Stopping lawn watering for the season is a gradual process based on changing environmental conditions, not a single switch. Efficient watering prevents waste while maintaining turf health, preparing the root system for colder months. This process involves monitoring the weather, observing the grass’s physical state, and protecting irrigation equipment from freezing. Watering needs shift dramatically from the high demand of summer to the minimal requirements of late fall.
Seasonal Transition: When Demand Decreases
The shift in watering frequency typically begins in late summer or early fall, driven by shorter days and cooler temperatures. As daylight hours decrease, the grass’s rate of photosynthesis slows down, reducing its overall metabolic needs. This decline means the plant requires less water to function.
Lower temperatures significantly decrease the rate of evapotranspiration (ET), which is the combined loss of water from the soil and grass blades. When air temperatures drop below 60°F, grass growth slows considerably, allowing longer intervals between watering sessions. This period is a tapering process where you reduce frequency, perhaps from three times a week to once a week.
The specific timing for reduction depends on the grass type. Warm-season grasses (Bermuda or Zoysia) enter dormancy when temperatures consistently fall below 55°F, signaling a dramatic drop in water demand. Cool-season grasses (Kentucky Bluegrass or Fescue) remain actively growing until the air temperature drops closer to 45°F. Regardless of type, supplemental water needed decreases from the summer peak of 1 to 1.5 inches per week to about 0.5 to 1 inch per week.
Reading the Grass: Signs of Adequate Moisture or Dormancy
The most reliable way to gauge your lawn’s moisture level is by observing its physical reaction to stress. The “footprint test” is a simple indicator of dehydration: if footprints remain visible for more than a few minutes after walking across the lawn, the grass lacks the turgor pressure to spring back upright. This loss of rigidity signals that watering is necessary.
Another practical assessment is the screwdriver test, which checks the depth of soil moisture. After watering or significant rainfall, a screwdriver should slide easily into the soil to a depth of four to six inches. If the soil is hard and resists penetration, moisture has not reached the deep roots. This means the grass is relying on shallow water that will quickly evaporate.
You must also account for effective rainfall, as not all precipitation is useful to the lawn. Light drizzles (less than 0.2 inches) often evaporate quickly before soaking into the root zone. Heavy downpours resulting in surface runoff also do not fully benefit the grass, as the soil absorbs water slowly. You can skip supplemental irrigation only when natural precipitation delivers sufficient water to the root zone, confirmed by the screwdriver test.
Final Shut Down: Preparing the System for Winter
The final cessation of watering is determined by the threat of freezing temperatures, which can damage the irrigation infrastructure. This mechanical shut down is a safety measure for equipment, not a decision based on the grass’s immediate water needs. The deadline for this process is typically just before the first hard frost is expected in your region.
The standard method for preparing an in-ground system is called “blowing out” the lines. This uses compressed air to physically force all water out of the pipes. This requires shutting off the main water supply and systematically connecting an air compressor to the main line. Air pressure must be carefully regulated to prevent damage, generally not exceeding 50 PSI for polyethylene pipes or 80 PSI for PVC.
The blow-out process involves opening and closing each irrigation zone valve in sequence, starting with the zone farthest from the compressor. This ensures compressed air pushes all residual water out through the sprinkler heads until only a fine mist is visible. Failure to remove all water from the backflow preventer and underground lines risks the water freezing, expanding, and rupturing components. This leads to costly repairs when the system is reactivated in the spring.