How To Know If Soil Is Acidic (Here’s How!)

How To Know If Soil Is Acidic
How To Know If Soil Is Acidic (Here’s how!) –

Every plant has its preferred range of soil acidity. And any alteration in it can alter the plant’s growth as well. Acidic soils have a pH below 7.0, whereas the pH of alkaline soils is above 7.0. If you want to plant any plants that grow in acidic soils, you need to make your soil acidic. But how to know if the soil is acidic?

Here are the most common ways to know if the soil is acidic:

  • The pantry pH test for soil acidity or alkalinity
  • Red Cabbage water pH test
  • Test soil pH with a test kit

Generally, soil acidity means the soil pH is lower than less than 7, neutral pH, according to North Dakota State University.

So, we need to know how we can check the soil’s acidity. But before we discuss that, we need to know what characteristics the acidic soil has.

Characteristics of Acidic Soil

Soil pH or soil reaction measured in pH units indicates the acidity or alkalinity of the soil. The pH scale ranges from 0 to 14, with pH seven as the neutral point.

With a pH varying from 0 to 7, the soil is more acidic, and with a pH between seven to 14, the soil is increasingly more alkaline or basic.

Soil Nature pH Value
Extremely acidLess than 4.5
Very strongly acid4.5 to 5.0
Strongly acid 5.1 to 5.5
Moderately acid5.6 to 6.0
Slightly acid6.1 to 6.5
Neutral6.6 to 7.3
Slightly alkaline7.4 to 7.8
Moderately alkaline7.9 to 8.4
Strongly alkaline8.5 to 9.0
Very strongly alkalineMore than 9.1
How To Know If Soil Is Acidic (Here’s how!) –

The acidic soil has the following characteristics:

  • Soil acidity regulates the health of the plants in your lawn or garden.
  • Moderate soil acidity keeps the health and growth of some plants good, whereas higher soil acidity can also sustain life for some plants.
  • You might even want to know what happens when soil is acidic. The slightly acidic soils have advantages over highly acidic soils. Nutrients and minerals dissolve more easily in slightly acidic soils, and thus, the slightly acidic soils make nutrient availability to the plants easy.
  • On the other hand, highly acidic soils may destroy plant growth (not to mention that some plants prefer highly acidic soils).

What Makes Soil More Acidic?

  • Rainwater will leach away basic ions (calcium, magnesium, potassium, and sodium)
  • Carbon dioxide from decaying organic matter and root respiration dissolve in soil water, creating a weak organic acid.
  • Development of solid organic and inorganic acids, including nitric and sulfuric acid, from decomposing organic matter and oxidation of ammonium and sulfur fertilizers
  • In general, you can add lime to acid soils to increase soil pH, replace hydrogen ions, and help eliminate the most significant problems associated with acid soils. In addition, lime provides two nutrients, calcium and magnesium, to the soil.
  • According to Iowa State University, you can also lower the pH of small beds or garden areas by adding sphagnum peat, which is also an excellent source of organic matter.
    • If you have small garden plots, you can add a one to two-inch ( 5.08 cm) layer of sphagnum peat and work up to the top 8 to 12 inches (20.32 to 30.48 cm) of the soil before planting. Adding sphagnum peat to a large growing space can be expensive. It would be cost-prohibitive.

What Happens When Soil is Acidic?

The soil pH can affect plant growth by affecting beneficial microorganisms. In other words, bacteria that decompose soil organic matter are hindered in strong acid soils preventing organic matter from breaking down, leading to an accumulation of organic matter and the tie-up of nutrients, particularly nitrogen, contained in the organic matter.

For that, you need to know what type of plants you are going to plant (or have planted) in your garden. However, in most cases, plants best survive in slightly acidic soils. You can perform the following simple soil tests without the help of an expert.

How To Know If Soil Is Acidic

There are different ways of checking your soil properties, and the most accurate method of determining soil pH is by a pH meter, according to the State University of New York.
In addition, you can also use some indicators or dyes.

Plants, including azaleas, rhododendrons, and blueberries, tolerate strong acid soils and grow well.

See also: What Happens When You Leave Rhododendrons In The Sun Or The Shade?

1- The Pantry pH Test for Soil Acidity or Alkalinity

Follow the instructions below to perform the test:

  • Put two tablespoons of soil in a container.
  • Add a half cup of vinegar to the mixture.

Result: If the mixture fizzes, your soil is alkaline.

  • Put two tablespoons of soil in a container.
  • Moisten the soil with distilled water.
  • Add a half cup of baking soda.

