I have a sprinkler system in my yard. It waters my lawn and flower
beds. My question is how long should the sprinkler system be on and
for how often? I don't want to waste water and I'd like to save some
money on my water bill, but I don't want my lawn to burn up, either.
A. As a general rule of
thumb, most plants (including lawn) need one inch of water per week -
no more, no less - either from natural rainfall and/or your watering.
So if it rains that week and you get a half inch of water from the
rain, you would only need to put down a half inch of water. The best
way to keep track of how much rain you get is to set out a rain gauge.
For automatic sprinkler systems, as well as manual
sprinklers that you set out yourself, I have a tip for determining
how long you need to water to get one inch of water. The next time
you water, get some small empty cans like tuna fish cans and set them
at different locations under the sprinkler. Look at your watch and
take note of the time. Turn on the sprinklers and keep an eye on the
cans. When one inch of water collects in the cans stop the sprinklers
and figure out how long it took. That's the amount of time you'd need
to put the sprinklers on if there was no rainfall that week.
Another important consideration when watering is how
often to water. It's best to do just one thorough watering per week
instead of several light waterings. One thorough watering weekly
encourages the plant's roots to go deep into the soil where they're
less likely to dry out if a hot, dry spell hits. Short, shallow
waterings cause the roots of the plant to grow near the surface where
they will dry out quickly.
The best time of day to water is early morning. Water
is a valuable commodity and by watering early less water is lost to
evaporation. With the misting-type sprayers that shoot up in the air,
I've heard that 40 percent of the water is lost to evaporation.
Early-morning watering also means less diseases on plants since the
leaves have a chance to dry off quickly. Many plant diseases are
spread by water.
To conserve and avoid wasting water, it would be a
good idea to add to the sprinkler system any type of sensors that
shut down the sprinkler system when it's raining. If there's a rain
gauge or moisture sensor that shuts the system down when you don't
need to water, that would be a good idea to add as well.