How Do You Test The Ph Of Potting Soil? (Landscape Advice)

Are you looking to optimize your garden’s growth by testing the pH of your potting soil? In this informative blog post, we offer landscape advice on how to accurately test the pH of your potting soil and make necessary adjustments for optimal plant health.

Learn about the importance of pH balance and discover techniques to maintain an ideal growing environment for your plants. Moreover, explore related subjects like reusing garden soil and choosing the right potting mix.

Enhance your gardening knowledge and ensure a thriving garden by mastering the art of soil pH testing—dive in and learn more now!

Understanding soil pH is important for optimal plant growth.
Most plants prefer a slightly acidic soil pH between 6.0 and 7.0.
Testing soil pH can be done using various methods, including DIY solutions or pH testing kits.
Adjusting soil pH can be done by adding specific soil amendments, such as lime or sulfur.
It’s important to research the specific pH preferences of the plants you want to grow.

Use a pH Test Kit

pH test kits are available at garden centers and home improvement stores for about $9 to $12.

They’re easy to use and inexpensive, usually costing less than $10. They can be used to test water as well if you need to know the pH of your water source before adding fertilizer or other chemicals into it.

The kit has several different strips that are designed for specific soils types (such as potting soil), so make sure you get the right kind of strip when purchasing one of these kits. 

You also want to pay attention to how accurate each strip claims to be (some claim +/- 0.5 numbers, while others claim +/- 1 number).

Collect a Sample of Soil

You can test the pH of potting soil by collecting a sample of soil. To do this, use a clean spoon or trowel and dig into the top 3 inches of potting soil. 

Avoid taking samples from around plants or trees because those areas are likely to be more acidic than the rest of your potting soil. 

Collect only what you need for testing purposes; if you have more than one plant you want tested, take separate samples from each plant so that they can be treated as separate entities in their own right (i.e., don’t mix them together).

“The pH of your potting soil can greatly impact the health and growth of your plants. If you’re using Vigoro All-Purpose Potting Mix, check out our article on its pH level and how it affects your plants.” – What is the pH of Vigoro All-Purpose Potting Mix?

Add Distilled Water and Stir

Now that you’ve got the water’s pH in mind, let’s go ahead and add some distilled water to your soil. 

Distilled water is pure and contains no minerals, so it will not change the pH of your potting soil. Keep in mind that the soil you’re testing is a complex mixture of minerals that were naturally present in its original form (say, dirt). The addition of distilled water will not change the pH of that soil.

Fill Soil Test Tube With the Soil Solution

Now, you need to fill your test tube with the soil solution. To do this, use a small pipette or dropper and carefully transfer the soil solution into the test tube until it reaches the line on the side of the tube. 

Be sure not to overfill! You only want enough liquid in there so that you can see if your sample is acidic or alkaline by looking at how it reacts with a base indicator.

“Are you curious if potting soil is considered organic matter? Find out more about the composition of potting soil and its organic content in our informative article.” – Is Potting Soil Considered Organic Matter?

Add Indicator and Shake the Tube

Add about a dozen drops of pH testing solution to your sample. You’ll see the liquid change color; if it’s pink or red, your soil is alkaline (with a pH above 7). 

If it’s purple or blue, your soil is acidic (with a pH below 6). Shake the glass vial vigorously for five minutes until you are sure that the color change is complete.

Observe Color Changes

There are several ways you can test the pH of your potting soil. The easiest is with a pH meter, but those are expensive and not always available. 

If you don’t have one, or if the reading isn’t reliable for some reason (maybe the meter has been exposed to temperature fluctuations or was dropped), then there are other methods that will work in most cases. First off, let’s talk about color changes that happen when testing your soil.

  • Red: This is an indicator of high alkaline (high pH), between 4.5 and 6.5 on the scale 0-14 where 7 is neutral;
  • Yellow/Green: This indicates low alkaline (low pH), between 6 and 7;
  • Blue: This means that there is too much acidity in your potting soil (and therefore too much hydrogen ions) which makes it corrosive—a reading below 7 would be considered dangerous!

“How can you tell if your potting soil has gone bad? Our article provides helpful tips and insights on how to recognize the signs of bad potting soil and what you can do to prevent it.” – How Do You Know If Potting Soil is Bad? Answered

Check Your Chart

The pH number you get from your soil test will correspond to a pH value. Most plants grow best in soil that has a slightly acidic to neutral pH of 6.0-7.0, with 7 being neutral and below 6 being more acidic. 

You can use the chart above to determine whether or not your potting soil is within the ideal range for growing most common houseplants and flowers.

