I’ve been working on improving the appearance of my lawn. One of the most important things to do is to water it properly.

Lawn Watering Parameters:

• Amount (inches) of water per week
• Frequency on lawn watering
• Distribution of water over the lawn

Amount of Water:

Most authorities recommend watering 1 to 1.5 inches per week.  If you want to break it down further, you match the amount of water to evapotransporation  losses.  Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants. These numbers are available from various websites.  Examples of things that affect the evapotranspiration rate are temperature, wind velocity, amount of sunlight , plant growth, and characteristics of the top soil layer (eg. mulch).  So on a 90 degree, sunny and windy day, more water will be lost than on a cool, calm, cloudy day.  They recommend an average of only 0.5 inches of water per week during winter.  In order to put the right amount of water down, you need a way of measuring it.  That is where the rain gauge comes in.

AcuRite Rain Gauge

Frequency of Watering:

The general guideline is “Deep and Infrequent”.  You want to water to a depth of 6 inches.  This encourages the establishment of a deep healthy root system.  But then you need an adequate dry interval to allow aeration of that root system.  If the dry interval is not long enough, the grass will be at high risk of attack from fungal diseases.  So, twice a week is a good average schedule with a range of 1 to 3 times a week.   The type of soil you have influences this as well.  Watering schedules for newly seeded or newly sodded lawns are a different matter.

Placement of Rain Gauge:

For rainfall measurement, the rain gauge should be placed away from buildings, overhanging tree branches, and other obstructions.  You want to catch all the rain, but only the rain.  Knowing how much rainfall has occurred, you only have to apply the deficit (if any) when you water.

For measurement of water applied by irrigation, you need to measure the inches of water applied at a known time interval (so you can calculate the hourly rate) at multiple locations within the lawn.  Because each sprinkler head can have a different flow nozzle rate and the spray patterns of the sprinker heads overlap, the distribution can be quite uneven.  One area may get too much water and another, not enough.  Knowing the current distribution, you can adjust it by altering the spray patterns of the sprinklers and replacing sprinkler flow nozzles with those of higher or lower flow rates, to even things out.

The AcuRite Rain Gauge is available on Amazon for $8.27.   It can be read from inside my house clear across my deck.

Do You “Need” This ?:

Why not just watch the news or read the newspaper to find out how much rain fell?  All you have to do is to watch one weather report to see that the amount of rain that falls is highly localized.  The rainfall measured at a weather station near your house can be very different from what falls at your house.  This Gauge appears highly accurate and eliminates relying on data from a different location with a different amount of rainfall.  Also, the weather report isn’t going to tell you the distribution of irrigation water application across your lawn.

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