Updated at: 08-11-2022 - By: Sienna Lewis

Have you ever heard of the practice of soaking your plants in hot water to expedite growth? When it comes to watering plants, is it even possible to use hot water safely?

Most plants can handle water temperatures up to 120°F (49°C). A plant’s cell and root structure can be damaged above that temperature. Root stress and withering can also occur when the water temperature drops below 40°F (5°C).

The appropriate water temperature for watering houseplants and the advantages and disadvantages of using hot water for plants will be discussed in this essay.

We are ready to go now.

Best Water Temperature for Plants

The amount of Dissolved Oxygen (DO) in your plants’ water is affected by the temperature of the water.

A plant’s root growth, nutrient absorption, and photosynthesis are all improved when oxygen is present as dissolved in the plant’s water.

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To put it another way, if your plants’ water has a high DO level, you can be sure that it’s good quality.

68-78°F (20-26°C) is generally considered the appropriate water temperature for plants. These ranges have dissolved oxygen concentrations more than 8 mg/l, making them ideal for healthy root development.

Water becomes hypoxic and severely hazardous to plants when the DO concentration drops below 4 mg/l when the temperature exceeds 122°F (50°C).

The benefit of High-Temperature Water on Plants

Plants can benefit from utilizing hot water, even if it isn’t optimal. Pest problems can be alleviated with the use of hot water.

Hot water baths and showers can be used to get rid of bug infestations.

Immerse your plant pot in a pail of hot water at 120°F for 1 – 10 minutes, depending on the size of the pot. Pests like aphids, scale, mealybugs, and mites can be eliminated with this strategy.

The root ball of your potted plants should not, under any circumstances, be warmer than 115°F.

You can use this method to keep your potted plants from suffering from heat damage by spraying them with 120°F boiling water for 5 minutes, followed by a 1-minute cold rinse. Three times is a magic number when it comes to this technique. To get rid of nymphs and crawlers, you can use this method.

Dangers of Using Boiling Water on Plants

Warm water is essential for plant growth, however boiling water above 120°F might be harmful to the plants.

The plant’s structure and root system can be damaged by boiling water, and if the leaves are touched, their protective coating will be melted. Additionally, it can eliminate germs from your potting mix that are essential for plant growth.

Damage plant structure

The turgidity and shape of plant cells are dependent on water. However, if you use boiling water to water your potted plants, the cells will be completely destroyed.

Flaccidity results from the cells’ inability to hold water.

Damage root system

It’s no secret that plants rely on their root systems for stability. In addition to providing critical nutrients for plant growth, it also adsorbs moisture from the soil.

The roots of your potted plants will be scalded if you use boiling water to water them, preventing them from absorbing water and nutrients.

Killing microorganisms needed for growth

Rhizobia, mycorrhizal fungi, actinomycetes and diazotrophic bacteria are likely to be present in your soil.

Nutrients and plant growth hormones cannot be produced without them, and they can also be used to fight off illnesses and parasites.

Using water that is hotter than 120 degrees Fahrenheit kills these bacteria, putting an end to the growth of your plants.

Damage leaves protective layers.

If you’re going to use hot water, aim it at the roots and stay away from the foliage. The cuticle of your leaves might be melted by hot water.

To keep viruses and pests out as well as stress from the environment out, plants have a cuticle covering their outermost leaves.

Plants are more vulnerable to disease when they lack this layer of defense.

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Signs Your Plants Could Not Tolerate Hot Water

When exposed to over-boiling water, most plants will show signs of discomfort, however this will vary on their unique tolerance.

There are some plants that are more vulnerable than others.. Using water that is too hot will cause your plant to droop and wilt, making it look like it’s going to die.

How Long Do Plants Need to Heal After Being Submerged in Hot Water?

Damage to the roots can be treated with hot water if it affects only a small area. A couple of days should be enough time for them to recuperate, as long as the soil isn’t too hot when you water them.

The root damage is so serious that there is little you can do to save it.

Root temperature

Roots can best absorb water and nutrients at 68 degrees Fahrenheit. During this time, the substrate water is still full of oxygen, and the temperature of the roots’ pump mechanism is just right. Plants are less able to take up oxygen from the water at higher temperatures because the pump mechanism is less efficient at lower temperatures. This can lead to an increase of hazardous molds (like Pythium) and bacteria, and all the related health issues that come with them.


So it’s critical to keep your substrate at the appropriate temperature. Watering will not change the substrate’s temperature, which is a bummer. A quarter of an hour after the watering, the temperature in the substrate would go back to where it was before the watering, thus you would need to use extremely hot or extremely cold water to do this.

