One of the biggest lawn care issues I see on a weekly basis is overwatering the lawn. It is safe to say there is a large portion of homeowners who have no control over their sprinkler system or how to use it effectively. The sprinkler runtimes are likely set by their irrigation service upon start-up and never adjusted or monitored, a "set it and forget it" approach. I regularly see sprinklers on before, during, and after rainstorms.
Granted, I live in the Northeast where water is cheap and there are no watering restrictions or drought conditions, but over-watering is bad for the lawn and will make it susceptible to outside pressures like drought, insects, weeds, and diseases besides the obvious waste of water.
Get Control of Your Sprinkler System
Proper watering is knowing how to use your sprinkler system efficiently. When used properly, your sprinkler system will save you money while keeping your lawn beautiful and healthy. Most lawn sprinkler systems are not that complicated and should be fairly easy to figure out. From there, it is important that your system is equipped with rain sensors to turn the system off in the event of a rainstorm during scheduled watering, Knowing how to pause your system from its normal routine is important when rain is imminent and after periods of rain when the soil has enough moisture. Fine tuning the system and knowing how it operates will benefit the lawn and save money.
How much water is enough?
The rule of thumb for watering turf has generally been one inch of water per week. This number more or less refers to the standard Kentucky bluegrass lawn which is the quintessential lawn of the American suburb. Unfortunately, that grass type and its water requirements are not suitable, desirable, or even legal in many parts of the country.
One inch of water per week is a decent average for the spring and fall months but it's the hot, dry months of summer when one inch of rain per week is only achievable with supplemental watering either with an automatic sprinkler system or a hose/sprinkler set-up.
Lawns consisting of modern varieties of fescues, rye grasses and even Kentucky bluegrass are able to withstand somewhat lesser amounts of water, especially when managed with drought in mind. Improvements are continuously being made to grass cultivars including drought tolerance and insect and disease resistance. A well-managed lawn (even a notoriously thirsty lawn of Kentucky bluegrass), made up of newer varieties of turf will survive on much less than one inch of water per week making it possible to grow a lawn in areas with water restrictions or drought conditions.
How much water is too much?
An over-watered lawn is likely to be plagued by a host of negative results with the outcome being an unhealthy lawn susceptible to weeds, diseases, and insect damage. An over-watered lawn is often a gateway to a loop of turf problems and expensive chemical treatments that will not go away unless the underlying issue (over-watering) is dealt with.
A healthy lawn should be a little on the thirsty side, always sending roots deeper into the soil. The deeper the root system, the healthier and more resilient the turf. This is why an ideal watering is deep and infrequent (mimicking natural rainfall) rather than shallow and often. An overwatered lawn will likely have a shallow root system since there is no need for the roots to travel for water - it is always there, close to the surface. A shallow root system is more susceptible to insect damage and even heat stress since there is less water holding capacity within the root system.
An automatic sprinkler system would best be used sparingly by a homeowner, only to supplement rainfall during the hot months of summer. It should not be operated before anticipated rainstorms, during rainstorms, or after rainstorms.
This is a waste of water (money), time, and will contribute to an unhealthy lawn. Sprinklers operate most efficiently when used at night. The ideal time to water is in the pre-dawn hours when there is less wind, it's cooler, the water has a chance to penetrate to the root zone, and the moisture doesn't sit on the plant for too long and create disease conditions.
What about not watering enough?
Anyone who does not apply supplemental water to their lawns knows that a hot, dry summer can turn a lawn brown over time. Grass that is stressed from lack of water will go dormant - not die. When cooler temperatures and more frequent rains return a well-managed lawn will make a complete recovery.
During times of drought, stresses on the lawn can be lessened by mowing less frequently, mowing at a higher height of cut, and staying off the lawn. The key to riding out periods of drought is proper cultural practices and sticking to a good lawn care program.