How to Make Soil More Acidic? – 10 Methods

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Even though high soil acidity is often seen as a bad thing, it is not always the case. Some plants thrive on acidic soil. Others need a bit more acidity than usual to grow. Either way, learning how to make soil more acidic can help you enormously.

However, increasing the soil’s acidity is not a usual thing to do, so you may be struggling to find a helpful guide. Here, we bring precisely that. This is a guide with all the info necessary to start bringing that acidity level up no matter your needs. 

You’re learning how to bring pH levels down in 10 different ways, how to test acidity, what plants thrive on acidic soils, and much more. If you’re ready for the nitty-gritty – then let’s not waste any time!

What is Soil Acidity?

How to Make Soil More Acidic

Before diving deep into the matter, let’s give you a heads-up about acidity. 

First off, you have to understand it’s all about the soil’s pH. This pH is a unit of measurement for the concentration of hydrogen in the soil. The more hydrogen, the more alkaline the soil is, so the less acidity you will find. With low hydrogen ions, the soil ends up being acidic. 

The way to measure this pH is by using a scale that goes from 1 to 14. Every level in this range means a 10x change from the previous level. For example, soil with a pH level of 5 will be 10x more acidic than soil with a pH of 6. Compared to soil with a pH of 7, the one at level 5 will be 100x more acidic.

It is essential to mention that highly alkaline or acidic soils are often not ideal for plants. Both tend to lack essential nutrients that only thrive within 6.5 and 8.5 pH. Anything lower than that is known as a highly acidic soil. Above 8.5 pH is too alkaline. 

How to Increase Soil Acidity? 10 Methods that Work?

Now we can get into the real focus of this article. Because increasing this acidity is not a typical endeavor, we’ve assembled the easiest methods to tackle. Without much further ado, check them up: 

#1. Well-Decomposed Compost

Well-Decomposed Compost

Compost needs to be well-decomposed. But when it comes to augmenting acidity, this gets a slightly different meaning.

You don’t need just any compost but the most putrid and decomposed one. If you made your own compost, then it needs to have at least a month to decomposing. Anything lower than that won’t make it for the job.

Compost does add organic matter that is already at a high acidic level due to the decomposition. But because it is organic matter, the nutrient level is outstanding and makes it the best way to increase acidity. 

#2. Compost Tea

If adding compost directly to the soil is no longer an option, you can always use compost tea. As the name says, it is sort of an infusion of compost. By mixing all the organic material that makes compost but with water, it becomes a heavy beer-like liquid that works as a healthy drink for plants.

The way to use this is by merely watering plants with it. Due to the mixed organic material in the liquid, this water will contain all the microorganisms and nutrients that make compost so useful. 

More importantly, it will help level up the soil’s acidity, almost like ordinary compost would. 

#3. Vinegar

How to Increase Vinegar for soil

What better to increase the acidic level of soil than an acidic ingredient itself? That’s precisely what vinegar can do with proper application.

It is crucial to remember that vinegar is dangerous to plants as well. You must apply only 2 tablespoons on a gallon of water and then spread it around the soil.

Apart from using only a bit of vinegar, you must also be careful where you spread it. For the best experience, avoid watering plants directly and instead use it on the soil. 

#4. Garden Sulfur

Also known as elemental garden sulfur, it usually comes in bags of granules. These granules contain about 90% sulfur and 10% bentonite. The combination helps lower down pH levels exponentially while adding slight mineral touches for fertility. 

One advantage of garden sulfur is how easy it is to use. By simply spreading it evenly around the soil or area you want to cover, the sulfur will get the job done super-fast.

Of course, it is not entirely safe. If you overuse it, your plants may get damaged over time. To prevent that, read the instructions before applying. 

#5. Iron Sulphate

How to Make Iron Sulphate

Similar to sulfur, you can find iron sulphate. This one is a milder alternative for lowering soil pH. That means you’re going to need a lot more iron sulphate to get the job done.

However, needing more also means it is a bit more dangerous to use. If you overuse it, you may cause permanent damage to the soil and plants around. 

To apply iron sulphate, you’ll have to dig the soil and use it as a powder. Some iron sulphates come in liquid presentations. 

Because you’re going to need a lot more, it is mostly recommended for soils that lack iron. Also, it acts super-fast, changing the soil pH in just a few weeks while giving plants a bluish tone.

#6. Aluminum Sulfate

When growing berries and blue flowers, gardeners often use aluminum sulfate for its chemical potency. 

The application consists of digging around plants and pouring the powder in. Typically, two to three weeks should be enough to enjoy a change in acidity.

Even then, aluminum sulfate’s effectiveness comes with several drawbacks. This includes its toxicity, making it super-dangerous for children and pets. 

Also, it can get into wells and other groundwater supplies, causing problematic contamination. And in some cases, it may scorch plants if use on leaves or stems. 

#7. Acidic Fertilizer

Containing ammonium sulfate, nitrate, and sulfur urea, an acidic fertilizer, can help you bring that pH level down without causing much harm.

Despite being a fertilizer, however, the ammonium content can be slightly dangerous to plants. If misused, it may cause irreversible damage.

As a fertilizer, it is easy to apply. It also comes in a powdery mix that you can use directly on the soil—no need to dig or mix in the slightest, saving tons of time.

More importantly, it adds fast. Because of that, you can expect excellent pH changes in four weeks or less. 

#8. Mulch

Make Soil More Mulch

If you can get well-decomposed compost, then you can always pick mulch for the job. This is one of the safest ways to achieve lower pH levels and increase acidity.

