K-State Research and Extension

Keys to Watering in Kansas City

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Water is the basis of life. All living things depend on fresh water including us and our landscape plants. Improper watering of plants is probably the number one killer as we often apply too little or too much. Learning how to properly water is one of the most difficult gardening tasks to learn. Teaching someone how to water is also the most difficult task.

Why is something so basic so difficult? The problem is simple; we cannot see what is going on six to eight inches below the soil. We are often just left to guess whether the plant needs to be watered. Learning the principles of watering is the first step.

Learn the root zone
Watering is about keeping the plant’s root-zone hydrated. Roots of plants develop from just below the surface to many feet deep into the soil, depending on the plant. The majority of all plants, whether a stately oak tree or a tomato plant, has feeder roots picking up the water and are mostly located within the upper six to eight inches of the soil.

It is for this reason as gardeners we focus our attention to watering in this shallower layer of the soil. With that being said, some plants have the ability to pick up water more deeply in the soil. Some more drought tolerant plants can survive on less water, while others need a more consistent level of moisture, which is part of the problem when learning how to water.

Balancing air and water
Roots need the proper combination of oxygen and water in the soil to survive. It is creating this balance that results in best growth. More water in the soil means less oxygen; less water means more oxygen. If either is off then the plant can show signs of wilting.

How much to apply
Based on the location of the roots and air exchange, this is my recommendation for watering; water deeply and less frequently. Soak the root profile six to eight inches deep and do not reapply until it has dried out. This method follows the standard recommendation that plants need about one inch of water about once a week.  

It takes an inch of water to soak our clay soils about six to eight inches deep, and under normal conditions, a week to dry out. Of course there are variables such as rainfall, heat and wind — all that make watering confusing.

Simple check
The best way to know when to water is just to check. Simply dig down a few inches in the soil around the plants. If it feels moist, don’t water; if it feels dry to the touch, water. How simple is that? As you become more experienced it almost becomes second nature. Remember, the more you do something the better at it you become. Don’t be afraid to get your hands dirty and learn your soil and plant needs.

Hopefully by learning these principles of watering you will feel more empowered and take some of the mystery out of watering.