Using a sprinkler system wisely can pay off for you, your plants and the environment. Paul James demonstrates how to water properly and responsibly no matter what kind of delivery system you use. The trick is to supply your plants with optimum moisture without wasting water. James estimates that 75% of automatic sprinkler systems are not programmed properly, killing millions of dollars of landscape plants and wasting millions of gallons of water each year.
Many variables will affect how much and how often watering is needed, including the type of plants and soil you have, sun exposure, water pressure, the type of sprinkler head you use, air temperature, humidity and even the wind. James outlines the best ways to deliver water effectively and efficiently:
- Evaluate the water needs of each bed or zone. For crape myrtles and ornamental grasses, which don't need as much water and like to dry out somewhat between waterings, set your sprinkler system for a 20-minute cycle. Ferns and shade-loving woodland plants, on the other hand, need a 40-minute cycle. You can use these as starting points and fine-tune your settings later.
- Measure how much your system is actually delivering. To test the water volume, place a few coffee cups on the ground in each test area, then turn on your sprinkler for a normal watering cycle. You should be providing two inches of water per week for moisture-loving plants and one inch for the dryer plants. Position the sprinkler heads so that you're not delivering water to your driveway, patio or to the street.
- Estimate how much water you soil is absorbing. Clay soils, which tend to hold water and drain slowly, don't need as much water as sandy soils that drain quickly. To test how long your soil is holding water, wait 24 hours after watering and dig a few narrow holes in different parts of each bed or zone. Dig the holes about 12 inches deep and be sure the soil is moist 10 to 12 inches from the surface (where 90% of plant roots are found). In three more days, and still without additional watering, repeat your digging procedure and verify that the moisture has drained off into the subsoil.
- Decide how often to water. Many people set their sprinkler systems to water on a regular schedule, such as Monday, Wednesday and Friday. This could spell big trouble, says James. Plants should be watered according to need and the weather. Plants growing in full shade ordinarily don't need to be watered as often as those growing in full sun. If it rains, or if there's a lot of cloud cover for several days, plants may not need to be watered at all.
Most sprinkler systems have a rain switch on the control box, which turns the automatic mode off without affecting the programming; most people don't remember to turn it on, however, and on rainy days many sprinkler systems are running. James operates his sprinkler system in the manual mode rather than set the system to water at predetermined days and times. He operates it only when his plants need to be watered, which is roughly once a week during all but the hottest months of summer when he waters twice a week. James lives in a humid area and waters early in the morning to minimize the threat of fungal diseases. Operating the system in the manual mode also allows you to skip certain zones that don't need any water and advance to zones that do.
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