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Soil Probes

Determining when to water is as easy as 1-2-3, but first you need to do a little "soil searching"

Water availability in soil is different depending on various conditions- for example, how much water the plant uses, light, wind, heat, and soil composition. Because of varying conditions between yards and even within yards, the watering schedule your neighbor uses may not be the schedule you use.

To determine how much water is in the soil, all you need is a thin (1/4- 3/8 inch) 2-3 foot long metal rod. A piece of rebar with a handle can be used, or even an irrigation turn key with the "U" clipped off.

Simply put, when the rod is gently inserted into the soil, it will stop when it reaches dry soil. If you hit a rock or another solid object, try another place.

The chart below will tell you when to water:


Root Zone

Probe Depth

Water Now

Wait Before Watering

You Have Overwatered

Lawn (6"-12") 0-4" 5-12" over 12"
Garden (6"-12") 0-4" 5-12" over 12"
Shrubs (12"-24") 0-4" 5-24" over 24"
Trees (12-36") 0-4" 5-36" over 36"

As you can see, water to a depth of 1 foot each time you water a lawn, 2 feet for a shrub and 3 feet for a tree. When you can't push the probe into the soil more than 4 inches, it is time to water. If your probe goes in over the recommended depth- you are just wasting water.

Deep and infrequent watering is as easy as 1-2-3!

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Cochise County Cooperative Extension
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Last Reviewed and Updated: March 14, 2016
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