How To Adjust Water pH For Plants


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The pH level of water refers to its acidity or alkalinity, and different plants have different preferences. To adjust the water pH for plants, you can start by testing the pH level of your water source using a pH testing kit. If the pH level is too high or alkaline, you can lower it by adding organic matter such as compost or peat moss to the growing medium. On the other hand, if the pH level is too low or acidic, you can raise it by adding lime or wood ash to the soil. 

Looking to boost the health and growth of your plants? One crucial factor to consider is the pH level of the water you use. Maintaining the proper pH balance can make all the difference in the success of your plants. 

In this guide, we will explore the importance of water/growing medium pH for plants and provide you with essential tips on how to adjust it effectively. 

We will delve into the science behind pH and its impact on plant absorption of nutrients, as well as the signs of pH imbalance to watch out for. With our step-by-step instructions and practical advice, you’ll be equipped with the knowledge to create the perfect pH environment for your plants to thrive. Get ready to take your gardening skills to new heights!

The Importance Of pH For Plants

pH is a term that is often associated with chemistry, but did you know that pH is also incredibly important for plants?

pH stands for “potential of hydrogen” and refers to the measurement of the acidity or alkalinity of a substance. In the case of plants, pH plays a critical role in their overall health and well-being. The pH level of the growing medium in which plants are grown can significantly impact their ability to absorb nutrients and thrive. This makes it vital for gardeners and farmers to understand the importance of pH and how to manage it effectively.

When it comes to plants, pH levels can have a significant impact on their growth and development. Different plants have different pH preferences, with some thriving in acidic conditions while others prefer an alkaline growing medium. Understanding the ideal pH range for a specific plant is crucial for ensuring optimal growth. However, typically water used for soil irrigation (water) should have a pH level of between 5.0 and 7.0.

If the soil’s water pH is too high or too low, it can lead to nutrient deficiencies, stunted growth, and even plant death. This makes it essential for you to regularly test the pH of your irrigation water and soil and make any necessary adjustments to ensure that your plants are receiving the right balance of nutrients.

The pH level of the growing medium affects nutrient availability for plants. When the growing medium is too acidic or too alkaline, certain nutrients become locked up and are unavailable for plant uptake. This means that even if the growing medium contains an adequate amount of nutrients, plants may still struggle to absorb them if the pH is not within the optimal range. 

For example, iron deficiency is a common problem in plants growing in alkaline soils, as iron becomes less soluble and therefore less available to the plants. By maintaining a suitable pH level, gardeners can ensure that their plants have access to all the essential nutrients they need for healthy growth.

pH also plays a crucial role in the activity of beneficial microorganisms in the growing medium. Many beneficial bacteria and fungi that help break down organic matter and release nutrients for plants have specific pH preferences. If the pH of the growing medium is too far outside their preferred range, these microorganisms may become less active or even die off. This can harm the overall health of the soil and the plants growing in it. 

By maintaining an appropriate pH level, gardeners can create a favorable environment for beneficial microorganisms to thrive and support plant growth.

How To Increase pH In Water For Plants?

Most plants prefer a slightly acidic to neutral pH level, which is around 6 to 7. However, there are instances when you may need to increase the pH of your water to accommodate the specific needs of certain plants. Luckily, there are several methods you can employ to achieve this.

Baking Soda

One simple way to increase the pH in water for plants is by using baking soda. Baking soda, also known as sodium bicarbonate, is a readily available household item that can be used to raise the pH level in your water.

  • To use baking soda, you can mix one teaspoon of it into a gallon of water and stir until it dissolves completely. 
  • Make sure to test the pH level of your water before and after adding the baking soda to ensure you achieve the desired increase in pH. 
  • Be cautious not to use too much baking soda as it can raise the pH too high and harm your plants.


Another method to increase the pH in water for plants is by using lime or limestone. Lime contains calcium carbonate, which can help neutralize acidic water and raise its pH level. You can find lime or limestone at your local gardening store or home improvement center.

  • To use lime, simply dissolve a small amount in water according to the package instructions and add it to your watering can or irrigation system. 
  • Remember to test the pH level after adding the lime and adjust accordingly.

Crushed Eggshells

If you prefer a natural method, you can also use crushed eggshells to increase the pH in water for plants. Eggshells contain calcium carbonate, which acts as a natural buffer and can help raise the pH level.

  • To use eggshells, collect and rinse them thoroughly to remove any residue. 
  • Allow them to dry completely before crushing them into small pieces. 
  • Add the crushed eggshells to a container of water and let it sit overnight. The water will absorb the calcium carbonate from the eggshells, increasing its pH level. 
  • Strain the water before using it to water your plants.

Wood Ash

Lastly, if you have access to wood ash, it can be an effective way to increase the pH in water for plants. Wood ash is highly alkaline due to its high content of potassium carbonate.

