Acidic Soil: Amendments For The Plants

Al Ardh Alkhadra > Blog > Gardening > Acidic Soil: Amendments For The Plants

acidic soil

Are your plants dying often? It is time to check your soil’s pH levels. Some plants can thrive in acidic soil while most prefer a pH between 6 and 7.5.

Therefore, when the soil is too acidic, you may have to add some soil amendments in order to make it neutral.

That said, a good variety of plants are better off staying in acidic soil,  and there are amendments for maintaining that as well.

This article discusses which plants can stay well in acidic soil and how can you test acidity.

Keep reading to know more!

pH scale

What Causes an Acidic Soil?

Most plants prefer pH levels between 6 and 7.5 because at that pH phosphorus present in the soil is soluble.

Phosphorus is one of the three essential macronutrients for the plant.

There is nitrogen phosphorous and potassium make up the NPK fertilizers. 

It allows the plant to bloom as well as set fruit.

Therefore, at that pH it lets the plants survive as they dissolve in water and are easily taken up by the plant roots.

Now that you know why the almost neutral pH is important for the soil, let’s dig into what causes it to become acidic in the first place.

acidic soil causes

Causes of Acidity 

  • Organic matter and minerals break down in the soil over time. These are generally acidic in nature. As they keep breaking down, they make the soil acidic too. This is more common in peat bogs and pine forests.
  • Using high nitrogen synthetic fertilizers. Synthetic nitrogen fertilizers are usually ammonia-based. Hence, that increases the acidity of the soil when used regularly.
  • Leaching because of irrigation and rainfall. When there is too much water, nutrients such as potassium, and nitrogen and when there is too much water, key nutrients such as potassium, calcium and magnesium seep out of the soil. All of these are crucial in preventing soil from becoming too acidic. Hence, the pH level of the soil begins to drop as they are washed out, acidifying it instead.

But how can you tell whether your soil has acidified?

For that, you will need a pH test.

testing acidic soil

Testing Soil pH

You can either send a sample to your local cooperative extension office or buy a test kit to know the pH yourself.

By sending a sample they will be able to give you a detailed analysis on the nutrient content in your soil along with the pH levels.

This way you can at least know about the nutrient deficiencies present in your soil and how can you tackle them later on.

The other option is using DIY soil pH testing kits.

These are present at garden centers and nurseries for your use.

You will need some litmus paper on hand and also soil samples.

Mix the soil samples with water and dip the litmus paper inside.

If you remember school chemistry, you must know that litmus paper indicates the pH of the solution.

In this case, it will tell you that of the soil.

Another way to check if your soil is acidic or alkaline is a simple but not as reliable home remedy.

We are sure you may have some vinegar at home.

Grab half a cup of that.

Simply collect soil in a container and mix the half-cup vinegar with it.

If it fizzes, then the soil is alkaline because vinegar and acid react with the soil that is alkaline.

On the contrary, you can replace vinegar with baking soda.

Moisten soil with distilled water and add half cup of baking soda.

If again, it fizzes, the alkaline baking soda reacted with the acidic soil.

You can get accurate results by sending your soil samples however, using a DIY pH test kit is not bad either.

You can also look into whether there are certain weeds growing in your garden.

The likes of Buttercup, Docks and Dandelion among others grow well in an acidic soil.

plants that grow well

Plants that Grow Well in Acidic Soil

Some plants and weeds do not need an alkaline or neutral environment.

In fact, they thrive well in an acidic environment instead.

The weeds include: 

  • Docks (Rumex spp.)
  • Nettles (Urtica dioica)
  • Eastern Bracken (Pteridium aquilinum)
  • Silvery Cinquefoil (Potentilla argentea)
  • Sorrel (Rumex acetosa)
  • Horsetail (Equisetum arvense)
  • Buttercup (Ranunculus spp.)
  • Dandelion (Taraxacum officinale)
  • Sorrel (Rumex acetosa)
  • Plantain (Plantago spp.)


