Watering the Lawn
As the spring dry spell tightens its grip on our lawns and landscapes,
gardeners are faced with that age-old question: To water or not
to water the lawn this summer.
If your choice is not to water your lawn and let it turn brown,
don't let the dead brown leaves frighten you. The lawn grasses
have gone dormant. Grass plants possess buds in their crowns and
rhizomes (underground stems) that may remain alive and grow when more
favorable conditions return.
Since all grasses are not created equal, expect warm-season bermudagrass
or centipedegrass lawns to tolerate hot dry spells better than cool-season
tall fescue lawns. However, any bare areas that arise can be easily
repaired with seed, sprigs, or plugs. If you choose to irrigate
to keep the lawn green, water efficiently--only when the lawn really
needs it.
The following techniques will help you identify signs of "thirst" or drought
stress:
- COLOR TEST: When water becomes unavailable for an
extended period, a lawn will exhibit a bluish-gray cast.
- FOOTPRINTING: Walk across your lawn and examine the
lawn behind you to see if your steps left any "footprints." Your footprints
will appear in a lawn when the grass plants have low levels of water in their
tissues. When the grass blades are compressed by your feet, the low water
levels prevent the grass blades from springing back up. If your footprints
remain for an extended period of time, the lawn should be watered to prevent
the grass from turning brown and becoming dormant.
- LEAF CHECK: During dry periods, grass leaves respond
by wilting, rolling, or folding; use these symptoms as a signal that watering
is necessary to prevent the turfgrass from becoming dormant.
- SCREWDRIVER TEST: Press a screwdriver (or a reasonable
facsimile) into the lawn. If the soil is very dry, it will be difficult to
push the screwdriver into the ground.
If your lawn exhibits symptoms of drought stress, apply about one-inch
of water to your lawn; this amount wets most clay soils to a depth of
6 to 8 inches. If all of this amount cannot be applied at once
because water runs off the lawn or puddles up, then apply one-half inch
at a time. Allow the water to soak in before continuing. If
you have a portable sprinkler move it frequently to avoid runoff-unless
you don't mind watering your neighbor's lawn. To apply the right
amount, use your screwdriver to determine the depth of water penetration
2 to 4 hours after watering. It'll be easier to push into moist
soil and harder in dry soil.
Water late at night or early in the morning when dew has formed. Watering
a lawn already moistened by dew will not encourage disease outbreaks.
Besides, it will save you money. For example, at midday,
in hot, dry and windy weather, 30 percent or more of the water evaporates.
Watering at night cuts evaporation in half, to 15 to 20 percent.
Since it takes 640 gallons of water to irrigate 1,000 square feet
with one inch of water, late night watering gives substantial savings
in cost and in the amount of water you apply.
Once you water, do not water again until you see signs of drought stress. Never
water the grass every day except during establishment. Watering
every day with a small amount will encourage a shallow root system, making
the grass less drought-tolerant.
Watering the lawn in the summer will keep it green, but it also has some
consequences. Besides having to mow that lush new growth on a
regular basis, watering may encourage weed growth, stimulate disease
outbreaks, and raise your water bill.
So, however you answer the question this summer--to water or not to water
the lawn --stick with it. Flip-flopping between the two can weaken
and injure your lawn.
--Bob Polomski, Extension Consumer Horticulturist--Clemson University
