Correct timing for activating spring sprinklers is important for promoting robust turf health and conserving water. Starting irrigation too early can lead to oversaturated soil, which encourages shallow root growth and creates an environment where lawn diseases can thrive. Conversely, waiting too long can place unnecessary drought stress on your landscape as temperatures begin to rise.
Assessing Optimal Soil Conditions
The most reliable indicator for starting your irrigation system is the condition of the soil, not the air temperature. Turfgrass roots begin their active growth phase when soil temperatures consistently reach the 50°F to 65°F range. Soil that is too cold and already moist from winter precipitation lacks the necessary warmth for the grass to fully utilize the water. This can lead to waterlogged conditions that deplete the soil of oxygen needed for healthy root development.
The risk of frost damage remains a concern for the physical system hardware. Water expands when it freezes, meaning below-freezing temperatures can crack pipes or rupture the backflow prevention device. Wait until the ground is fully thawed to a depth of about 12 inches to ensure the entire system is safe from freeze-related stress. Experts advise waiting until at least one week after the last average frost date for your area and when overnight temperatures remain above 32°F.
This typically translates to mid-April in southern climates and potentially late April or mid-May in northern regions. Starting the system when the soil is ready for new root growth supports the turf’s natural recovery from winter dormancy.
Steps for System Preparation
Before any water is introduced, a thorough inspection of the irrigation hardware is required to prevent damage. Open the main water supply very slowly to prevent a high-pressure surge, often called a water hammer, which can rupture internal seals and weak components. Gradually allowing the pipes to fill with water keeps the pressure under control throughout the network.
Once the system is pressurized, the backflow prevention device must be checked and, in many areas, tested by a certified technician. This component is a safety mechanism that stops irrigation water from reversing direction and contaminating the main drinking water supply. After the main lines are charged, manually run each zone to check for proper function and clear any debris.
Watch for geysers, leaks, or heads that are spraying improperly due to misalignment or damage from winter ground shift. Clogged heads will distribute water unevenly, which can lead to dry spots or overwatered areas. Replacing worn nozzles or repairing misaligned heads now ensures efficient water delivery for the entire growing season.
Initial Watering Strategy
When you first begin watering, the strategy should focus on encouraging roots to grow deep into the soil profile through deep, yet infrequent, watering. In early spring, the lawn likely needs only one or two watering sessions per week, depending on natural rainfall. The general guideline is to provide roughly one inch of water per week, including any precipitation. Light, frequent watering trains the roots to stay near the surface, leaving the turf vulnerable to heat and drought stress.
Watering deeply ensures the moisture penetrates beyond the top few inches, encouraging roots to follow the water down. The best time to run the sprinklers is early in the morning, typically between 4:00 AM and 10:00 AM. Watering during this window minimizes water loss from evaporation and allows the grass blades to dry quickly, which reduces the risk of fungal diseases. Before relying entirely on an automated schedule, manually monitor soil moisture levels by probing the soil to ensure the water is reaching a depth of four to six inches.