Water Deep, Not Daily: An Inch a Week and the Tuna-Can Test

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We see two kinds of watering problems on our routes. Some lawns get too little and go brown in the first hot week of July. Many more get a short sprinkle every evening, which looks like care but trains the grass to keep its roots near the surface, where they dry out first.

The fix for both is the same: water deeply and less often.

How much water a lawn actually needs

Cool-season lawns in the Linden Valley need about 1 inch of water per week in summer, and up to 1.5 inches during a heat wave. That total includes rain. A good thunderstorm can drop an inch in an hour, so check before you water.

Split that inch into two or three sessions a week instead of seven short ones. Each soaking should wet the soil 4 to 6 inches down. Roots follow water, so when the moisture is deep, the roots go deep too, and the lawn can ride out a dry spell without wilting.

The tuna-can test

Most people have no idea how much water their sprinkler puts down. Neither did we until we started measuring. Here's the test we use on new irrigation accounts, and it costs nothing:

1. Collect five or six straight-sided cans — tuna or cat-food cans are perfect. Any shallow container with straight sides works.
2. Set them around one sprinkler zone, some near the heads and some out in the middle.
3. Run that zone for 15 minutes.
4. Measure the water in each can with a ruler and average the results.
5. Multiply to find how long it takes to reach half an inch, and how long to reach an inch.

If the cans average a quarter inch in 15 minutes, that zone needs 30 minutes to put down half an inch, and two of those sessions a week covers it. If one can is nearly dry while the others are full, you've also found a clogged or misaligned head.

Run the test for each zone. Spray heads, rotors and drip lines put out very different amounts, and a timer set to the same minutes on every zone almost never waters evenly.

Water early in the morning

The best time to water is between about 4 and 9 am. The air is cool and still, so less water evaporates or blows away, and the grass dries off quickly once the sun comes up.

Evening watering leaves the lawn wet all night, which is exactly what brown patch and other fungal diseases need. Midday watering isn't harmful to the grass, despite the old myth, but you lose a lot of it to evaporation.

Signs your lawn is thirsty

You don't need a moisture meter. Look for:

• Footprints that stay. Walk across the lawn. If your footprints are still visible a half hour later, the blades don't have enough water to spring back.
• A blue-gray tint. Drought-stressed grass turns a dull, bluish color before it turns brown.
• Folded blades. Many grasses roll or fold their blades to save water.
• The screwdriver test. Push a long screwdriver into the soil. If it slides in 6 inches easily, there's moisture down there. If it stops at 2 inches, it's time to water.

Dormant is not dead

Cool-season grass can go dormant in a long dry spell. It turns tan, stops growing and waits for rain. A healthy lawn can stay dormant for three to four weeks and green back up when water returns.

If you decide to let your lawn go dormant, keep it alive with about half an inch of water every two weeks, keep foot traffic off it, and don't fertilize until it greens up. What you shouldn't do is water just enough to wake it up and then stop; going in and out of dormancy is harder on the grass than staying dormant.

During drought watering restrictions, our Weekly Care customers can skip mowing weeks at no charge. Dormant grass doesn't need cutting, and mowing it only stresses it further.

A few irrigation habits we recommend

• Use the cycle-and-soak setting if your controller has one. Clay soil can only absorb so much at a time. Running a zone twice for 15 minutes with an hour between beats one 30-minute run that mostly runs into the street.
• Add a rain sensor. They're inexpensive and stop the system from running in a storm.
• Adjust by season. Your lawn needs much less water in May and September than in July. Most controllers have a seasonal adjustment percentage; use it.
• Check heads monthly. Mowers, cars and kids knock heads out of line. A head spraying the sidewalk is wasting water and leaving a dry strip of lawn.

When to call us

If one area browns while the rest of the lawn stays green, it's usually a coverage problem, not a watering-schedule problem. Our irrigation checks look at every zone, adjust or replace heads, and set your controller to what your yard actually needs. You can add one to any plan, or ask about it on a free estimate.