To water or not to water the lawn: that is my question.

As we enter the third week of summer, gardeners are faced with that age-old question:  To water or not to water the lawn. (1) water the grass to keep it green or (2) don’t water and watch the lawn turn brown and dormant.

If you chose is not to water your lawn, 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.  Tall fescue is an exception because it has no means of escape.  Three weeks or more without rain in the summer can injure or kill tall fescue.  Nevertheless, any bare areas that arise can be easily repaired in the fall with seed or sod.

If you choose to irrigate your lawn, it’s important that you water efficiently:  water the lawn when it exhibits drought stress symptoms; apply an appropriate amount of water; and water at the right time of day.

A “thirsty” or drought-stressed lawn develops a bluish-gray cast that turns back to green when the lawn is watered; footprints stay in the grass after you walk over it; and leaves become wilted and rolled.

To prevent the lawn from going dormant, 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 of water, I highly recommend that you calibrate your watering system by following these simple steps:

  1. Place several equally-sized coffee cans or other straight-sided, flat-bottomed containers randomly throughout the area to be irrigated.  For above-ground, portable, hose-end sprinklers,  arrange containers in a straight line away from the sprinklers to the edge of the water pattern.
  2. Turn the irrigation on for 15 minutes.
  3. Turn the water off, collect the cans and pour all of the water into one of the cans used.
  4. Measure the depth of water you collected.
  5. Calculate the average depth of water by dividing the total amount of water in inches by the number of cans. For instance, if the total depth was three inches, and you used six containers, then the average depth would be 3/6, or 0.5 inches.
  6. Multiply the average depth by four to determine the application rate in inches per hour. For example, one-half inch multiplied by four equals two inches per hour.  If you run the system for one hour, it will apply two inches of water; run it for half an hour, and it will apply one inch.  If, during irrigation, water runs off the lawn, apply a half-inch, stop the system and let it soak in, then apply more.

Water late at night or early in the morning when dew has already formed.  It will not encourage disease outbreaks and 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.

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.

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