paved surfaces, mulched beds and buildings. Soaker hoses that have a narrow
pattern and supply water at a slow rate may be useful in these areas.
Watering new lawns
Newly seeded or sodded lawns require special irrigation. A newly seeded lawn
should be watered daily and may need as many as four light waterings in a single
day. Keep the seedbed moist, but not saturated, to a depth of 1 to 2 inches until
germination occurs (green cast to lawn and seedlings are 1/4- to 1/2-inch tall).
Seedlings of a new lawn must not be stressed to the point of wilt. Continue
with light applications of water -- 1/8 to 1/4 inch -- one to four times
a day.
Apply straw (one bail per 1,000 square feet) at time of seeding to help shade
the ground and prevent rapid drying of the soil surface. Straw also will reduce
seedling damage from the force of large sprinkler drops. Watering with a light
mist is best for establishing new lawns. As seedlings reach 2 inches in height,
gradually reduce the frequency of watering and water more deeply. After the
new lawn has been mowed two or three times, deep, infrequent waterings are the
best.
Newly sodded lawns require watering one or two times a day. Begin irrigation
immediately after laying sod. Plan your sodding operation so that a section
of laid sod can be watered immediately, while other areas are being sodded.
Sod should be watered so that the sod strip is wet as well as the top inch
of soil below the sod. The first irrigation will take about an inch of water
to achieve complete wetting of the sod. After watering, lift up pieces of sod
at several locations to determine if it has been adequately irrigated. Continue
watering one to two times a day with light irrigations to prevent wilting and
to ensure a moist soil just below the sod layer.
As sod becomes established and roots penetrate and grow in the soil, gradually
reduce the frequency of watering but wet the soil deeper. After sod has been
mowed two or three times, deep, infrequent watering should be practiced. During
hot, windy conditions, establishing sod may require several light mistings per
day to prevent wilt and potentially high lethal temperatures. In this case,
light misting, just to wet the leaf surface and not to supply water to the soil,
cools the grass plant as water is evaporated from the leaves.
Do not over-irrigate (saturate) the soil because that will inhibit sod roots
from growing into the soil. If the sod cannot be watered on a daily basis, thoroughly
water the sod and soil to a depth of 6 inches. This will delay the rooting time
of sod but will reduce the chance of rapid drying and severe loss of grass.
Summary
Good lawn care practices save water and harden turf in preparation for dry periods
or local lawn watering restrictions. Taller mowing and fall nitrogen fertilization
develop a hardy and efficient root system that reduces the need for supplemental
irrigation.
Irrigation schedules should be kept flexible and associated with identification
of lawn wilting. Choose a sprinkler that best fits your lawn size and shape.
The amount of water a sprinkler applies should be determined to accurately water
lawns. Newly seeded or sodded lawns require daily irrigation during establishment.
Figure 1
Some sprinkler types and their applications
| Sprinkler types |
Comments |
Rotary or impulse |
Rotary head shoots water out in a pulsating action. Some have adjustable
screw or paddle that breaks up jet stream and disperses water pattern. Can
be set to water partial circles. Best for large areas. Accurately distributes
water when placed in an overlapping triangular pattern. |
Traveling |
Path guided by hose placement. Traveling action covers a large area without
assistance. Requires level ground and overlapping pattern to evenly distribute
water. Used primarily on large lawns. Can easily be manipulated for large
irregular lawn shapes. Wheel drive types are not suitable for newly seeded
lawns where soft soil conditions result in stuck sprinklers. |
Whirling-head |
Deposits largest amount of water closest to spray head. Use a 50 percent
overlapping pattern. Deposits larger amount of water in short period of time
and requires frequent movement. Good for watering tight locations. |
Stationary |
Water applied in irregular pattern even with overlapping moves. Difficult
to water large areas uniformly. Good for spot-watering tight locations. Deposits
a large amount of water in a short period of time and requires frequent movement. |
Oscillating |
Delivers water in a rectangular pattern. Deposits most of the water near
sprinkler head. Difficult to achieve even water pattern on large areas that
require sprinkler relocation. Can be adjusted to water smaller rectangular
areas and other tight locations. |
Soaker-hose |
Flat pin-holed hose sprays fine streams of water. Requires several moves
to water medium-sized lawn. Delivers water slowly -- good for hard-to-wet
locations. Can be manipulated to water irregular areas and long tight areas
along house or walks. |
Figure 2
Proper sprinkler pattern overlap of 50 percent
G6720, reviewed March 2004