How to Schedule Your Irrigation System | A Cut Above

How to Schedule Your Irrigation System

Over or under watering can be potentially devastating to your lawn or landscape. Watering too much drowns turf and plants, while under watering leads to wilting and even death. Understanding how much water you’re applying helps protect both your landscape and your investment.

Importance of Proper Scheduling

Step 1: Find Gallons Per Minute (GPM) for Each Zone

Each irrigation zone has a limited number of heads based on water pressure. Count how many heads are in each zone and identify whether they are spray heads or rotors.

Typical output:
Rotors: 1.5–3.0 GPM (use 2.0 if unknown)
Sprays: 0.5–1.5 GPM (use 0.5 if unknown)

Step 2: Determine Coverage Area

Measure the total square footage covered by each individual zone.

Step 3: Calculate Precipitation Rate (PR)

Use the total GPM and coverage area to calculate how many inches of water the zone applies per hour.

PR (in/hr) = (96.3 × GPM) ÷ Area (sq ft)

Step 4: Determine Weekly Run Time

On average, lawns require about 1 inch of water per week. Use the precipitation rate to determine how long each zone should run.

Split watering into 2–3 days per week and water early in the morning. Deep, infrequent watering promotes stronger root systems.

Step 5: Monitor and Adjust

Monitor results and make small adjustments as needed. Soil type, slope, sun exposure, and weather all affect watering needs.

For More Information

  1. Free Irrigation System Run Time Calculator
  2. Rain Bird – Irrigation Scheduling Guide