Result: Add a half-cup of baking soda. If the mixture fizzes, your soil is acidic.

An important point to note: If your soil doesn’t react to any of the tests mentioned above, that would mean that your soil has a neutral pH.

2- Red Cabbage Water pH Test

Follow the instructions written below to perform your test:

  • Take a saucepan and measure two cups of distilled water into it.
  • Take a red cabbage and cut up 4-6 red cabbage leaves, and then add into the saucepan.
  • Simmer it for 10 minutes.
  • Remove the saucepan from the heat.
  • Now, allow it to set up for 30 minutes.
  • A liquid of purple or blue color will be formed. Strain it off. This liquid will have a neutral pH of 7.
  • Now, take a jar and add two teaspoons of your garden soil to it.
  • Add a few inches of cabbage water into the jar.
  • Stir the jar, and wait for 30 minutes.
  • Now, check the color.

Result: If the color turns sea blur or yellow-green, your soil is alkaline. If it turns pink/reddish, your soil is acidic.

3- Test Soil pH with a Test Kit

Apart from the DIY ways that make how to know if the soil is acidic easy, you can also use a test kit to check your soil’s pH. The order of operations can vary for different test kits, but the process typically involves the following steps:

  • In your lawn, dig a two to four inches deep hole.
  • There’ll be twigs and stones in the hole; move them away. 
  • Fill the hole with distilled water (Distilled water is water with a neutral pH value. If you don’t have it, you can buy it easily from your nearby grocery store).
  • Now insert the test probe once your created hole turns into a muddy pool.
  • Now, wait for some time. It will generally take about 1 minute to get a reading.

Result: If the reading is lower than 7, it means your lawn has acidic soil. If it’s higher than 7, your lawn has alkaline soil. The exact value of 7 will indicate that your soil is neutral.

How To Make The Soil Acidic Naturally

It can be challenging to make soil acidic since most of the time water is alkaline. However, the following organic ways will help you out in making your soil more acidic.

  1. Use well-decomposed compost each season to improve the soil acidity. Compost is organic and it improves the structure of the soil. Moreover, it also adds beneficial microorganisms into the soil.
  2. If you water your plants with compost tea, your soil will become more acidic.
  3. Apply organic, elemental garden sulfur to make your soil more acidic, as sulfur is an essential nutrient of plants.
  4. The use of organic mulch in your garden beds will increase your soil acidity as well.
  5. If you save coffee grounds and sprinkle them around your garden, it will increase the acidity of the soil.

See also: Is Sulfur Actually Good For The Garden? What Are The Pros & Cons Of Using It?

Plants That Thrive In Acidic Soil

Here are a few plants that grow well in acidic soil.

Plants That Thrive Acidic Soil pH requirements
BroccoliBetween pH 6.0 to 7.0
BlueberriesBetween pH 4.5 to 5.5
BeansBetween pH 6.0 to 7.0
BeetsBetween pH 6.5 to 8.0
Bok choyBetween pH 6.5 to 7.0
GarlicBetween pH 6.0 to 7.5
KaleBetween pH 5.5 to 6.5
PeasBetween pH 6.0 to 7.5
OnionsBetween pH 6.0 to 7.0
PotatoesBetween pH 4.8 to 6.0
SpinachBetween pH 6.0 to 7.5
ParsleyBetween pH 6.0 to 7.0
Lettuce and other leafy greensBetween pH 6.0 to 7.0
How To Know If Soil Is Acidic (Here’s how!) –

Before adding these plants to your garden, ensure you do your research because some may thrive in acidic conditions while others may hardly tolerate them.

Final Thoughts

Even though a pH meter is the most accurate way to know if the soil is acidic, there are also DIY methods to gauge your garden soil ph. 

Here are the most common ones: 

  • The Pantry pH Test for Soil Acidity or Alkalinity
  • Red Cabbage Water pH Test
  • Test Soil pH with a Test Kit.


Hello friends, I am Altiné. I am SO excited you are here! I am the guy behind Plants Heaven is a blog that shares information about preparing, creating, and maintaining gardens in and out of your home, regardless of where you live. My goal is to help you learn to love gardening and reap the benefits that come with it. I am still learning; therefore, the information I share on this site may not always be “expert” advice or information. But, I do my VERY best to make sure the information shared on this blog is both accurate and helpful.

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Every plant has its preferred range of soil acidity. And, any alteration in it can alter the plant’s growth as well. Acidic soils have a pH below 7.0, whereas the pH of alkaline soils is above 7.0. If you want to plant any plants that grow in acidic soils, you need to make your soil acidic. But how to know if soil is acidic?