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Now is not the time to shut off your irrigation systems

Posted 10/8/2009

Though it may seem logical to stop watering after the first freeze, Extension Educator Joanne Skelly of University of Nevada Cooperative Extension said this practice can damage your plants. Even though the temperature has dropped, the humidity level in October is still extremely low. Weather patterns in the fall vary from occasional night freezes to balmy days in the 60’s and 70’s.

Skelly said cutting off water abruptly could damage trees, flowers and lawns.

"The weather was still hot last week, so plants were using quite a bit of water," Skelly said. "To suddenly stop watering will stress them. A better technique is to harden off trees."

By "hardening off" trees—reducing the amount of water provided and lengthening time between watering—you can prepare them for winter when irrigation systems should be shut off to prevent damage to pipes.

Precipitation in October rarely soaks the ground, and plants need a deep soaking, Skelly said.

To "deep soak," water to a depth of about 18 inches. With trees, water out to the drip line (the outer reach of the branches) all the way around the tree.

"Do this slowly so that water does not run off," Skelly said. "Flowers have a shallower root system, so they do not need as deep a soaking."

Lawns require approximately one inch of water per week right now, according to the Western Regional Climate Center at the Desert Research Institute in Reno. New plants will need water more often.

Skelly said to keep an eye on the forecast to determine the best time to shut off irrigation systems.

"You should shut off your system before there is a freeze cold enough to damage your pipes," Skelly said. "That time is usually around early to mid-November, but sometimes we have warm spells. If it warms up during the day, it’s not so bad."

Most importantly, Skelly said, gardeners should never stop watering their plants.

"Plants do need water through the winter," Skelly said. "It may be that you have to turn the irrigation system back on and empty it or haul hoses around, but you can’t rely on precipitation. You should water about once per month during the fall and winter."

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