The Moisture Meter

An accurate answer to your watering question

Bulletin #1012

Horticultural Observations for Healthier Landscapes

Tired of getting different answers to your question "How often and how much should I water?"

A trained and qualified irrigation or horticultural specialist knows that the answer is not typically so simple. Why? Because the primary factor in watering is the soil, And soils vary. Then we need to consider the sun vs. shade aspects, the type of plant, and sometimes factors like water coming from a neighbors' landscape.

◊ Watering Recommendations

◊ Moisture Meter Characteristics

◊ Moisture Reading Before Watering

◊ Moisture Reading After Watering

◊ The Keys to Good Watering

Watering Recommendations

We have made typical recommendations for watering and presented these in our Bulletin #900A (shrubs & tress) or #900B (lawn) "How much should I water?" These are ONLY typical and may sometimes be wrong for the location and plant in question. There is a way, however, to check to see if these recommendations are going to work for your plant and soil, before the plant dies. The way is to learn the proper technique and then use a moisture meter.

Moisture Meter Characteristics

Most Moisture Meters are inexpensive and do not even require batteries, as is the case with the meter to the right.

The dial at the top provides a digital reading of the relative moisture in the soil based on conductivity.

Moisture Reading Before Watering

Plants need to breathe! Too often we water our plants before their roots are getting oxygen. By reading surface soil moisture prior to watering, you can know how to prevent root suffocation. If your meter reading exceeds 6 at a depth of three (not deeper) inches, then the plant should NOT be watered yet. It's normal for the soil, at a deeper level to retain water, and so read high, even though the plant may be ready for watering. TO CHECK OVER-WATERING, read at a depth of ONLY 3 inches, just before watering.
(top)

Moisture Reading After Watering

Adequate watering quantity (or minutes) can be checked by testing soil moisture, all around the root system at a depth of 6 to 7 inches, one to two hours after watering. The reading should be maximum or "10". A low reading this early would indicate that you are not watering long enough to saturate the soil. TO CHECK FOR UNDER-WATERING, read at a depth of 7 inches three hours after watering.
(top)

These are two entirely different types of readings to determine two different issues!

The Keys to Good Watering are:

1) Water slowly and long enough to saturate the soil deeply.

2) Water the entire area of the root system, not just at the plant base.

3) Do not water too often.

Your moisture meter can confirm all three of these parameters for you! You need an estimate to begin with, but then you should check, and see how the soil actually reacts to the estimated schedule.
(top)