Should You Water Grass Before a Frost?

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Water is crucial at all times for keeping your lawn lush and healthy. However, the water needs for grass change with the seasons; while grass needs sufficient water in the summer, too much water can cause damage in the fall. Knowing if it’s safe to water your lawn before a frost can be challenging due to these variations.

You should water grass before a frost if the temperature exceeds 40°F (4.44°C) to keep it safe and healthy. Wet soil insulates the grass’s roots against the freezing impact of the frost. Therefore, watering the grass before a frost strengthens it to fight damage from the cold weather.

In the rest of this article, I’ll discuss why watering grass before a frost helps prevent damage. I’ll also discuss the factors you should consider before watering grass when anticipating a frost. Let’s get started!

Will Watering the Grass Prevent Frost Damage?

Watering grass before a frost is an effective way to prevent frost damage. Frost exposes roots to freezing temperatures, which can cause them to turn brown and die. The water applied to the grass before a frost creates a barrier between the roots and the cold air.

Apart from damaging the roots, the freezing temperature of frost affects the leaf blades of grass by making them rigid. When you walk or drive on such grass, the leaf cells rupture, turning the grass brown. Watering the grass before a frost helps keep the leaf blades flexible and makes them less likely to be damaged by cold temperatures.

Here are other ways watering before a frost protects your grass from damage:

Maintaining Ice Temperature

The temperature range for protecting grass and other crops is 24 to 32°F (-4.44 to 0°C). However, the temperature can fall extremely low in the periods when frost forms. When this happens, your grass is more likely to get damaged by frost.

When water freezes, it releases energy to change from liquid to solid. The energy released is critical for keeping the ice wet and maintaining the ice temperature at freezing. If there is no water to release this energy, the ice temperature will drop, and the grass will be damaged by frost.

Heat Preservation

Water holds heat more than land (soil). Grass needs warmth to grow, and the soil provides this heat. However, when it’s cold, the ground loses its heat faster than water. As a result, watering your grass before a frost helps preserve the heat in the ground and protect the roots of your grass from freezing.

Dehydrated blades have a low heat retention capability. Therefore, as the ground loses heat due to the cold temperature, your grass remains exposed to frost damage.

Factors To Consider Before Watering Grass

Cold seasons, during which frost is most likely to form, can be quite challenging when it comes to watering grass. Due to uncertainties among most lawn owners, you may have heard sentiments such as:

  • It’s unhealthy to water grass when it’s cold.
  • Watering grass in cold weather can damage the blades.
  • It’s challenging to water grass when it’s frozen.

All these are valid concerns you should consider before watering your grass in the cold season. In this section, I’ll discuss some factors you should consider before watering your grass in anticipation of a frost.

Type of Grass

The type of grass in your lawn is a significant factor to consider before watering it in the cold season. Your grass can be cool-season or warm-season.

Cool-season grasses are hardy and can survive cooler winter temperatures. Since these grass can survive the coldness experienced in winter, they don’t need as much water as their warm-season counterparts. However, this doesn’t mean you shouldn’t water them before a frost.

Warm-season grasses are not as cold-hardy as cool-season grasses and will go dormant (turn brown) in winter. If you have this type of grass, it’s essential to water it well before the first frost to help it withstand the cold season.

The table below shows some common cool-season and warm-season grasses:

Cold-Season GrassWarm-Season Grass
Tall FescueZoysiagrass
Fine FescueBermudagrass
Perennial RyegrassSt. Augustinegrass
Kentucky BluegrassCentipedegrass
Table 1: Cool-season and warm-season grass


Never water your grass when the temperature is below 40°F (4.44°C). Temperatures below this threshold are also too cold to cut grass.

Water droplets stick on the blades if you water your grass. These droplets are immediately exposed to cold nighttime temperatures and wind chill, freezing them.

The freezing results in frozen and brittle grass blades susceptible to breakage.

You should also avoid watering your grass when the temperature is above 90°F (32.22°C). The high temperatures will cause the water droplets on the leaves of your grass to evaporate before they can be absorbed.

The Presence of Rain

The chances of overwatering your lawn when it rains in the fall or winter are high. When it rains in the fall or winter, the water supplied by the rain is sufficient to meet the needs of your grass. You should, therefore, avoid watering your lawn when it’s raining or has rained in the last 24 hours.

Overwatering your lawn will increase the chances of diseases such as root rot and fungal infections.

The Presence of Frost

It’s advisable to avoid watering your grass when the frost has already formed. Watering at this stage will only create a layer of ice on top of the frost, which can further damage your grass. The ice increases the weight and stress on the blades, weakening them.

The Right Time To Water Grass Before a Frost

The best time to water your grass before a frost is in the early morning or late afternoon. Watering in the early morning allows the grass to absorb the water before it evaporates due to the day’s high temperatures.

On the other hand, watering in the later afternoon hours gives the grass enough time to absorb the water before the temperatures drop at night.

It’s also essential to water your grass thoroughly but not to the point of runoff. Overwatering the grass can get the roots clogged due to the low temperatures and poor vaporization rates in winter. Most lawns only need 1/2 inch (1.27 cm) of water in cold weather.

Tip: Also make sure to apply fertilizer before frost to supply your lawn with the necessary nutrients.


Watering your grass before a frost protects it from damage risks like becoming brittle. However, you must be cautious not to water when it’s freezing or the temperatures are extremely cold. Doing so will cause more harm than good to your lawn.

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