One simple fact, that water expands when it freezes, is responsible for a lot of spring headaches for those with sprinkler systems. Depending on how much water is in your sprinkler pipes at the exact moment it freezes, it could burst through your line, break your sprinkler heads, and cost you thousands in repairs. That’s why it’s best to empty your sprinklers before a freeze and turn them off as part of your winterizing routine.
However, turning off your sprinklers too soon may dry out your lawn, affecting its health at a very critical time. If your grass suffers late fall, it will have trouble rebounding in the spring. Therefore, you need to winterize your sprinkler system about a week before the first freeze. That week won’t harm the grass and will give you enough time to get the job done if the frost comes a bit early.
Check your Frost Date
Organizations like the Old Farmer’s Almanac predict when the first frost will occur in your area every year. It’s intended to help gardeners plan when to bring in frost sensitive plants, but you can also use to help predict when you should winterize your sprinklers.
When should you turn off your sprinklers in Denver? The Almanac predicts that the first frost will occur on October 5th, which has already passed! So, you should winterize your sprinklers as soon as possible this year.
Frost dates aren’t perfect. Instead, there’s a thirty percent chance that the first frost will happen before the frost date, in this case, October 5th. So don’t rely on the date exactly. Mark your frost date in your calendar and pay attention to the more specific weather conditions that week, or month, to know exactly when you should winterize your sprinkler system.
When a Freeze is Coming
Should you run your sprinklers before a freeze? If there is enough time for the water to absorb into the ground, then yes, you should. The water will help insulate the roots. However, if the water will freeze on the grass before it absorbs into the ground, it could do significant damage to the grass. Any plant may die over the winter if it remains encased in ice.
On the other hand, if you’re expecting a nighttime freeze, you should blow-out your sprinkler system. Yes, you may get some water on the grass, which may kill it. However, replacing the grass is much easier and less expensive than replacing a burst sprinkler system.
You also won’t get as much water on the grass during a blow-out as you will during a regular watering, because only the water already in the pipes will be delivered. Your chances of harming the grass are low, and the risks of not blowing out a system before a freeze is high.
While you’re getting your sprinklers winterized this year, don’t forget to mark your calendar for next year. The average frost date for Denver is October 5th, but the Farmer’s Almanac will have a more specific date in their 2019-2020 almanac.