There are two primary skills involved in watering plants: knowing how much water to apply at each irrigation (see How Much Water to Apply), and knowing when to water. There are many methods for knowing when to water, some of them very sophisticated. The method described here is one of the simplest and easiest to learn, and it always works. The first step is to dig a hole into the root zone of the plant, from 2 to 6 inches deep. In loose soil you can dig a hole with a finger. Otherwise use a trowel or a shovel. Then feel the soil in the hole. Dig a new hole each time you check. In this book, plants are divided into 3 watering categories: those that can't tolerate drought, average plants, and those that can't tolerate wet soil. When the soil reaches a certain level of dryness, it is time to water again. Plants that can't tolerate drought: The soil in the root zone is moist but not wet. When you touch it, it makes your finger damp but not muddy. If you squeeze a ball of this soil, water will not run out.
Average plants: The soil in the root zone is just barely moist. When you touch it, it feels cool and moist, but does not dampen your finger. Most soils are crumbly at this stage, but not dusty.
Plants that can't tolerate wet soil: When it is time to water, the soil in the root zone feels completely dry. It is not cool to the touch, and it is probably dusty. It is important to water these plants as soon as the soil reaches this state. Although they can usually withstand long periods of drought, they grow much better if they are watered regularly.
