Soil pH measures alkalinity or acidity in the soil and is an important factor for a healthy, happy garden. It can affect the availability of essential soil nutrients needed for plant growth and development and the growth of microorganisms in the soil.

Different plant species require different pH levels, so understanding soil pH is key to ensuring your plants get what they need to thrive.

The ideal soil for most plants will range from slightly acidic (around 6.5) to slightly alkaline (around 7.5). Knowing how to adjust soil pH when necessary is an important part of maintaining a green and healthy garden that can encourage strong root formation and aid water absorption, which will effectively help keep your plants nourished.

There are ways you can manage and maintain fluctuations in soil pH, such as by amending it with organic matter like compost or lime applications, which will adjust the acidity level accordingly.

What’s The Importance of Soil PH in Gardening?

Soil pH is an important factor to consider when it comes to gardening. Soil pH affects the availability of nutrients, the growth and development of plants, and the health of soil microbes. An optimal soil pH range for most plants is between 6.0 and 7.0; some plants prefer slightly acidic or alkaline soils outside this range.

When a soil’s pH is at the right level, this can improve the amount of nutrients plants can absorb, leading to healthier plants with more vigorous growth.

If your soil’s pH is too high or low, you may need to amend the soil with organic matter like compost or lime. Testing for soil pH and adjusting it accordingly is a good practice for any gardener to follow to achieve optimal plant growth conditions.

What Determines Soil PH?

Soil pH is determined by a combination of factors, including the parent material from which it was formed and any changes in climate, farming practices, and vegetation it has been subjected to.

A soil’s natural pH level is often altered due to using fertilizers, mining, or even topography, which generally makes the soil more acidic.

This is especially the case in Australia, where most soils are acidic except for those found in most parts of South Australia or Western Australia which are typically alkaline.

The alkalinity or acidity in soil depends on how much calcium and magnesium are present, along with certain cations such as iron, aluminum oxide, sodium, and potassium. The pH scale ranges from 0 to 14, with a 7 indicating a neutral pH level, while values below 7 indicate acidic soil, and those above 7 represent an alkaline one.

For plants to absorb the nutrients they need, they must be grown in soil with a suitable balance between acidity and alkalinity. Different crops might require different acidity levels to grow best – this means that soils can be adjusted based on the particular crop being planted by adding compounds such as lime or sulfur in varying amounts.

How Does PH Affect Plants?

Soil pH is important when growing plants, as pH levels outside the ideal range can limit or even kill a plant. It is especially important to pay attention to soil pH levels since the amount of nutrients available to the plant in its root zone depends on it.

If a soil’s pH drops too low, below 6, it becomes too acidic for most plants, and some key nutrients become unavailable for uptake. On the other hand, if the soil pH rises above 8, phosphorus is suddenly bound up and unavailable regardless of how much fertilizer you add.

Aside from being unable to absorb vital nutrients from the soil, extreme acidity or alkalinity can stunt or even stop root growth, which will have a direct effect on this, limiting water and nutrient uptake from that same soil.

It is best to check your soil’s pH to avoid these dangerous issues with your plants. And if there are any problems, they should be addressed immediately with proper fertilizers or other remedies, such as adding lime to make the soil more alkaline if needed.

How Can I Improve PH?

Improving soil pH is an important part of successful gardening. Soil pH affects the availability of many essential nutrients that plants need to grow and thrive. If the soil pH is too low, certain nutrients may be unavailable to the plant, leading to nutrient deficiencies and poor growth.

On the other hand, if the soil pH is too high, certain nutrients can become toxic to plants. In those cases, you need to take some steps:

To Decrease PH

To make the soil more acidic, there are several ways to go about it. For example, using ammonium sulfate or ammonia nitrate is a quick solution as these fertilizers dissolve into the soil and reduce the overall pH level.

This can be an effective way of getting the desired results, but they take quite a while to wear off, so multiple applications may be needed depending on how acidic the soil needs to become. If too much fertilizer is used, it can lead to problems such as nutrient deficiencies in plants or create further alkalinity in the soil.

An alternative option that people use is sulfur due to its long-lasting effects. However, this could take some time as it requires multiple applications over months before showing significant effects. This method also requires caution while mixing into the soil as an excess amount of sulfur should not be used since this would have damaging consequences for both plants and their environment.

You can buy aluminum sulfate from most lawn and garden stores which provides a good deal of acidity for the required purpose; however, you must always stir it well with the soil before applying after measuring the correct amounts for best results.

Increase PH

Raising the soil’s pH level to increase its alkalinity can be done relatively easily with just a few simple steps. The first step is to add a form of lime to the soil, which will help neutralize acidity and increase the pH value.

Lime is usually obtained in three forms – ground agricultural lime, burnt lime, or hydrated lime (slated lime). All forms of lime are typically made up of some combination of calcium and/or magnesium, also commonly known as pure calcium carbonate.

Choosing the form that suits you best depends on your desired results or timeline. If you need results quickly, finely pelletized or hydrated lime will offer the quickest performance since it is more soluble in water and can permeate the soil quite quickly.

Alternatively, if you have time on your side, then using the slower-acting ground agricultural or burnt limestones may suffice and still reach similar levels when given enough time to work its way down into your soil through natural rainfall or irrigation.

Frequently Asked Questions [FAQs]

1. What Is Soil PH, And Why Is It Important In Gardening?

Soil pH measures the acidity or alkalinity of the soil, ranging from 0 to 14. In gardening, soil pH is crucial because it affects plant growth and nutrient availability. Different plants thrive in different pH levels, so understanding and managing soil pH can help plants grow healthy and strong.

2. How Do You Test The Soil PH In Your Garden? 

There are several ways to test soil pH in your garden. One common method is to use a soil pH meter, which measures the pH level directly. Another way is to use a soil test kit, which typically involves mixing a soil sample with a test solution to determine the pH level.

3. What PH Level Is Ideal For Most Garden Plants? 

Most garden plants prefer a slightly acidic to neutral soil pH, ranging from 6.0 to 7.0. However, some plants, such as blueberries, prefer a more acidic soil with a pH between 4.5 and 5.5, while others, such as asparagus, can tolerate a more alkaline soil with a pH of 7.0 to 8.0.

4. What Happens If The Soil PH Is Too High Or Too Low?

If the soil pH is too high (alkaline), some plant nutrients, such as iron, may become unavailable, leading to yellowing leaves and stunted growth. On the other hand, if the soil pH is too low (acidic), aluminum and manganese may become toxic to plants, leading to stunted growth and poor yields.

5. How Can You Adjust Soil PH In Your Garden? 

To adjust soil pH in your garden, you can add materials that either increase or decrease the pH level. For example, to lower the pH level, you can add sulfur, peat moss, or aluminum sulfate, while to raise the pH level, you can add lime, wood ash, or bone meal.

It’s important to follow recommended application rates and retest the soil pH after applying any amendments to ensure the pH level is within the desired range.


Soil pH is vital in gardening and should be properly monitored and adjusted when necessary. Testing the soil pH is the first step, followed by adding materials to raise or lower the pH level as needed. It’s important to follow recommended application rates and retest the soil pH after applying any amendments to ensure your plants’ pH level is within the desired range.

About the Author

Virginia E. Hayes is a gardening enthusiast who loves to write about gardening tools, safety issues, and ways to keep gardens clean and safe. With her vast experience in gardening, she provides valuable insights and tips to help fellow gardening enthusiasts to enhance their gardening experience. Her passion for gardening and writing has made her a sought-after author in the gardening community.

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