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Using Hot Water on Plants: What you should know!

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Using hot water on plants has some pretty useful applications that you might have never thought of and the temperature of the water can cause both good and bad effects depending on the use.

Hot water can be used for cleaning leaves if the temperature is below 120° Fahrenheit. It effectively removes sticky stains and common leaf pests. Above 120° Fahrenheit, the water can cause leaves to wilt, reduce microbial activity as well as nutrient availability in the soil. 

Boiling water (212° Fahrenheit), can also be used to remove weeds from your garden, for example. The hot water kills the roots of the weed while leaving your plants intact. Furthermore, heat kills most fungus spores that cause diseases, bacteria, mites, and insects.  

In this article, you’ll learn how using hot water on plants can help improve their appearance and what you need to know for effective use on plants.

Using Hot Water on Plants

Is Hot Water Good for Plants?

Using hot water on plants is one of the ancient stratagems to kill various pests and get rid of other contaminants. It does not harm plants if used once in a blue moon. 

If you think your plant soil contains impurities or chemicals, you can unhesitatingly water your plants with hot water. It will help your soil to fight out the contaminants it has. 

Hot boiling water also kills the weeds and unwanted plants that grow between the pavers or sidewalk cracks. 

So, yes, hot water definitely has good effects. But, remember one thing, i.e., beware of watering the leaves and the crown area of plants with hot water or else, it might put them in much danger. 

You can boil your cold water and use it to water your plants. Warm it less than or up to 120°F. Your plant can easily tolerate this much temperature. This much hot water does not harm your plants but eradicates pests and pathogens. If the temperature exceeds, it might hurt the plant as well as the soil.

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MyLifeUNIT Plastic Watering Can

How Much Hot Water can Plants Tolerate?

Plants can tolerate hot water but, obviously, to a certain extent. 

Plant experts suggest that plants can bear a maximum temperature of 120° Fahrenheit or 49° Centigrade. 

But, if you warm water more than the mentioned temperature, it might cause the plant to wilt or droop. 

On the other hand, florists state that sometimes hot water is used to resuscitate wilted flowers. In such a case, the water can be warmed until it turns 110° Fahrenheit. 

Again, to restore the wilted stems of woody plants, hot water of 180° to 200° Fahrenheit is deemed the best. 

But, whatever temperature you give your plants, you must be mindful that your plant’s root ball temperature does not rise above 115° Fahrenheit because higher temperatures may critically damage your plant.

How Does Hot Water Affect Plants?

I have already mentioned in the last point that boiling water may affect the plant. Now, to give you a more comprehensive view of that, I will discuss all the possible harms that a plant may suffer. 

Hot water may damage the cell structure of plants. After using hot water, the plant cell fails to keep up the previous turgidity and hold water. 

Hot water makes plant roots incapable of absorbing water and nutrients from the soil. 

Boiling water often causes the cuticle on plant leaves to melt away. This increases the exposure of plant leaves to diseases, pathogens, and pests more than usual. 

The foliage of plants may get scalded by hot water. If such a thing happens, the tips of the plant leaves appear burned, and the leaves may get shriveled.

Last but not least, the high temperature of hot water affects the oxygen intake capacity of plants. It, therefore, decreases the rate of respiration.

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purvied for stronger leaves

How Does Hot Water Affect Soil?

Not just the plants, hot water affects the soil as well. Here’s how.

Most notably, the high temperature of hot water causes water to evaporate rapidly. As a result, the proper movement of adequate water inside the soil profile gets impeded. 

For your better understanding, here is a categorical list of soil elements about how those are affected by the heat of boiling water.


Continual use of hot water may create cracks in the soil. Moreover, it may cause the sand particles to break down. The clay minerals in the soil get dehydrated due to the extreme temperature. Silt-sized particles increase while sand-sized particles decrease in the soil. 

The high temperature even causes the soil to dry out faster than usual, making the soil more compacted.   


Besides the harmful bacteria and pathogens, the hot water used in the soil kills many beneficial organisms. High-temperature spoils the eggs of the insects and the friendly microbes. 

The extreme heat also leads to the denaturation of the enzymes of these microbes and renders them useless. It even harms the cell membrane of these microorganisms. As a result, those become sterile and cannot anymore add to the fertility of the soil. 


In addition to killing beneficial organisms such as rhizobia, mycorrhizal fungi, actinomycetes, and diazotrophic bacteria, hot water also reduces the availability of nutrients. 

These bacteria help increase the nutrient concentration in the soil by breaking down the organic material.

The nutrient availability in the soil is affected by pH and a lower pH will favor higher nutrient levels. Although it is proven that an increase in temperature reduces pH, this decrease in pH does not help increase nutrient availability in soil.

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Trazon Soil pH Meter 3-in-1 Soil Tester Moisture

Can Hot Water Prevent Pests?

Hot water can prevent various pests and pathogens.

Why follow the expensive methods to fight out weeds that keep infesting your dear plants? 

Just try out this inexpensive as well as an effective way of using hot water to prevent pests.  Believe it or not, it works wonders. 

Are your plants suffering from the infestation of aphids, scale, mealybugs, or mites? 

Here’s the easiest way to deal with them.

Warm water until it reaches 120 degrees Fahrenheit. Now, pour it into a bucket.  Then, submerge the pot into the water kept in the bucket. Wait for a couple of minutes and pick it up. This is the most effective way to say goodbye to the stubborn root mealybugs

Again, if it is crawlers or nymphs that you want to give your plants relief from, follow the method of spraying.

Spray the boiling water on your plants for not more than 5 minutes. Now, you have to spray cold water on them for 1 minute. 

Repetition of the entire process thrice might be a permanent solution to get rid of crawlers. 

Cleaning Plants With Hot or Warm Water:

For cleaning potted plant leaves or any other plant part, you can use lukewarm or slightly hot water. But, never use boiling water. It might kill your plant or strip the plant leaves off their cuticles.

Smaller plants or plants that have smaller leaves can be dunked in lukewarm water. This is the method of washing off all layers of dust. Do consider holding the soil and the plant while dunking the plant by inverting the pot.

You can wet your potting soil beforehand to avoid the mess of soil being scattered. 

Do remember drying the leaves using a napkin, soft towel, or cloth. Forgetting this step might leave water spots on the plant’s leaves, compelling you to clean your plant again. 

Again, the larger plants that can in no way be dunked into water are cleaned in another way. This is followed mostly when the plant is abnormally dirty and when thick layers of dust cover the plant parts. 

The appropriate amount of liquid soap is mixed with lukewarm water. Then, it is time to kick out dust by thoroughly misting the spray on all the plant parts. After this, a gentle rinsing method by lukewarm water is followed. And, it’s done.

The Takeaway:

Using hot water on plants has been used for many years as a natural way to kill pests and diseases. Slightly hot water is very effective in killing pests. It kills the stubborn root mealybug even. Follow the ways mentioned above of watering plants with hot water. Those might help you as well as your plants a lot.  

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