Achieving an efficient landscape requires precision, applying a specific volume of water, such as one-half inch, rather than using an arbitrary timer setting. The run time needed depends entirely on the unique output of your sprinkler system, requiring a personalized calculation. Understanding this relationship between water volume and the application rate is the foundation for conserving water and promoting deep, resilient root growth.
Understanding Water Volume Versus Time
Targeting a specific depth, like one-half inch of water, shifts the focus from an arbitrary timer setting to a quantifiable volume that benefits plant health. Watering by the clock often leads to shallow, frequent applications, encouraging roots to remain near the surface and making plants vulnerable to drought stress. Applying a half-inch of water correctly pushes moisture deeper into the soil profile. This encourages the turf’s roots to grow downward, creating a durable underground structure that can access moisture reserves. Focusing on volume also minimizes water loss from surface runoff, which occurs if water is applied faster than the soil can absorb it.
The Catch Can Test Determining Precipitation Rate
Determining the exact amount of water your sprinklers deliver requires a simple field audit known as the catch can test. This process calculates your system’s precipitation rate, which is the amount of water applied over a given area, expressed in inches per hour. You will need straight-sided containers, such as tuna cans or specialized rain gauges, and a ruler. Place between six and twelve containers randomly across the area served by a single sprinkler zone, ensuring they are not placed too close to the sprinkler heads.
Run the sprinkler system for a short, precisely timed duration, usually 15 minutes. After the run time is complete, measure the depth of water collected in each can, recording the measurement to the nearest eighth of an inch. Add all measurements together and divide by the total number of cans to find the average depth collected during the 15-minute test period. To convert this average depth into an hourly rate, multiply the average depth by four. For example, an average collection of 0.25 inches in 15 minutes translates to a precipitation rate of one inch per hour.
Calculating the Exact Run Time
The precipitation rate derived from the catch can test provides the necessary variable to calculate the exact run time for one-half inch of water. The formula is straightforward: the desired water depth divided by the precipitation rate equals the required run time in hours. If your test determined a precipitation rate of 1.2 inches per hour, dividing the target of 0.5 inches by 1.2 inches per hour yields 0.416 hours. To convert this result to minutes, multiply by 60, which gives a precise run time of 25 minutes.
For a system that applies 0.6 inches per hour, reaching the half-inch target requires dividing 0.5 inches by 0.6 inches per hour, resulting in 0.833 hours, or 50 minutes. This calculated time is specific to your system’s current performance, but external factors may cause slight fluctuations. Changes in water pressure or significant wind during irrigation can slightly alter the measured precipitation rate. Therefore, the calculated time serves as the accurate baseline for your sprinkler controller programming.
Implementing an Efficient Watering Schedule
The calculated run time for one-half inch of water must be incorporated into an efficient schedule that maximizes absorption and minimizes waste. The optimal time for the sprinkler system to run is during the early morning hours, typically between 4:00 a.m. and 8:00 a.m. Watering during this cooler period significantly reduces the amount of water lost to evaporation before it can soak into the soil.
A technique known as “cycle soaking” is often necessary to ensure the full half-inch volume is absorbed, especially in dense clay soils or areas with slopes. This involves breaking the total run time into two or three shorter segments, allowing the water to soak in between each cycle. If the calculation determined a 30-minute run time, program the controller to run for three 10-minute cycles, with a 30-to-60-minute pause between each segment. This pause allows the water from the first cycle to penetrate the surface, preventing runoff and ensuring subsequent applications move deeper into the root zone. Watering deeply and infrequently, such as two to three times per week during peak summer months, promotes robust and drought-tolerant turf.