When should irrigation systems be blown out? When blowout should occur depends on the region in which you live. Some regions begin blowout as early as August, and it can continue through early December, since ground temperatures cool slower than air temperatures.
When the air temperature dips below freezing, the water trapped in the system will freeze. Seriously damage could occur to your entire irrigation system. By turning it off just before the cold weather arrives, you can ensure that your lawn will receive the water it needs to thrive.
Like anything else that contains water, fire sprinkler systems are subject to freezing at 32 degrees Fahrenheit. Luckily measures such as heat tracing and antifreeze exist to prevent this.
Depending on where you live, early to late fall may be the best time to winterize your sprinkler system. If you're not sure when is a good time to do it, try to schedule your winterization plans around the first week before your first winter freeze.
As mentioned earlier, the arrival of freezing temperatures varies from region to region. Generally speaking, those in northern areas should consider shutting down their irrigation systems as early as October, while those further south can usually wait until November or December.
Generally, a good benchmark is when temperatures drop below 50°F, which is usually in October for places with cold winters. “You should stop watering your lawn when temperatures consistently drop below 50°F during the day,” says Zahid Adnan, founder of the Plant Bible.
Without proper preparation, your sprinkler system might be damaged by freezing temperatures. Shut off the water supply to the irrigation system. If you have a timer/automatic controller, don't forget to turn that off too. Drain water from the pipes, sprinklers, and hoses.
The best suggestion for when to turn off your sprinklers is right when the cold weather begins. Keep an eye on your local forecast for when the big freeze is coming, and plan around that. Give yourself a few days as a cushion just to be safe, and begin preparations for the winterization process.
Generally, most lawns need about 1 inch of water per week, including rainfall. This typically means running your irrigation system for about 1–2 hours per week, depending on its type and delivery rate.
Although the point of any water freeze is 32 degrees Fahrenheit, which does put your sprinklers at risk, it takes a sustained hard freeze to truly affect your sprinkler system. A hard freeze is considered around 28 degrees Fahrenheit.
At the freezing point of 32 degrees, Fahrenheit water left in your sprinkler system can expand and burst the pipes.
Prevent Frozen Pipes
Set home thermostats above 55 degrees during cold weather. Drip cold water in farthest faucet from your main valve. Moving water keeps pipes from freezing.
Insulate your assets:
Shut off the water supply to the irrigation system. The main shut off valve for your irrigation system needs to be protected against freezing. Make sure it is wrapped with insulation (foam insulation tape and a plastic bag) to protect it from harsh winter temperatures and prevent it from freezing.
In the late spring, rotor irrigation zones typically need to run 30-45 minutes per zone, and spray irrigation zones typically need to run 8-12 minutes. We recommend watering 2-3 days a week during late spring. In mid to late summer with extreme heat, your lawn will need more water.
Aim to prepare your irrigation for winter about the time autumn leaves start falling. There are three common ways to drain sprinkler systems before winter: manual drain, automatic drain or blow-out. Manually Draining a Sprinkler System. Open every manual valve, including any near the manifold.
The best time to water grass is early in the morning, between 6 a.m. and 10 a.m., as the cooler air and calmer breezes allow water droplets to reach the grass roots before evaporating. Watering during this period helps in preventing wasteful evaporation and the risk of lawn diseases associated with nighttime watering.
The answer is “before temperatures generally dip below freezing at night.”
For example, rotor sprinkler heads might require 20 to 30 minutes of straight watering time, while a traditional spray head zone will only need 5 to 10 minutes.
9NEWS spoke with garden experts who say October is the perfect time to winterize sprinkler systems, especially once lows begin to drop below freezing at night and lawns require less water with daytime highs in the 60s.
Lawn Watering Practices
Frequent watering encourages shallow root growth and unhealthy grass. Deep, less frequent watering encourages grass roots to grow deeper into the soil reservoir from which to draw moisture. Deep roots also mean the lawn will be less affected by surface drying.
Freezing temperatures are the primary concern for sprinkler systems, as water inside the pipes and sprinkler heads can freeze when temperatures in your region begin to dip below 32°F. This freezing causes water to expand, which may result in cracked pipes and damage to components like valves and fittings.
When the weather is very cold outside, let the cold water drip from the faucet served by exposed pipes. Running water through the pipe - even at a trickle - helps prevent pipes from freezing.
NOAA's National Weather Service - Glossary. A freeze is when the surface air temperature is expected to be 32°F or below over a widespread area for a climatologically significant period of time. Use of the term is usually restricted to advective situations or to occasions when wind or other conditions prevent frost.