  • Magnolia
  • Willow Oak
  • Beech
  • Evergreen Trees (most if not all)
  • Dogwood


  • Cranberries
  • Gooseberries
  • Currants
  • Strawberries


  • Rhubarb
  • Sweet potatoes and potatoes
  • Peppers



  • Caladium
  • Begonia
  • Foxglove
  • Trillium
  • Bleeding Heart
  • Japanese Iris

Suppose your soil is not acidic, then the plants which actually prefer an acidic soil will signal that through iron chlorosis.

This is iron deficiency which causes the leaf veins or the entire leaf to turn yellow.

In order to correct it, you may have to add soil amendment to the soil.

You can also fulfill the need for acid through a fertilizer that will specifically provide it.

However, there are also other ways to go about it. More on that below.

But first, if you decide on adding a soil amendment you should first get it checked.

This will help you know the current pH of the soil as well as the nutrients that your soil needs and should be present in the amendments.

You can get fertilizers and soil amendments at home-improving stores and garden centers.

Your acid-loving plants will just need a bit of it as well as some other stuff.

Let’s dig deeper into that below!

increasing soil acidity

Increasing the Acidity of Soil

Adding Iron Sulfate 

Iron sulfate can treat specific symptoms present in a plant that refer to iron deficiency.

It will lower pH, however, you will need a larger volume to get results.

Though, the results are quicker.

It can provide results within a matter of three to four weeks, however, if you use it excessively, it may also damage the plants.

The application includes digging into the soil as a powder.

You can also dissolve it in a solution and water over the leaves so that they absorb it.

Adding Aluminum Sulfate 

Powdered aluminum sulfate is quick acting and also easy to dig around the plants.

Therefore, it has already been a staple additive for blueberry gardeners.

Though with aluminum there is a risk of toxicity.

It can be absorbed from drinking water and aluminum sulfate used in excess can contaminate the groundwater supplies.

Thus, that poses a greater risk and can be especially dangerous for children.

Combined with water it can turn to corrosive sulfuric acid.

Now aluminum sulfate is only used on hydrangea flowers.

There it contributes to bringing the blue color.

Adding Sulfur

Sulfur is effective in decreasing pH, however, it takes a lot of time.

Therefore, you should add it in the soil a year before you actually intend to plant in it.

It is one of the best options to acidify your soil as it lasts inside effectively for years.

The method to apply is not around existing plants but before planting in spring.

Therefore, you should add it to the soil in summer or fall to plant in spring.

To know the amount of sulfur required, you should conduct a soil pH test beforehand.

That will tell the exact amount the soil needs.


Other Ways

Adding Acidic Fertilizer 

When the acid-loving plants are isolated among the other non-acid plants it is not best to amend the soil.

Here increasing the acidity by adding the amendment will affect the soil and all the other plants.

For that, you can specifically add the acid fertilizer to the specific plants.

Fertilize with water soluble products and only begin with mild solutions to first test if your plants grow well and the others are not affected.

Adding Ammonium Sulfate 

As another sulfur product, ammonium sulfate works to decrease the pH of soil.

However, it is much better than aluminum sulfate and it is dug in the soil around the base of growing plants.

Though, you should carefully and moderately use it.

Excess use of ammonium sulfate can burn plants quickly.

Adding Sphagnum Peat Moss 

In order to increase the acidity of the soil using peat moss, you will need to add large amounts of it.

Even then, it will only achieve slight acidity.

Moreover, you will also need to add organic material.

The application is before you plant.

While you are preparing to plant, add about four to six inches of peat moss to the topsoil.

Next, till it up to six inches deep.

This will help to acidify the soil for up to two years.

All of these will help to acidify the soil to help grow the plants that like growing in an acidic environment.


Most plants may prefer a 6.5 pH of soil.

An optimal pH allows the plants to absorb the nutrients it needs from the soil.

However, every plant requires a specific pH.

Some may prefer acidic soil rather than mostly requiring neutral.

For that, you can add these soil amendments and fertilizers to alter the soil accordingly.



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