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Irrigation Winterization

November 12, 2009


If you haven’t already done so, the ritual of irrigation blow out is certainly on everyone’s mind this time of year. This procedure signifies the end of another growing season along with the realization that winter and the accompanying freezing temperatures are probably right around the corner. Properly blowing out an irrigation system ensures that minimal damage will occur during the winter months. Although blow out is a yearly occurrence, there doesn’t seem to be a great deal of literature available about this important procedure. There seems to be various philosophies and most learn from field experience.

One aspect of blow out that has changed over the years is the pressure which the system is blown out. One reason for this change is the fact that sprinkler heads are now primarily comprised of plastic componts compared to their steel predecesors. As a result, the pressure which the system is blown out has been reduced. One way to help reduce the pressure is by using a pressure regulator.

The pressure regulator is usually mounted just off the compressor. The pressure can be monitored and adjusted by a handle on top of the regulator. I have often heard that 50 psi is sufficient to blow out most systems. Obviously, the higher the pressure, the greater the chance of causing damage to the piping system and the sprinkler heads. The other consequence of using higher pressures is coupled to the pressure of the compressor.

Compressors also have a pressure gauge and increasing the pressure of the regulator will decrease the pressure inside the compressor and vice verca. Most compressors should not be operated under 80 psi. Under 80 psi, oil can blow past the seals in the compressor and enter the piping system. Of course you won’t realize this has happened until you charge the system in the spring and oil comes spewing out of sprinkler heads.

Let me know if you have any tips from the field concerning winterization of irrigation systems. Hope everyone has a safe and successful blowout.

Marcus Jones

Graduate Research Assistant


It’s Beginning to Look a Lot Like Christmas

November 13, 2011

Many parts of the state received their first snowfall last week. The days are shorter and 4” soil temperatures are slipping from the low 40’s into the high 30’s. Most trees have lost the majority of their leaves. Long-establishing creeping bentgrass greens display a spectrum of purple patches. Everywhere you look, there are signs that another growing season is coming to an end. But irrigation winterization may best signify that the growing season is over and winter is just around the corner.

Irrigation winterization is the process of evacuating water from the irrigation pipes to avoid damage from freezing temperatures. While a portion of the water can be evacuated at dead ends and low points of the piping through manual and automatic drain valves, larger irrigation systems also “blowout” the piping system using compressed air. This method of winterization can be very damaging to the piping system and dangerous to workers if proper safety procedures are not followed.

I was reminded of the hazards that can occur during the winterization procedure when I received the picture below from a former student. In this scenario an individual head would not activate from the satellite box and the employee went to flag on the head. When the head activated, the internal assembly broke free from the bucket striking the worker under the chin.

Irrigation winterization can be dangerous and safety precautions need to be taken to avoid injury.

This post will outline some of the basic safety measures that should be followed to avoid personal injury and undue stress on the irrigation system.

Use a safety harness to tether the air hose to the compressor. Air hoses connect to the compressor though a claw or similar type coupling. The connection is usually secured with cotter pins or wire but also consider using a safety harness. The harness will prevent the hose from flailing about in the event the connection fails while under pressure.


A harness that connects the air hose to the compressor provides additional safety in case the connection fails when under pressure.

Do not force air through the backflow preventer. Be sure to hookup after the backflow preventer as forcing air through this component can cause damage. First, blowout the system, then allow the backflow preventer to drain.

Regulate the air pressure with a pressure regulator. Even though larger irrigation system may operate with water pressures in excess of 100 psi, air pressures of this magnitude can damage the system. Use of a pressure regulating valve can help prevent over-pressurization. Most manufacturers recommend air pressures around 50 psi.

A pressure regulator can help prevent excessively high pressures from damaging valves, pipes, and irrigation heads.

Do not stand directly over irrigation components when under pressure. Air is less viscous compared to water and can generate greater stress under comparable pressures. Weak points in the irrigation system can fail under air pressure. Protect yourself from personal injury by staying clear of irrigation components when under pressure. It’s also a good idea to wear proper eye and ear protection during the winterization process.

Do not work on a sprinkler head while under pressure. If a head sticks on or won’t activate automatically or manually valve the section off and bleed the pressure through a quick coupler. Once the air stops at the quick coupler the head is safe to work on.

Evacuate water ahead of time. Before activating individual sprinkler heads use drain valves and quick couplers to initially evacuate water. This will reduce the amount of water in the system and can shorten the time needed to evacuate air through sprinkler heads. Less air moving through valves and sprinkler components and will help cut down on wear and tear.

Quick couplers and manual drain valves can be used to drain water before evacuating water through sprinkler heads.

Do not allow sprinkler heads to run for prolonged periods of time. Sprinkler drive mechanisms are normally lubricated as the water moves through the internal assembly. In the absence of water, heat caused from friction can damage these plastic components. Cycle between one or more stations to avoid excess buildup of heat.

Taking care to follow these safety procedures can help the winterization process go smoothly while minimizing damage to the irrigation system and preventing personal injury.

Hoping you have successful (and safe) winterizations!

