Water pH for growing plants: 10 signs it’s too high & too low

It is widely accepted in the botanical world that the 5.5 – 6.5 pH range is the most ideal for growing plants. You will also have healthy plants and a beautiful garden when you have the right soil pH. Too many gardeners overlook this important aspect, which is why some people get better crop results than others.

While an incorrect pH will not kill your plants, it will severely affect their growth, and the results will be unsatisfactory. The plant will not be able to develop fully if it doesn’t have the ideal environment. If you are curious about the water pH for growing plants, continue reading as we talk about 10 signs of too high & too low pH. 

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Table of Contents

Why is pH important in plant water?

The water you use for the plants directly influences the soil pH. All the nutrients and chemicals that can dissolve in the water depending on the soil itself. Depending on the plants you are growing, you might want to lower or increase the pH levels of the water.

While some species find more nutrients in acid conditions, others prefer alkaline ones. Do your research based on the plants in the garden and figure out the ideal conditions for them. But even if you skip this step, you should know that most nutrients are available in neutral water with the standard pH7.

However, extreme levels are not recommended. If the soil pH level is below 5.5, your plants will struggle a lot. Additionally, alkaline soils will encounter problems with high sodium levels as the levels go above 9. 

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How does water pH affect plant growth?

While it has an effect on humans, water with different pH levels has the same one on plants. If the water’s pH is too low, it can cause several problems in the plant’s growth. The root will not be able to develop if the soil is fully too acidic, and in this case, you will have to increase the levels of the soil.

Minerals like iron will clog your irrigation equipment if there is an improper pH level in the water. Your plants will need specific nutrients to thrive in their environment, and the levels directly influence whether they can assimilate these nutrients or not. It is recommended to keep the pH of your plant’s water between 5.5 and 6.5 for the best results. 

Signs of high pH in plants

When the levels are too high, your plant will let you know by displaying a couple of symptoms. When you notice them, it is a good indication that you have to lower these levels and take the necessary action. If the soil is too alkaline, your plants might suffer from several potential issues.

Nutrient deficiency is a big problem in pots that feature a high pH. Minerals like calcium and iron are necessary for your plants, but they cannot assimilate them in this environment. An easy way to determine if your plants are struggling with a high pH is to identify the following symptoms:

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  • spots of leaf necrosis
  • brown spots on leaves
  • interveinal leaf chlorosis
  • dark green leaves that have red or purple spots on them
  • wilted leaves

If you notice any of the symptoms mentioned above, you should measure the levels with a tool. Make sure the levels are not too high. If they are, lower them down to the 5.5 – 6.5 range. 

Signs of low pH in plants

Low pH levels bring problems as they make the soil too acidic. While most plants can live healthy in an acidic environment, some will find these levels too low. In the long term, the levels of your soil will naturally fluctuate. It is another reason why you should constantly monitor and regulate this factor.

Some nutrients are available even if the soil is highly acidic. Still, others are completely out of reach for your plants. An ideal level should be achieved for your crops to assimilate all the minerals and nutrients successfully.

When that doesn’t happen, your plants will display several symptoms. Once you notice them, increasing these levels as soon as possible is recommended. They are:

  • leaf tip burn
  • leaf chlorosis
  • withered or twisted leaves
  • brown spots on leaves
  • dark green leaves featuring red or purple spots
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Best pH balancers for plants

There are many ways to stabilize the pH levels of your plants. While not all of them are highly effective, there is a specific product that will help you achieve ideal results quickly. We found it after searching the market for the best gardening solutions.

General Hydroponics pH Up and Down Liquids

This bundle includes two different liquids. One of them is an acid that you will use to decrease the soil’s pH levels. The other one is a base, and it can be used to increase the pH. By using them alternatively, you can reach a balance in your plant’s pot. 

You can stabilize the soil with these liquids as they help regulate the environment. The solution contains potassium hydroxide and potassium carbonate, which are known to be effective for this purpose. The pH-down solution contains phosphoric acid, the best solution for lowering levels. 

NameGeneral Hydroponics pH Up and pH Down Liquids
Country of OriginUSA
Item Weight6 pounds
ManufacturerHawthorne Hydroponics, LLC
Product Dimensions7 x 7 x 9 inches


  • Great value purchase
  • It’s very concentrated, so you’ll want to be careful when using it.
  • It can restore life for your plants.
  • You’ll have plenty of the product.


  • You need a pH meter to make sure you end up where you want.
  • We tried getting in contact with customer support, but it was pretty hard.
General Hydroponics
40,749 Reviews
General Hydroponics
General Hydroponics ensure the best conditions for your green friends.

pH water level chart

We find a wide range of pH levels in nature and our society. From battery acid to ammonia, these levels change a lot. If you wondered what effect they have on the environment, we included the ones regarding aquatic life. Look at this chart, where you can see common examples of different levels and their influence on the environment. 

Environmental effectsExamplespH value
Battery acid0
Sulfuric acid1
Lemon juice2
Orange juice3
All fish dieAcid rain
Acidic lake
Frog eggs, tadpoles, crayfish and mayflies dieBananas
Clean rain
Rainbow trout begin to dieHealthy lake
Pure water7
Sea water8
Baking soda9
Milk of Magnesia10
Soapy water12
Liquid drain cleaner14

Pros & cons of acidic water for plants

Many gardeners prefer acidic water over alkaline one when they regulate the soil of their crops. By nature, plants favor acidic water over alkaline one to facilitate better growth. The ideal range should be between 6 and 7; your plants can absorb the nutrients easily.

