Proper watering is essential for a plants and lawns to establish a healthy root system. Determining when to water and how much to water depends on several factors such as soil conditions, plant size, plant type and weather conditions. In general, the best technique for watering any plant is to water at a slow rate over a long period of time, allowing the water to penetrate deep into the soil.
The best technique for determining when to water is to observe both soil and plant conditions in the lawn and then water when the turf needs water, rather than on a regimented schedule. Frequent lawn watering often encourages shallow rooting and may predispose the lawn to increased disease and greater susceptibility to stress injury. Watering deeply and less frequently provides for improved turf growth and increased water conservation compared to light, frequent watering.
Using a lawn sprinkler, water your lawn to a depth of 4-6 inches. This amount of water will vary with soil texture, but placing several empty tuna cans under the sprinkler will allow you to determine when an appropriate amount of water has been applied. You can then determine how much water to apply to adequately wet the soil to the right depth. To avoid lawn disease, watering should be done early in the morning before the dew evaporates.
Trees and Shrubs
In order to encourage healthy root growth you need to provide enough water for it to soak the entire root ball. An open hose placed at the base of a tree with the water flowing slowly will provide needed water to the root zone. If the water is allowed to trickle into the soil gradually, it will seep down and saturate the area around the roots. A thorough watering should last 30-60 minutes, depending on the size of the root ball. If you have a group of plants in a hedge or planting bed, use of a soaker hose will allow you to water multiple plants in the same amount of time.
During the first week water your plant as frequently as if it were still in the container (once a day). For the following few months keep the soil beneath the surface moist and cool. Allow enough time between each watering so that the soil is not consistently wet and muddy, but not so much time that it becomes dry and dusty. (About once a week)
Flower and Vegetable Gardens
Annual and perennial gardens should be watered slowly and thoroughly at the base of the plants. A fine-textured mulch or soil conditioner such as peat moss should be used to help hold the moisture. Flower and vegetable gardens may require more frequent watering. Again, merely sprinkling the beds lightly each day will not be adequate for efficient water use. Saturate the areas once or twice a week during drought periods, and watch the plants closely. If wilting occurs, water should be applied more often; but under normal circumstances twice a week should be ample if a mulch is used.
Water evaporates at a much faster rate from containers than it does from the ground. Therefore, plants in containers require more frequent watering than plants in the ground. The best practice for watering container plants is to be observant and water only when the soil begins to dry. Depending on the size of the container and the time of year, this could require watering anywhere from once a day to twice a week. It is best to thoroughly saturate all of the soil inside the container by applying water at a low pressure until it flows from the bottom of the container.