In spring, let Mother Nature water the lawn

Yes, your grass is turning green. No, you shouldn’t turn on your irrigation system. Here’s why.

April 1, 2019 | By: Kim Unger

Welcome to the roller coaster of spring weather in the Mile High City. At any given time, it can snow, hail, rain or be unseasonably hot. But just because the spring season has officially sprung doesn’t mean it’s time to kick on your irrigation system.

a bush weighed down be heavy, wet snowfall, with a sled, ski and snowboard next to it
This week has seen warm, sunny days but parts of Colorado could experience blizzard conditions on Friday.


That grass in your yard has a secret buried deep in its soil: winter moisture. With short daylight hours, cool nights and the sun traveling lower across the sky, the water in the soil evaporates more slowly than it does in the summer. So while your grass lies dormant, it still has moisture sustaining its root system.

It may be tempting to start up the irrigation system when the grass begins to turn green, but our experts advise holding off just a bit longer because the potential for winter weather lingers.

“We can have deep freezes in April,” said Jeff Tejral, Denver Water’s efficiency manager. “Deep freezes will damage an irrigation system that was not properly winterized.”

Waiting until after the last freeze — typically around May 5 — to turn on your system.

While leaks or breaks can occur on exposed pipes and backflow devices above ground, damage can occur underground, as well. When temperatures drop below 30 degrees, water sitting in the pipes can freeze and expand, cracking the pipe. This damage may not be discovered until abnormally high water bills show potential leaks in the system.

Irrigation system leaks can lose as many as 10,000 gallons per month per zone. Aside from the higher bills and wasted water, repair costs can also put a dent in your household budget.

You can avoid this by simply rolling out the garden hose and hand-water trees, perennials and late-fall plantings during warm, dry periods. If your lawn has brown spots, use water efficiently by hydrating the distressed areas instead of the entire lawn. Just don’t forget to disconnect the hose from the spigot in case freezing weather moves in.

If you are concerned about your soil’s moisture, check it by inserting a screwdriver into the ground; if it goes in easily, it’s got enough water. You can also aerate your lawn to help water absorb rain or snowmelt to provide added moisture without watering.

And what should you do if you turned on your irrigation system in March? Winterize and shut off your system until after the last freeze to protect it from potential damage.

gif explaining why you should not turn on your irrigation system in the early spring

7 thoughts on “In spring, let Mother Nature water the lawn”

  1. Hi Kim
    Are a native to Colorado or a translation I always turn on my sprinkler on in mid April a lot of my lawn customers never had on freeze yet 20 years just wrapped up the back flow your fine all so as dry it has been in February and March the grass more important the trees and bushes nerd them more I just the water board was better informed about these things

    1. In Castle Rock we have seen problems with our customers lines (above ground) as late as April, it just takes one night of below freezing temperatures to crack the pop it and bonnet. We always tell our clients to turn on their system around mothers day, its the easiest to remember. Also by waiting to turn on your system it trains the roots of turf grasses to look deeper for water, making the landscape more drought tolerant. Happy spring!
      Chris Paulo

      1. Thanks for reading Chris, you’re spot on with the importance of root depth. It’s why we recommend that customers cycle and soak their lawn to allow water to travel further into the soil, down to the roots. It not only creates healthier turf, but also prevents runoff of water onto sidewalks. Happy spring to you as well, and thank you for commenting!

  2. When does Denver water recommend to water? May. When does Denver start regulating water use and handing out fines? May. I will turn on my sprinklers and water the crap out of my lawn until may

    1. We understand customers have different preferences and will water when and as they see fit. We aim to provide information and tips to help customers water as efficiently as possible, as we believe wasting water is never OK.

      The point of this story was to highlight tips specific to this time of year, in that we recommend checking the soil moisture to determine if your landscape needs some additional TLC during the winter and early spring months. Because Denver still experiences freezes in April, we suggest hand-watering during this time so sprinkler systems don’t break during a late-season cold-spell – which can result in a high water bill. Summer watering rules run from May 1 to Oct. 1, and act as a guide to ensure you’re taking adequate care of your landscape without wasting water. Our story, “To water, or not to water, that is the question,” offers more guidance related to watering.

  3. We never turn on our sprinklers until late May because we know that soil temperature – not water – is vital for turning lawns green. Turning on sprinklers too early may cause you to “feel good” but, in reality, the grass doesn’t need the extra water. Grass roots will dig into the soil deeper and result in a healthier blade of grass for the entire season if you don’t spoil things by turning on the sprinklers too soon. (It also helps save on your water bill… hence, a “win, win” situation.

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