  • To use wood ash, collect the ashes from your fireplace or wood-burning stove and mix them with water. 
  • Stir the mixture well and allow it to settle for a few hours. 
  • The resulting solution can then be added to your watering can or irrigation system. 
  • Be cautious not to use too much wood ash, as it can easily raise the pH level too high.

How To Decrease pH In Water For Plants?

If the pH level is too high, it can make it difficult for plants to absorb essential nutrients, leading to stunted growth and yellowing leaves. Fortunately, there are several methods you can use to decrease the pH in water for plants and create an optimal environment for their well-being.

Organic Acids

One effective way to lower the pH in water is by using organic acids. Some organic acids, such as citric acid, acetic acid, or phosphoric acid, can be added in small amounts to water to decrease its pH level. These acids are readily available in garden centers or can even be found in your kitchen pantry. It is important to use caution when handling these acids, as they can be corrosive. Always follow the instructions provided and wear protective gear, such as gloves and goggles, to ensure your safety.

Peat Moss

Another method to decrease the pH in water for plants is by using peat moss. Peat moss is known for its ability to lower the pH level of water due to its acidic nature. 

  • To use peat moss, simply place it in a mesh bag or nylon stocking and submerge it in the water you wish to lower the pH of. 
  • Allow it to soak for a few hours or overnight, and then remove the peat moss. 
  • The water should now have a lower pH level suitable for your plants.

Keep in mind that this method may not provide instant results, so be patient and monitor the pH level regularly.


If you have access to rainwater, it can also be an excellent option for decreasing the pH of water for your plants. Rainwater has a naturally lower pH due to its exposure to atmospheric carbon dioxide. Collecting rainwater and using it to water your plants can help maintain a more acidic environment. However, keep in mind that rainwater may not always be available or practical, especially during dry seasons or in areas with limited rainfall, so always have a backup solution, should you need it!


Using sulfur is another effective way to decrease the pH in water for plants. Sulfur reacts with water to form sulfuric acid, which lowers the pH level. You can find sulfur products, such as sulfur powder or pellets, at garden centers. Follow the instructions provided on the package for the appropriate amount to use based on the volume of water you need to treat. 

It is important to note that sulfur can take some time to dissolve and react with water, so be patient and allow it to mix thoroughly before testing the pH level.

How To Measure Water pH For Plants?

As a gardener or plant enthusiast you need to know how to measure water pH for plants accurately. In this step-by-step guide, we will walk you through the process of measuring water pH for plants.

Step 1: Gather the necessary equipment

To measure water pH, you will need a pH testing kit or a pH meter/sensor. The kit typically includes pH test strips or a liquid reagent, while the meter is a digital device that provides more accurate readings – our recommended approach! 

Additionally, you will need clean containers to hold the water samples and distilled or deionized water for calibration if using a pH meter.

Step 2: Collect the water samples

Collect water samples from different sources in your garden or home. It’s important to test the water that you are using for watering your plants as well as any other water sources that might come into contact with your plants, such as rainwater or tap water.

Step 3: Prepare the water samples

Take clean containers and fill them with the collected water samples. Make sure the containers are clean and free from any residues that could affect the accuracy of the pH measurement.

Step 4: Test the water samples

If using a pH testing kit, dip a pH test strip into the water sample and compare the color change against the provided color chart to determine the pH level. 

If using a liquid reagent, follow the instructions on the kit to add a few drops of the reagent into the water sample and observe any color changes.

If using a pH meter, calibrate the device according to the manufacturer’s instructions using distilled or deionized water. Once calibrated, immerse the electrode of the meter into the water sample and wait for the pH reading to stabilize. Take note of the pH reading displayed on the meter.

Step 5: Interpret the results

Compare the pH reading obtained from the water samples to the ideal pH range for your specific plants. If the pH level is within the desired range, then the water is suitable for your plants. However, if the pH level is too high or too low, you will need to take the corrective measures listed above to adjust the pH of the water before using it for watering your plants.

By following this step-by-step guide, you can easily measure water pH for plants and ensure that you are providing them with the ideal growing conditions. Remember, regular monitoring of water pH is important as it can change over time due to various factors such as soil composition and fertilizer use.


Whether you have a thriving garden or a collection of indoor plants, understanding the role of pH in plant nutrition is essential to ensure optimal growth and vibrant foliage. 

Adjusting the pH of the water we use can help create the ideal environment for our plants to grow and flourish. It’s important to note that when adjusting the pH of plant water, it’s best to do so gradually. Sudden and extreme changes in pH can shock and harm plants.

If you have any questions regarding plant pH or what pH meter will best suit your gardening needs, do not hesitate to contact the world-class team at Atlas Scientific

pH Probes & Sensors

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