While all automatic sprinkler systems should be customized to individual lawns, there are some simple rules one should follow in order to get sufficient water to the root zone with minimal waste. There are two essential guidelines to this end:
- Deep, infrequent watering is the best possible way to water.
- Most irrigation systems output water faster than soil can absorb it.
In other words, watering lightly every day is bad for lawns and watering for one to two hours without interruption is wasteful.
When setting up a system in spring, we recommend watering every third day, starting early in the morning (at 4 a.m.). Each zone should water to the point of runoff (this is usually 5-10 minutes for fixed spray/misting heads and 20-30 minutes for rotary heads. Individual zone runtimes should be adjusted for shade, slope, competing tree roots, or other relevant conditions.
As the weather warms (late May/June), add an additional start time (but don’t increase the number of days your system runs or zone runtimes). Ultimately, your system should run through each zone every third day, and when complete, it will run through the program again. For example, a sprinkler system that waters for 25 minutes in the front yard at 4 a.m. should come on again at 6 a.m. for another 25 minutes. This pause in watering minimizes waste and allows the water to soak deeper into the soil. In the event of a severe drought, a third start time should be added. Then, as weather cools in the Fall, return to a single start time.
Notes on Adjusting Sprinkler Heads
There are many instances where a sprinkler head may seem out of adjustment when it is not.
- Heads along a driveway or walk need to over-spray a few feet onto the pavement to ensure the grass along the edge does not dry out when it is hot.
- Shrub zones usually do not cover every square foot of mulch. Water tends to diffuse through mulch areas and will adequately water the roots of shrubs.