But there are both good and bad things about acidic water. Let’s take a look at some of them.

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  • It helps the germination process
  • It helps the plants with blooming and revives the damaged ones
  • Ideal for seeds and plants in their first stages of life
  • Promotes sprouting of vegetables
  • Easier to get dissolved by plants


  • It can hurt the plant if there are too many minerals
  • Some species thrive better in alkaline environments
  • The growth of the root might be negatively affected

How to lower the pH in the water for plants

If the pH levels are too high, you can lower them yourself. You can use many methods for the well-being of your crops. We recommend that you purchase the product presented above, which contains solutions for regulating levels. 

But you can also try to add lime or wood ash, as they are known for lowering the pH of the soil. As you add these solid materials to the liquid solution, it can soak the water over time and regulate the soil in the pot. If you have access to these chemicals, you can also use sulfur or phosphoric acid if you want faster and better results.

You can test the pH regularly and make sure the ideal range is always met. This level can change over time, a normal and natural effect. That is why you must constantly balance the soil if you want exceptional crop results. 

How to fix hard water for plants

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If the water is too hard, you can soften it by following some easy methods. Expert gardeners recommend them, so you don’t need to test them first. We recommend the most effective natural ways to fix your plants’ hard water.

  1. Leave the water to sit for 24 hours.

It is one of the easiest ways to soften the water before you use it for your plants. Let it sit for at least 24 hours, and you will notice the effects the next day. Because it is exposed to the air and the temperature from outside, the components will dissolve naturally, and the salt content will be trapped at the bottom.

  1. Use volcanic rocks

If you have them available, volcanic rocks are also an ideal solution. They are highly porous and allow water to flow through them. These rocks do a great job retaining magnesium and calcium carbonate, which can be found in hard water

  1. Boil the water

If you want the benefits of the first method but are against the clock, boiling water will get you the same results quicker. When heated to high temperatures, the harmful additives will be removed from the water. Make sure to cool the liquid down before you apply it to your plants. 

the pH of miracle gro potting soil

All gardeners are familiar with this popular product which is potting soil that contains the necessary nutrients for your crops. The pH of this soil ranges between 5.5 and 6.2, which is considered ideal for most plants. 

Miracle-Gro Indoor Potting Mix

The botanical experts at Miracle-Gro worked together to create this excellent potting mix. It is a blend intended for a wide variety of plants and is estimated to last you for at least half a year. Because it has no compost added, there is a low risk of fungus gnats.

You can grow container plants with this mix, which has a formula that makes it easier for you to water the plants. Don’t forget to ensure proper drainage for the pots, and make sure to repot your plants every year while using this potting mix. 

NameMiracle-Gro Indoor Potting Mix
Country of OriginUSA
International ShippingThis item is not eligible for international shipping.
Item Weight12.52 pounds
ManufacturerThe Scotts Company LLC
Product Dimensions21 x 12.75 x 3.88 inches


  • It’s the best potting soil out there.
  • It gives plants a great start to life.
  • We’ve always been happy with the quality of this stuff.
  • It drains the right amount.


  • It’s on the more expensive side.
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Miracle-Gro Indoor Potting Mix
Miracle-Gro indoor potting mix Is great.

Water pH level for seedlings

When you have the seeds of your favorite plant, you must be careful with them and create ideal conditions to facilitate their growth. Be advised that the pH levels should be between 6 and 6.5 if you want the best results.

If this level is too low, your seeds will find it toxic, and the plant will not grow in this harsh environment. Additionally, an excessive pH will bring other problems that will make it difficult for your favorite crop to thrive and stay healthy. 

If you can, test the minerals in the water before you apply them to your seedlings. Make sure there are low levels of sodium as well. Most soft mineral waters already feature a reduced sodium level, so you should consider them for your new pots. 

How to keep pH stable in hydroponics

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You can regulate the pH levels in hydroponics by using specific products intended for this purpose. While you can find them in liquid form, some brands will also sell them in dry form so that you can choose the one suited for your pots. 

You should always make sure that they are formulated specifically for hydroponics systems. Regular ones will not be effective, and you will have to look for products created by professional brands. Additionally, you can add vinegar or citric acid to the solution to decrease the pH levels faster.

Remember that the first step in keeping a stable level is testing. You should always check all of your pots every week and note down the measurements. Keeping track of these natural changes will allow you to prepare in advance and take quick action in regulating the environment. 

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Is 9.5 pH water good for plants?

All gardeners would be frightened by a 9.5 pH water level. When it is too alkaline, several problems will occur in your plants. The ideal level for your crops is between 5.5 and 6.5, so you should regulate the soil to reach this range. 

Does the pH level of water affect plant growth?

The pH levels of the water you use for your plants have been found to affect their growth directly. If it is too low, it can cause problems in the root, which is the foundation of every plant. In nature, plants are used with acidic levels, so you should aim for their ideal range. 

What happens when the soil pH is too high?

Your plant’s growth will be severely restricted if the soil pH is too high. Several health problems will also occur, and you will notice brown spots on your leaves. It is also a sign of overwatering, so you might have to reduce how frequently you water them. 

How long does pH down take to work?

The solutions intended for regulating pH levels contain special formulas that allow immediate activation within the soil. However, you should wait between two to four hours before you start seeing results with your pH tester. Usually, smaller changes in the pH levels will happen faster than significant modifications applied to the soil. 

Patience is important in the gardening world. Whether we grow cucumbers or roses, we wait for months and years for our plants to grow and blossom. Allow enough time for the pH levels to stabilize before proceeding with other operations.