What Temperature is Too Cold to Water Grass?

When the temperature is below 40℉ (4℃), it is too cold to water grass. Grasses enter dormancy as temperatures dip closer to freezing, requiring much less water. Although it is beneficial to water grass even in colder months, watering at temperatures below 40℉ can contribute to damaging freezes that harm or kill your grass.

Should You Water Your Grass When It’s Cold?

Watering grass in cold temperatures can greatly improve your lawn’s health. As long as temperatures are above 40℉, watering can have the following positive effects on your lawn:

• Watering during cold temperatures feeds the roots of your grass. Even dormant grass still requires water. Extended dry periods during cold winter months can damage or kill grass.
• If you have young grass sprouts without established root systems, watering is essential to keeping this new grass alive through a cold snap.
• If you water your grass during the winter, it will come back stronger, greener, and fuller in spring.

Watering during winter is also less expensive than summer watering. Due to grass dormancy and reduced heat evaporation, winter grass requires half the water summer grasses do. In summer, your lawn needs about an inch of water per week. In winter, your lawn only needs about ½ inch of water. Subtract any precipitation from your lawn’s watering needs to avoid overwatering.

When to Stop Watering Lawn in the Fall

In most regions, it’s safe to reduce watering to winter levels or stop watering entirely from mid-November through mid-March. Similar to cutting your grass when it’s cold, it’s best to curtail your watering when your grass stops growing in the fall. This is a sign that your grass is entering dormancy and needs less water.

• In regions with cold winters and heavy snowfall, stop watering in mid-November.
• In regions with mild winters, reduce watering to ½ inch per week when the grass stops growing and begins to go dormant.
• Warm-season grasses, such as Bermuda and St. Augustine, enter dormancy when soil temperatures reach 55℉ (12℃).
• Cold-season grasses, such as fescue, enter dormancy when soil temperatures reach 50℉ (10℃).

Should You Run Sprinklers in Winter?

Running sprinklers for your lawn in winter can be harmful or beneficial, depending on the conditions. Here is when and how to use sprinklers for watering lawns in winter:

• Run sprinklers in winter only when temperatures are above 40℉.
• Adjust your watering schedule. In summer, it’s common to water at 6:00 or 7:00 AM. In winter, start watering at 9:00 AM. This will help avoid cold morning temperatures that can freeze water and harm grass.
• Use this WiFi-controlled irrigation system to change your watering schedule with the seasons.
• Never water when frost is present on your lawn. Water from your sprinklers may turn to ice, which can destroy grass blades and kill the grass. Wait until the frost thaws to water.
• Do not water when snow or ice is present, even if temperatures are above 40℉. Watering in these conditions can contribute to an icy formation that is harmful to your grass.

How Cold is Too Cold for Sprinklers?

Any temperature below 40℉ is too cold to use sprinklers to water your lawn. Although air temperatures are still above freezing, water droplets clinging to grass blades will be exposed to wind chill or colder nighttime temperatures, which may freeze them solid. This can result in brittle, frozen grass. Freezing damages grass blade cells, which can kill the grass in your yard.

Should You Water Your Lawn Before a Freeze?

If there is a freeze on the forecast, water no less than 24 hours before the freeze arrives. This allows time for the water to permeate the soil and act as an insulator. This will prevent frozen topsoil and roots, which allows your grass to continue to take in nutrients even during a cold snap.

If you water less than 24 hours before a freeze, water present on grass blades may freeze, turning your lawn into an ice rink and potentially killing grass.

Watering During A Freeze to Protect New Grass

There is an alternative to watering 24 hours before freezing that should be used sparingly. It is a tactic specifically meant to protect new grass seedlings during out-of-season cold snaps.

Set a timer to water your lawn overnight for half an hour every three hours. Because the water from your tap is typically around 20 degrees above freezing, this application of warm water can help young grass from frosting and freezing. A single frost is harmless to mature grass, but can kill young grass outright, so preventing frost formation is essential to keeping new grass alive.

This tactic is best used to prevent damage to new grass from a rare frosty night in early fall or late spring. If used night after night, the excess water will drown your grass and potentially harm your yard.

Watering Grass in Winter

In southern regions with mild winters, it is beneficial to water grass at half the regular volume (½ inch of water per week instead of 1 inch) as long as temperatures are above 40℉ (4℃). Watering dormant or slow-growing grass in low temperatures prevents grass death, strengthens roots, and ensures a strong lawn return in spring.

Never water when temperatures are below 40℉ or when snow, ice, or frost are present, as this can result in frozen grass, which can be damaging or even deadly to your lawn. To avoid watering during frosty mornings, consider changing your watering schedule to begin at 9:00 AM, to allow time for morning frost to dissipate.