Homeowners often face a dilemma when cold weather arrives: whether to water the lawn or let it be. The decision depends on the specific circumstances of the environment and the lawn itself. For turf health, “cold weather” is defined as a period when temperatures are consistently below 50°F but safely above freezing, causing grass growth to slow significantly. Understanding the state of your grass and the risks involved is necessary before watering outside of the growing season.
Understanding Dormancy and Winter Hydration Needs
Even when the weather turns cold and grass appears brown or dormant, the plant is not dead; it is merely in a state of suspended growth. This dormancy is a survival mechanism, particularly for cool-season grasses like Kentucky bluegrass and fescues, which stop active blade growth when soil temperatures drop below 50°F. The root system remains alive and requires a minimal level of moisture to prevent winter desiccation. Desiccation occurs when the grass loses more water through its leaves and crown than the dormant roots can absorb, often exacerbated by dry, windy winter conditions.
A dry root zone makes the grass more vulnerable to both freezing injury and mechanical damage. Properly hydrated soil acts as an insulator, slowing the loss of heat absorbed from the sun, which moderates temperature fluctuations around the roots. Occasional winter hydration is necessary to preserve the living tissue until the next growing season, preventing the root crown—the plant’s growth point—from drying out and dying.
The Risks of Watering Near Freezing Temperatures
Applying water when temperatures are at or below 32°F, or when overnight lows are forecasted to drop below freezing, poses several immediate threats to turf health. The most serious danger is the physical damage caused by ice formation around the grass crown. When water freezes, it expands, and a layer of ice can physically crush or suffocate the delicate growth point of the plant. This ice layer also prevents the necessary gas exchange between the soil and the atmosphere, which further stresses the living root structures.
Watering too close to a freeze also risks damaging the irrigation infrastructure. Water left standing in pipes, sprinkler heads, or hoses can freeze and expand, causing lines to burst or components to crack. Excess water that runs off the lawn will freeze on walkways, driveways, or paved surfaces, creating a hazardous environment. Avoid watering when the temperature is expected to fall below 40°F within the next 24 hours.
How to Determine if Your Lawn Needs Water
Since visual cues in dormant grass can be misleading, a physical assessment of the soil moisture is the most accurate way to determine the need for water. A reliable method is the “screwdriver test,” which uses a long, flat-bladed screwdriver or a metal probe. Attempt to push the probe into the soil several inches deep.
If the probe slides easily into the soil four to six inches, the moisture content is adequate, and no watering is needed. If the soil is hard, dry, or compacted, and the probe can only penetrate an inch or two, the lawn requires deep watering.
Visual Indicators
Other visual indicators of drought stress in cold weather include grass blades that appear dull gray or blue-green instead of their typical winter brown. If footprints remain compressed in the lawn for an extended period after walking on it, it suggests the grass lacks the turgor pressure that adequate hydration provides.
Best Practices for Cold Weather Watering
If the soil moisture assessment confirms a need for water and the temperatures are safely above the freezing threshold, the method of application is important for maximizing benefit and minimizing risk. The optimal time to water a dormant lawn is mid-day, generally between 10 a.m. and 2 p.m., when the day’s temperature is highest. This timing allows the water to fully absorb into the soil and the grass blades to dry completely before the temperature drops in the late afternoon and evening.
Watering should be deep but infrequent to encourage the roots to seek moisture deeper in the soil profile. Apply enough water to achieve a moisture depth of several inches, which translates to about a quarter to a half-inch of water. During prolonged dry spells, this deep watering should only be necessary once every four to six weeks, depending on local rainfall or snowmelt. This minimal, deep hydration prevents desiccation while avoiding oversaturation that can lead to fungal issues or frozen surface water.