Growth and Development

Plants’ metabolic activity slows down when the water temperature is too low. Wild rice plants cultivated in cool water had fewer and shorter leaves than plants produced in warmer water, according to a 2007 study published in “The Southwestern Naturalist.” Fertilization was similarly compromised in the cool-water plants.

Aquatic Plants

Aquatic plant growth is influenced directly by water temperature. The term “thermal pollution” refers to the entry of warm water into a body of water that isn’t in any way normal. These pollutants include runoff from hot highways and warm water discharged from industrial buildings. The population dynamics of aquatic plants are altered by thermal pollution, allowing formerly rare species to flourish in warmer temperatures. Aquatic plants that float to the top of heated water are another interesting fact.


There are a lot of tropical houseplants in the market. Providing your indoor plants with cold water may seem like a nice change, but it may really stress them out. Cold water squirting on leaves and flower buds can cause white spots to appear on the foliage and bud drop. Water additives that are damaging to plants will settle in warmer water, so let the cold water warm up to room temperature before watering.

Seeds and Vegetative Cuttings

The plant nursery and seed industry employs hot water to eradicate diseases and insect pests on cuttings and seeds. Bacteria can be killed by boiling the seeds of vegetables such as eggplant, tomato, carrot, and celery in hot water. Seeds from other species, on the other hand, are more susceptible to the heat. Squash and pumpkin seeds, according to researchers at Ohio State University, are harmed by hot water. In a 2005 study published in the “Journal of Economic Entomology,” researchers found that soaking grape cuttings in hot water can help control mealybugs.

What is Thermal Pollution?

The term “thermal pollution” describes when the temperature of an ocean, river, lake, pond, or other natural body of water changes dramatically. This condition is triggered by human intervention.

Any time a facility consumes natural resources and then recycles the recycled water, this phenomenon occurs. For the most part, these factories or industrial facilities use water to cool their machinery in order to improve their ability to produce superior products.

How Does Thermal Pollution Affect Aquatic Plants?

When the water temperature fluctuates, the growth of aquatic plants is dramatically affected. The population dynamics of aquatic plants change when abnormally warm water is introduced into a natural water body, such as during thermal pollution.

When industrial operations leak warm water from heated highways to streams, for example, plant species that normally populate a small region can become densely populated. Another example is when warm water is introduced into a natural body of water and certain plants rise to the surface.

How Does Cold Water Affect Houseplants?

Plants that thrive in tropical climates are commonly found in homes. For this reason, they stress whenever cold water is used to hydrate them. In fact, research reveal that splashing cold water on certain plants can cause white patches on their leaves and bud drop.

How Can Hot Water Be Beneficial to Seeds and Vegetable Cuttings?

The majority of houseplants originate in tropical areas. Because of this, they become agitated anytime cold water is used to rehydrate. According to research, splashing cold water on certain plants can cause white patches on the leaves and the decline in bud size.

Is it safe to use cold water for plants?

Even if your plants aren’t killed, water below 68°F (20°C) can put them into a dormant state. If they don’t produce new leaves or blooms, they’ll die.

This can cause root shock, causing long-term root damage, leaf drooping, and possibly plant death if the water temperature is below 40°F (5°C).

Do I need to heat rainwater for plants?

Some people worry that rainwater collection from the roof may collect toxins, however boiling rainwater is usually unneeded.

In order to limit the amount of impurities gathered, roof filtration systems are an option.

How Long Should You Boil Water For Plants?

Gardeners who are concerned about pollutants or impurities that could harm their plants will sometimes boil the water.

Most pollutants can be killed in water by bringing it to a rolling boil for one minute at 212°F.

In order to avoid killing the plants, the water must be cooled down to room temperature before being used.

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Watering During a Hot Day

Several folks contacted me to inquire about whether or not it is safe to water on a hot summer day. When it’s still cool outdoors, you can water your plants even on a hot day. However, this should be done early in the morning or late at night.

During hot weather, water will evaporate quickly from your plant if you water it in the middle of the day.

How to Reduce the Temperature of Your Garden Hose’s Water

The water in your garden hose can reach dangerously high temperatures during the summer and heatwaves. It’s scorching out there!

Before watering your plants, let the hose run for a few minutes. Use this to bring the temperature down to safe levels.

Final Thoughts: How Does Water Temperature Affect Plant Growth?

How does water temperature effect plant growth? Congratulations! Try your hand at greenhouse gardening if you’re looking for a new kind of gardening experience. You can focus on creating the best growing conditions for your plants when you have an enclosed place to protect them from pests and inclement weather