How long should I run my irrigation system?

Common Irrigation Question #2 – How long should I run my irrigation system?

The question of how long to run an irrigation system to get the best results is something I hear often when speaking to customers that have moved into a home with irrigation or have just installed a new system.  The answer to this will depend on a number of variables that the customer will face on the property that is irrigated.  First thing is the common belief that one inch of precipitation a week is needed to maintain your turf and/or plants.  While this is a good starting point there are a number of variables that come into play that can alter this baseline in either direction.  Most customers set the program on the irrigation controller in the spring and leave it alone only to check it when they see the landscape dry or so wet that it’s causing problems.


The base line thinking in the industry has always been 25 – 30 minutes for turf rotors and 15 – 20 minutes for spray heads every other day watering in turf applications. While this works most of the time, it can also cause problems.  Every property has specific challenges when it comes to watering efficiently and effectively. I will discuss a few of the common ones that effect watering and how to manage this.  

First, look at your property and observe how much sun or shade is affecting the landscape and the overall growth in these areas.  The areas of the landscape that receive full sun for long periods of time will need more watering than areas of partial sun or shade.

Second, soil can greatly affect how water travels, which makes knowing the make-up of the soil conditions of the property very important.  Black dirt or a good combination of disintegrated rock and humus is ideal for growth and can be the easiest to maintain a consistent watering regiment.  Clay soil is dense and made up of small particles; clay feels smooth to the touch when dry and will stick to your fingers when wet. Thick clay soils do not allow for much air and water circulation and can be a challenge when it comes to irrigation.  Watering for longer times less frequently with clay soils allows for the water to work its way into the soil and get to the root structures.  On the other end of the spectrum is sandy soils that are composed of many irregular to rounded tiny grains of sand, as opposed to the many tiny plate-like soil particles that make up a clay soil.  Water moves quickly through sandy soil and air replaces it rapidly, which makes watering these types of soils difficult. Watering turf in sandy soils require shorter more frequent watering.  This allows the water to get to the roots and reduces the amount of water wasted.

Third, just observe the landscape and alter watering times and days depending on results to establish an irrigation routine. It will take some time to work out the best watering practices for your specific property, so make notes and store them with the irrigation controller for future use.


Until next time,

Jim Schuster, Irrigation Manager at Barrett Lawn Care

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