How to Lower pH in Soil: Why, When, and How?

how to lower ph in your soil

Sometimes, we gardeners encounter issues with our plants that we can’t entirely solve above ground. That’s when we need to look below and discover if something is happening in the earth itself.

Upon investigation, you may discover that your soil pH is too high, in which case you will need to figure out how to lower the pH in the soil?

How to lower pH in soil? I found the most common method of lowering soil pH is using aluminum sulfate. However, if you want the go the natural route, you can also use well-decomposed compost.

The pH balance in your soil is very delicate, but with some extra know-how, we can help you bring it to the perfect level for your garden to thrive.

In this article, we will be looking at exactly why you might need to lower your soil’s pH and how you might go about doing that.

Grow Your Yard Fact
Sulphuric acid, or, as it is also known, battery acid, is a speedy way to lower your soil pH, but it is very dangerous, so it is not recommended for home gardeners.

Why Do You Need to Lower Your Soil’s pH?

There are two main reasons you may want to lower your soil’s pH: if it is too alkaline and you need to make it slightly more acidic or because you require more acidic soil for a particular plant.

The pH level of your soil is measured on a scale of 0-14, with 0 being very acidic and 14 being very alkaline. These levels depend on the minerals in the soil and can be affected by climate, particularly rainfall, and soil texture like loamy, sand, or clay.

Having a pH level that is too low or too high can affect the plants’ ability to absorb nutrients as well as stunt their growth.

There are a few signs you can look out for when you suspect that your soil pH is too high:

  • Stunted growth
  • Leaf necrosis
  • The tips of new leaves dying
  • Brown spots on leaves

The best way to confirm that your soil pH level is the issue is to use an at-home testing kit (we recommend this one from Amazon). These can be purchased affordably from nurseries and garden stores. Follow the instructions on the packaging, and you should get a reading.

High pH (7.5 and above )- Alkaline soil

Neutral pH (7)-  Neutral soil

Low pH (6.5 and below)- Acidic soil

If your soil pH reads between 7 and 7.5, it is a sign that your soil might benefit from lowering the pH.

We suggest retesting every three months after you have tried to fix the issue to determine whether it needs to be repeated.

Grow Your Yard Fact
It is a rare occurrence, but some places, like some parts of  Wisconsin, have natural soil pH of over 7.5. When soil is this acidic, soil amendments like the ones we are going to suggest will not be effective because the soil is too alkaline.

How Do I Lower My Soil’s pH?

So, you’ve realized that your soil pH is too high; what now?

There are several ways you can lower your soil pH:

Aluminum Sulfate

The quickest and easiest way for a home gardener to lower soil pH is using aluminum sulfate.

This relatively cheap solution can be purchased from your local garden store.

Simply follow the instructions on the packaging for quantities and spread evenly over the area. Dig over the bed to let it work into the soil, and you’re ready to go.

Since it is so soluble, aluminum sulfate is quick-acting and economical, especially when dealing with a large area.

If you want an at-home solution that goes the more natural route, you can try:

Well-Decomposed Compost

We love using compost because it is so good for your soil, and it can be made for no money at home. To ensure that your compost is well-decomposed, we suggest filling it and turning it regularly before leaving it to decompose for at least six months before you use it.

Conversely, you can also buy compost from a garden store.

This method will add vital nutrients to the soil, but it is a slow-acting method compared with soil amendments like aluminum sulfate.

Coffee Grounds

This method can be used cheaply at home at no extra cost.

Simply keep your coffee ground aside after every use and, when you have enough, sprinkle them across the area. Work them into the soil well after applying to help along the process.

On the other hand, you can combine this step and the compost we mentioned above by adding the coffee grounds directly to your compost.

Grow Your Yard Tip
If you are struggling with soil pH significantly when growing vegetables, you can fix this issue by building a raised garden bed. This will allow you to customize your soil to achieve the perfect pH for your plants.

Which Plants Prefer What pH Level in Soil?

Each plant is unique in its own right, so it’s only natural that some of them may enjoy different soil pH levels.

Knowing your plant’s preferences is essential to growing to the best of its potential.

Here are a few plants that require a specific pH level to thrive.

Plant pH level
Blueberries, hydrangeas, rhododendrons, azaleas 5.0-5.5 (acidic)
Vegetables, grasses, ornamental 5.8-6.5 (slightly acidic)
Lavender, lilac bushes, yew, Boston ivy Over 7 (alkaline)

This may seem overwhelming, but we suggest dividing your garden into sections according to the soil pH they require so everything can grow in harmony.

When is the Best Time to Lower Your Soil’s pH

The best time to use one of the methods we discussed above is before planting your new plants.

This may not always be possible if your plants are already established, so we suggest doing a soil test before planting anything new.

We recommend doing this test before your spring planting or your fall bulb planting to make sure your plants have the best chance to grow large and strong.

Frequently Asked Questions:

Will Epsom salts lower soil pH?

Some suggest that, since it contains a percentage of sulfur, that Epsom salts can be used to lower the soil’s pH.

Unfortunately, Epsom salts don’t contain the crucial hydrogen ions needed to effect the soil pH, and, as a result, they have a neutral pH that will not do anything to the soil.

Is clay soil alkaline or acidic?

If you have clay soil in your garden then you are probably dealing with alkaline soil that could benefit from organic matter like compost.


As you can see, an unbalanced soil pH can have some adverse effects on your garden but there are some easy fixes that will help you solve it.

Whether you want a quick solution that you can buy or you want to take the slow, natural route, we have all the options you need to make the right decision for your garden.

All in all, we suggest aluminum sulfate for a quick fix and homemade compost as a long-term solution that has the added bonus of reducing your food waste.

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