The process is simple. You need to spread the mulch on the soil and let it do the job. Generally, it is recommended to use leaves as mulch for their rapid decomposition.

If you want to go for something more practical, an organic mulch mix also gets the job done. Either way, mulch may avoid erosion, add extra nutrients, and retain moisture to give a more fertile soil semblance. 

#9. Coffee Grounds

You don’t need to ground coffee beans for this. Whatever is left after infusing the coffee will be enough to bring that acidity up. Just pour on top of the soil, mix a bit, and that’s it. 

Coffee grounds have an excellent advantage is that they offer tons of nutrients as well. Along with their high level of acidity, coffee grounds can help make your soil more fertile in a month or two.

Like mulch, however, coffee isn’t as fast as other alternatives. But with patience, you can lower the pH level on a budget (while reducing waste from your daily coffee).

#10. Sphagnum Peat Moss

Acidic for Sphagnum Peat Moss

Last but not least, you will have sphagnum peat as an excellent alternative. This moss works like a charm on small gardens where you don’t have to spend an eternity applying it.

To make it work, you need to make a thin layer of moss over the soil you want to change, and that’s it. A few weeks and the acidity will start to increase. 

What sets it apart is that moss works gradually. You can apply it consistently and get mild pH level changes without overdoing it. 

Such safety makes it a renewable option as well. Being a plant itself, you won’t have to worry about any damage. 

Why Change Soil Acidity?

There are many reasons for this. Probably the most common is to bring high pH levels to more plant-friendly levels. For example, soil with 10 pH will not grow most plants properly due to the high amount of calcium and potassium. To make it fertile, you’ll need to bring that pH down.

And the second most typical is to match the needs of individual plants. They can be shrubs, flowers, fruity, or even vegetables. When they need acidic soils, even at normal pH levels, they may not sprout. The only solution is to increase the acidity.

What Plants Thrive in Acidic Soil?

While some plants only grow in acidic soils, others can thrive with proper care and nourishment. Some of these plants are popular, while others you may have never heard of. 

Either way, we identified them in flowers and turfs, vegetables, and fruits. Depending on what you’re looking to plant on acidic soil, you may find an excellent companion on this list. 

1. Flowers & Turfs

Plants Thrive in Flowers & Turfs

Because some flowers can grow in the most inhospitable places, you’ll find a lot of them to be acidity lovers. These are some of them:

  • Azaleas 
  • Hydrangeas 
  • Camellias
  • Gardenias
  • Magnolias
  • Lilyturf
  • Trillium
  • California Lilac
  • Summer Heather
  • Firecrest
  • Bilberries
  • Japanese Pachysandra
  • Blue Ageratum
  • Bunchberry
  • Anemones
  • Heath
  • Viburnum Bushes
  • Bottlebrush Shrubs

2. Fruits

Plants Thrive in Fruits

It is not common for fruitful plants to grow on acidic soils. But most berries can handle it, as well as other surprisingly resistant ones like:

  • Apples
  • Blueberries
  • Cranberries
  • Currants
  • Gooseberries
  • Grapes
  • Raspberries
  • Strawberries

3. Vegetables 

Plants Thrive in Vegetables 

At the ideal range, tons of different vegetables can sprout and thrive for years. Some of them include:

  • Beans
  • Broccoli
  • Cabbage
  • Carrots
  • Cucumbers
  • Evergreens
  • Onions
  • Parsley
  • Peppers
  • Sweet Corn
  • Sweet Potato
  • Tomatoes
  • Turnips. 
  • Squash
  • Radish
  • Rhubarb

How to Test Soil Acidity? 

Before you start adjusting the acidity, it is always recommended to know the soil’s pH level first. For that, you’ll have to analyze it first.

You can do it with a commercial test probe or with paper test strips (litmus strips). 

Either way, you’ll want to make sure the pH levels are not lower than 6. Anything lower than that won’t need any acidity change. But if the pH level is above 7, you may proceed by adjusting the soil pH as necessary. 

You can check our guide on how to test and adjust soil pH. It will help you, enormously. 

How to Maintain High Acidity Levels?

Once you start lowering the soil’s pH levels, you’ll find that it eventually rises alone. While re-applying one of the methods above may get the job done, there are other ways to keep that acidity high without any of that. Here are some tips to consider:

  • Avoid watering plants with regular tap water from the hose. If your home water supply is hard, filled with all kinds of minerals, it will eventually raise pH levels. Instead, collect rainwater on a rain barrel or reverse osmosis water that doesn’t contain many minerals. 
  • Ensure a sunny location. Lack of sun rays makes for a perfect area where bacteria can thrive. When this happens, organic matter starts to spread minerals around that increase pH levels. Sunrays keep that from happening. 
  • Reduce humidity. Like constant sun exposure, you’ll want to keep the soil as dry as possible (within a safe range). High humidity will eventually grow bacteria and increase mineral levels that promote alkalinity (opposite of acidity).
  • Keeps plants growing in the soil. Believe it or not, plants themselves are excellent acidity risers. When no plants are growing, the pH levels start to rise automatically. 

Following these quick tips should be enough to ensure a more acidic soil with no drawbacks over a long period. 


So, did you learn how to make soil more acidic? With such a brief yet comprehensive guide, you should be ready to tackle the job.

Be aware that some of these methods can be dangerous to the soil and plants, sometimes even to pets and children. Because of that, you must always follow instructions and apply with care. Otherwise, you may regret it. 

No matter how you proceed, follow our advice. These methods are more than adequate, so there’s nothing else to look after. We hope our guide was enough so you can start right away. Get your hands dirty now!

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