If your potting soil falls outside of this range, there are still things you can do to make it suitable for use with certain plant types (see “Soil Chemistry”). 

However if you’re trying to figure out what kind of plants would be best suited for your home garden, it’s important first consider how much space you have available as well as how much sunlight they’ll receive each day–these factors will play into their ability thrive outdoors!

Do Not Over-interpret the Test Results

You should never rely on a single test result to determine how much lime or sulfur to add. There are many factors that can affect the results of an individual test, including:

  • Soil type and texture
  • The amount of organic matter in your soil
  • The temperature at which the soil was sampled (the ph can rise as the day warms up)

As a general rule, you should expect to repeat this testing process at least twice, once after adding lime or sulfur and once again after all of your plants have been planted. 

If both tests agree within one small unit (0-0.5), then you are likely fine; if they do not, then try repeating the test again before making any adjustments.

“Bugs in potting soil can harm your plants and cause major headaches for gardeners. Learn how to make sure your potting soil is bug-free with our easy-to-follow guide.” – How Do I Make Sure There Are No Bugs in Potting Soil?

Correct pH Problems Before Planting

Soil pH is a key factor in plant growth and it should be tested before planting. If you’re not sure if your soil is acidic or alkaline, it will help to look at the color of your plant leaves. 

Blue-green, yellow and orange colors are signs that your plants might be suffering from an acidic environment. Purple and red colors mean that your plants could be experiencing too much alkalinity in their soil.

If you find yourself with an acid-loving plant growing in an alkaline environment, consider adding lime to increase its alkalinity in order to prevent further damage from occurring (it’s also recommended to add sulfur when adjusting for low pH levels).

Snail Shells Can Be Used to Raise Sodium Levels in Soil

If you have a soil that is too acidic, then you could add snail shells or eggshells to change the soil’s pH level. Snails are known for their calcium content and can be used as a way to increase the calcium content of your potting soil. 

Egg shells also provide calcium, but they can only be used when it comes to increasing sodium levels in soil as opposed to increasing pH levels (snail shells can do both).

Ashes Will Lower Soil pH

The pH of soil can be tested by taking a sample, adding water to it and then testing the solution with a pH test strip. If you need to lower the pH of your potting soil, you can add ashes from your fireplace.

Lime Will Raise Soil pH

Lime is a good way to raise soil pH because it’s a natural soil amendment. If you’ve got lime on hand, you can use it to increase the soil pH of your potting mix by sprinkling it over the top of your potting mix. 

You can also add lime to lower the pH if needed; however, this method is more difficult than using phosphoric acid or sulfuric acid solutions because it takes longer for limes effects to be seen in soil.

If you have high levels of nitrogen in your potting mix and want to keep them that way while increasing/decreasing pH levels as well as maintaining them at a specific level, try mixing some dolomite into your existing blend of peat moss and vermiculite (or other materials).

“Good potting soil is essential for the health and success of your vegetable garden. Check out our guide for tips on how to make your own high-quality potting soil for your vegetables.” – How Do You Make Good Potting Soil for Vegetables?


In conclusion, there are many ways to test the pH of your potting soil. You can use a pH test kit, collect a sample of soil and then add distilled water to create a solution from which you can observe color changes.

Further Reading

If you’re interested in learning more about soil testing and pH levels, check out these helpful resources:

How to Test Soil Acidity/Alkalinity Without a Test Kit: This article from The Spruce provides tips on how to test your soil’s pH level using simple household items.

Do It Yourself Soil pH Test: This article from The Spruce offers a step-by-step guide to testing your soil’s pH level at home.


What is soil pH?

Soil pH is a measure of the acidity or alkalinity of your soil. It is determined by the concentration of hydrogen ions present in the soil.

Why is soil pH important?

Soil pH is important because it affects the availability of nutrients to plants. Different plants have different pH preferences, so it’s important to know the pH level of your soil to ensure the best growing conditions for your plants.

What is the ideal pH level for most plants?

Most plants prefer a slightly acidic soil pH between 6.0 and 7.0. However, some plants have specific pH preferences, so it’s important to research the specific needs of the plants you want to grow.

How can I test my soil’s pH level at home?

There are several methods for testing your soil’s pH level at home, including using a pH testing kit, creating your own DIY testing solution, or using simple household items like vinegar and baking soda.

How can I adjust my soil’s pH level?

If your soil’s pH level is too high or too low, you can adjust it by adding soil amendments like lime to raise the pH level or sulfur to lower it. It’s important to follow specific instructions and guidelines for the amendments you choose to use.