The basics of watering plants

The basics of watering plants

The amount of water a plant needs depends on the type of plant, soil, location and the weather including temperature, humidity, and wind. It is easy to see why plants can be over-watered or under-watered.

Some methods, including hand watering and some sprinklers, make water puddles or run off long before the soil receives as much water as it needs. Many gardeners stop watering when the soil surface becomes soggy or when water starts to puddle or run off. This practice only wets the top few inches of soil. Because the rate of water absorption into the soil is slow, it may take several hours or days to wet some types of soil 3 - 4 inches deep. To water deeply and prevent run off, apply water at the same rate at which it enters the soil. If your irrigation system cannot be adjusted to apply water slowly, water until run off begins, stop watering for about an hour, then water again, until the soil has been wetted as deeply as necessary.

Each time you water, apply enough to wet the soil to the bottom of the root zone. Water is measured in inches. If a tin can is placed on a lawn when the sprinklers are turned on, the soil receives an inch of water when the water in the container is one inch deep.

There are two primary variables involved in watering plants: how much and when. There are many ways of knowing when to water, some of which are very sophisticated. Here is one of the simplest and easiest to learn.

First, dig a hole into the root zone of the plant, from 2 - 6 inches deep. In loose soil you can dig a hole with your finger; otherwise, use a trowel or a shovel. Second, feel the soil in the hole. Dig a new hole each time you check. When the soil reaches a certain level of dryness, it is time to water again.

When watering container plants, apply enough water so that some drains from the bottom. Drainage water should flow freely away from the container so that water does not collect around the base. If the container is sitting in a saucer, wait for all the water to drain through (10 - 15 minutes), and then empty the water from the saucer. Sometimes the drainage holes become blocked and water accumulates inside the container rather than flowing out. Make sure the container drains after watering. If not, poke a stick in the drainage hole to loosen compacted soil. Water again when the soil just below the surface is barely moist.

In large containers (10 - 12 inches or more), water when the soil 1 -2 inches below the surface is barely moist. Plants in containers without drainage holes are difficult to water properly. Water accumulates in the bottom of the container, causing root rot. If the soil in the container becomes too dry, it may be difficult to re-wet. Instead of penetrating the soil, the water runs down inside the edge of the container and immediately drains out the bottom. To wet the soil, soak the container in a tub or sink full of water for a few hours. The rim of the container should be submerged.