Q: Please — when you tell someone to water a tree down about 4 feet — will you please use other parameters? How am I supposed to know when something is wet down to 4 feet? Dig a hole? I didn’t read it today, and I can’t say that you are responsible for this — but many times past over the years I have had the same reaction. It’s just that today I am finally taking the time to write and your email address is handy!
A: Watering depth can be measured in several ways including some fairly sophisticated devices, calculating the output from your drip irrigation emitters, and by using a soil probe. The soil probe is the least complex and the least expensive. This device can be as simple as a piece of rebar with a handle and a pointed end. These probes are sold in a variety of garden shops and even our Cooperative Extension office sells them to benefit the Master Gardener Program. Some are as cheap as $5 and others are a bit more expensive. By pushing the probe into the soil after irrigating you can tell approximately how deep your water is going. The dry soil will provide more resistance than wet soil so you can stop pushing when it becomes more difficult and measure how much of your probe is in the soil. It’s not as much fun as math but it can help you adjust your irrigation practices.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Email questions and photos to tucsongardensage@gmail.com
