Gardening: Smart watering can help keep lawn healthy

The Master Gardener Plant Clinic has been busy answering questions about lawns during this summer of early and lasting heat.

Lawns are taking a beating and the assault won’t end until it cools down in the fall.

Our dry lawn issues started long before we started gardening this year. The winter and spring months saw below-average rain and snowfall. As a result, we went into May with dry soil.

We had an unusual early heat wave in May, which added to the dry soil issue. By the time we realized we needed to turn on the sprinklers, the grass was already getting stressed.

Because everything was green with spring growth, we didn’t realize how dry things were. Now after a monthlong heat wave, our lawns are really struggling.

When it gets hot in late July and August, lawns tend to go dormant anyway until it cools down in September. They will look terrible until then, but they will survive. We need to continue watering them to keep the roots alive. Bluegrass lawns tend to look the worst in the heat while fescue lawns are more drought tolerant.

There is no way to set a standard amount of time a sprinkler system needs to run to provide enough water.

It depends on your soil type. If you have sandy soil, you will have to apply more water than you would if you had loamy soil.

Then there are the new guidelines put in place in the city of Spokane and other places that limit the days you can water and for how long. These guidelines are the future of water use even in a region with a strong Spokane Valley aquifer. Times are changing, and the role of the lawn will be changing.

In general, water lawns only two to three days a week for enough time to get water 3 to 4 inches into the soil. That might mean watering for between 30 and 45 minutes at a station. Bluegrass needs about 1½ inches of water. Set out flat tuna cans when your system is on and measure how much water the system puts out and use that to calculate your run times. Water during the early morning, evening and overnight rather than the heat of the day. If you water during the heat of the day, most of that water will evaporate.

This time of year, mow lawns to a height of 2 to 3 inches. The grass blends provide shade for the soil and cut down on evaporation. Golf course short grass is not healthy for lawns.

There is no point in fertilizing lawns this time of year because the grass can’t use it in the heat. Wait until mid-September after the grass has perked up.

Nor is it a good time to apply weed controls. Weeds are also dormant and the chemicals can evaporate into the air and drift onto other desirable plants, causing damage and even death.