Marcus Jones
Assistant Scientist




Why Was Winter 2013-14 So Hard On Our Landscape Plants?

May 16, 2014

I think we’d all agree, the past winter season was a long and difficult one.  Even now, in the third week of May, temperatures are struggling to reach 70°.  And the three overriding questions remain…will summer ever arrive?  How do I explain to my boss, club members, clients, etc. why so many plants look dead after the winter of 2013-14?  And perhaps most importantly, why was this past winter so tough on landscape plants? 

Consider these events important events:

  • As we entered late fall and early winter, soil conditions were very dry.
  • As a result, many landscape plants entered winter under stress or in a weakened condition.
  • Severe low temperatures (before measureable snowfall) caused the soil to freeze to impressive depths.  This could have resulted in root death to sensitive or stressed plants.
  • When snowfall eventually arrived, it blanketed the ground without interruption, persisting until early spring in some locations and ensuring frozen soil until late March/early April.
  • Strong winds seemed to be an everyday occurrence.  When coupled with high light intensity and frozen soil conditions, the damage to evergreens became a foregone conclusion.
  • Finally, low temperatures, the likes we haven’t seen for many years, helped create the perfect storm.

Mitigating Winter Injury

Winter injury may not be immediately apparent when plants resume growth in the spring. Some plants may actually leaf out and appear quite normal for a time, only to decline and die later during stressful summer conditions.  To minimize unsightliness and promote plant health, dead wood should be pruned out as it becomes apparent. 

Providing appropriate amounts of water to compromised plants may be the most important task for landscape managers.  Plants already suffering from winter injury may die quickly if forced to cope with drought stress.  Mulching the area around trees and shrubs with organic materials like wood chips or shredded bark will help conserve soil moisture and keep lawn maintenance equipment away from sensitive bark and stem tissue. 

Finally, it is important to remember that fertilizer is not a cure-all for winter-injured plants.  If a soil test determines that mineral elements are deficient, then applying an appropriate fertilizer makes perfect sense.  But high rates of fertilizer will not miraculously close sunscald wounds, restore life to killed roots or buds, or reverse any of the other negative effects resulting from the memorable winter of 2013-14.

Jeff Iles

Department of Horticulture

Iowa State University

Below you will fine a few pictures taken by Dr. Iles around Ames. 



Putting the Field to Bed

To insure health in the spring, an athletic field must be properly cared for before winter hits. This publication discusses how to get a fall sport field ready for the winter and how to get a spring sport field ready for competition.



May 3, 2013

We received several more inches of snow overnight in Ames.  The heaviest snow I heard of was in Britt, in North Central Iowa, where they had 11 inches.  That was a new record for May.

The first picture is from Teresa Balsley at Veenker Golf course on ISU campus.

Veenker Golf Course Winter

I took the next two pictures this morning on Indian Creek golf course behind my house in Nevada, Iowa.  The first one is the fourth tee and the second one is of the 3rd green.

Indian Creek Golf Course Winter

Indian Creek Golf Course Winter

I took this one from facebook.  It shows one of the guys at Coldwater Creek golf course in Ames who didn't let the snow stop his golf game.

Here is something I want you golf people to watch for.  The first picture is of the sclerotia (resting bodies) of Typhula incarnata, the fungi that causes Gray Snow Mold.

Gray Snow Mold

 The second one is a commercial shot of germinating sclerotia.  This is a very rare site.  I have only seen it once in Iowa.  It can occur right after a very early or very late snow on actively growing bentgrass greens.  They can also be dark colored and take on a 'fiddle head' appearance, like a fiddle head fern.  If anyone sees this as the snow melts, snap some pictures for me.

Here are two additional pictures that I just received from Derek Richards, assistant at Veenker golf course,  while I was posting this blog.  It shows the 18th hole on Veenker on April 24 and then again this morning, May 3.


More winter survival information from Chicago.

April 23, 2010

Here is another post from the Chicago area on winter damage. This one is from Ben McGargill at Wynstone Golf Club. He posted last week on the effect of covers under ice on Poa survival.


At Wynstone, our greens are primarily Poa annua. Some are 50/50 bent/poa while several are 90% - 95% poa. The club had purchased tarps for all 18 greens in the fall of 2009, and we spent the first two days of December tarping all of the greens on the golf course.

Since December 1st was my first day at Wynstone, I was only able to see the greens as we tarped prior to snowfall on the 3rd. When deciding which greens to clear of snow and ice, I relied heavily on recollection of ice damage in the past.

Most of the greens were covered in ice following a 1.5 inches of rain followed by a hard freeze at the end of December, but in January we received two days in the forties. Several days before the warm temperatures were predicted, we began snow blowing our problem greens in hopes that the ice would melt, and it seems to have been successful. Our only problem was on #17 Green, which we did not clear, and all of the death occurred where the tarp failed to cover the edge of the green (see last week’s post).

The picture below is of a low spot on the front of #11 green, which has been one of the most problematic areas. This is an area we monitored and removed ice in January. As you can imagine, we were happy to see green turf.

Ben McGargill
Wynstone Golf Club
Barrington, Ill.