Why Do Farmers Spray Water On Crops Before A Frost

Crops are like children to farmers. Like parents, farmers remain aware of the weather and plan severe calamities to lessen crop damage. Spraying crops with water is one of their techniques, which may seem odd. When the predicted lows are just below freezing, irrigation sprinklers can be used to prevent plants from freezing.

Why Do Farmers Spray Water On Crops Before A Frost? When the low falls below the temperature, you can stay protected from; irrigation will cause significant damage. Understanding more about the underlying physics of water and what transpires when it transforms from a liquid to a solid is necessary to comprehend how all of these operate.

Various concepts, from physics to chemistry, are discussed here. Although relative thermal lean heat and ice insulation or freezing delay are discussed separately, the functional connection between them is certainly not denied.

Why Do Farmers Spray Water On Crops Before A Frost?

Crops are harmed when they are exposed to low temperatures. When ice crystals form inside cells, they cause more damage. Ice forms on the outside of leaves at temperatures ranging from 0°C to -2°C, causing them to become dry and brittle.

Freezing damage is more common when temperatures fall below -2°C. Ice crystals form inside plant tissue at this temperature, rupturing cell walls and membranes. Furthermore, freezing injury occurs in all plants due to ice or frost formation. They cause significant damage when ice forms inside plant tissue and injures plant cells.

Different levels of freezing temperature

There is a clear difference between a Frost Advisory and a Freeze Warning. A frost advisory is issued when a temperature drop is predicted between 2.22° Celsius and roughly 0° Celsius. On the other hand, a freeze warning is typically issued when there is at least a dangerous likelihood that the temperature will drop to zero degrees Celsius or lower.

Here you must know that the frost temperature for plants is 0° Celsius. Around that point, cold temperature levels also affect plant health. Here, three different ranges have been shown with their botanical harms.

Mild freeze:

  • -1.667° Celsius to 0° Celsius 
  • It kills tender plants. 

Moderate freeze:

  • -3.889° Celsius to -2.222° Celsius
  • It’s caustic to many plants. 

Severe freeze:

  • -3.889° Celsius
  • It severely damages most of the plants.

Frost advisory and a freeze warning requisites

  • Cover

Cover exposed plants with a blanket plus plastic and anchor them with pebbles, bricks, or dirt to keep the heat retained. 

  • Mulch

To reduce heat loss and conserve moisture, add mulch to the soil around the roots of plants. 

  • Water

Water if no rain is forecasted.

The latent heat chemistry 

Farmers who spray their crops with water benefit from the energy transfer that occurs when water changes state. Water is made up of one oxygen atom and two hydrogen atoms. Because the oxygen atom is slightly negatively charged and the hydrogen atoms are positively charged, they tend to stick together and form hydrogen bonds.

Ice melts into a liquid and uses energy to break the hydrogen bonds. When ice cubes are placed in a glass of water, they melt, and the original liquid cools. Because the water expends energy to undergo the phase change, it cools.

The same thing happens when water freezes solid. When hydrogen bonds form and water solidifies, energy is released. This is known as the latent heat of fusion. 

Crops may fall under frozen death when temperatures drop below freezing. Farmers then frequently spray trees with water near 0 °C when frost is unavoidable. Despite its absurdity, the cold water effectively heats the plant body.

Because the water freezes at 0 °C and there is no temperature change, the heat released is referred to as latent heat because it is “hidden” or is not visible.

Water in the cells freezes slightly below zero degrees Celsius, but if trees are watered at zero degrees Celsius, the heat released as ice forms on the plant skin prevents damage.

The Specific heat concept

In severe winter, if the highest temperature falls below 0° Celsius, the water in the fine capillary and stomata would freeze, causing the veins to burst due to an increase in the volume of water on freezing resulting in the death of the plants.

When the fields are filled with water, then due to its high specific heat capacity prevents the temperature in the surrounding areas from falling below 0° Celsius.

The moist ground concept

Technically, irrigation also thwarts frosting phenomena in another way. There are more air spaces in dry soils, which inhibit heat transfer and storage.

Wetting dry soils improve frost protection during dry years. The goal is to keep the soil water content near field capacity, which is usually the water content one to three days after thorough wetting. 

This could also be due to moist ground remaining warmer than dry ground. Thoroughly water the plants if it isn’t going to rain before the freezing temperatures arrive.

It may appear illogical. However, a moist environment retains more heat than dry soil. It was watering the night before the freeze insulated the root structure of the grass and plants, lowering the risk of cold injury.

Not total freezing, but it’s the time-delay factor

The rate of heat transfers from your plants and the ground around their roots is low if the temperature is not far below freezing. Because of the high heat of fusion, it will take a very long time for most of the water to freeze if there is a lot of it.

The plant may survive the night without suffering too much harm. Additionally, the second night will kill them if it doesn’t warm up enough the following day because it begins close to freezing.

Ice as the emergency insulator

While all may be true, a better answer can also be found through another diverse thought. When water freezes, it emits heat. Consider when you have to place water in a cold place to freeze it. You must remove the heat.

So, if your plants have a thin layer of water that freezes, it helps keep them warmer. Furthermore, because ice is an excellent insulator, it will aid in keeping the plant warm, preventing the chilly pangs of cold.

Chemical bond theory

It has much more to do with chemistry than physics because energy is required to form and break chemical bonds. Essentially, hydrogen bonding between water molecules is the most significant intermolecular force. When water solidifies, hydrogen bonds release energy into the environment as they form.

Therefore, as water starts to freeze, hydrogen bonds form, which release energy into the atmosphere and warm it. Because the water will keep your plants warm as the temperature drops, spraying them with water before a cold night will prevent frosting and the subsequent death of said plants.

Problems of alternate ways to prevent plant frosting

Plants can also be effectively protected from a freeze by being covered with a sheet or blanket and mulching. All these serve as immediate insulation and arrest warm ground air from entering the area around the plant.

Never use plastic to cover a plant because plastic will harm the plant. To protect the plant from the plastic, place a cloth barrier in its path. However, this method becomes time-consuming and expensive if the area is significant or not continuous. The best approach in this situation would be irrigation in less time.

Mystery or chemistry- quantifying matters

In this regard, there is a broad scope of research and development. Why it occurs or, more precisely, how it works depends on the fact of scientific proof researched in the laboratory. The effectiveness of the various potential mechanisms at keeping the plants from freezing will also be thoroughly examined. given that anyone can think of several reasons as,

-More water means more time to ice up or freeze; 

-Enhanced heat energy required to build bonds at the freezing point; 

-Thwarting evaporation from the plant bodies; 

-Scattered water might be hotter than the surrounding air, plant body, etc. 

But quantifying them is another difficulty. So concretely speaking, you must take a theoretical position with evidence over the detailed experiments of scientists.


The way farmers consciously use overhead irrigation to safeguard their crops in the event of a freeze. The fruit buds can be protected when the temperature is dangerously low. Heat is released as the water freezes.

The plant body will receive energy in the form of heat as the liquid water layer freezes, protecting it from the effects of the cold. This is why farmers turn on the water sprinkler systems when a frost warning is issued. Spraying the plants with water before a chilly night will stop freezing injuries and even death. The way to protect nature exists in nature itself.

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