Coffee Grounds: Do They Lower Soil pH?

Coffee Grounds: Do They Lower Soil pH?

Coffee grounds are a popular organic material that many gardeners use to improve the quality of their soil. But one question that often arises is whether or not coffee grounds can lower soil pH. In this article, I will explore the relationship between coffee grounds and soil pH and provide a comprehensive answer to this commonly asked question.

The Basics of Soil pH

Before diving into the effects of coffee grounds on soil pH, it’s essential to understand what soil pH is and why it matters. Soil pH is a measure of the acidity or alkalinity of the soil. It is measured on a scale of 0 to 14, with 7 being neutral. A pH below 7 indicates acidic soil, while a pH above 7 indicates alkaline soil.

So why does soil pH matter? Well, the pH of the soil directly affects the availability of various nutrients to the plants. Some plants thrive in acidic soil, while others prefer alkaline soil. If the soil pH is not suitable for the plants you are growing, they may struggle to absorb essential nutrients, leading to stunted growth and poor overall health.

The Use of Coffee Grounds in Gardening

Coffee grounds have become a popular compostable material for gardeners. They are rich in essential nutrients, such as nitrogen, phosphorus, and potassium, which are vital for plant growth. Additionally, coffee grounds contain organic matter that improves soil structure, water retention, and drainage. But do they have any effect on soil pH?

The Acidic Nature of Coffee Grounds

Coffee grounds have a slightly acidic pH ranging between 6.2 to 6.8. This acidity is due to the presence of organic acids, such as chlorogenic acid. However, it is important to note that coffee grounds are not strongly acidic like lemon juice or vinegar. Instead, they have a mild acidic nature that can be beneficial for certain plants and soil conditions.

The Effect of Coffee Grounds on Soil pH

Now that we know coffee grounds have an acidic nature let’s dive into whether they can lower soil pH.

Neutral or Alkaline Soil Conditions

If your soil is already neutral or alkaline with a pH above 7, applying coffee grounds can be a helpful way to lower the pH towards a more acidic range. The mild acidity of the coffee grounds can gradually help balance the pH of the soil, making it more suitable for acid-loving plants like blueberries, azaleas, and rhododendrons.

However, it’s crucial to monitor the pH levels regularly as coffee grounds alone may not be sufficient to make substantial changes in soil pH. In some cases, incorporating other organic materials, such as peat moss or pine needles, may be necessary to achieve the desired pH levels.

Already Acidic Soil Conditions

If your soil is already acidic with a pH below 7, adding coffee grounds may further lower the pH, making it less suitable for most plants. In such cases, it’s advisable to perform a soil test and determine if applying coffee grounds would be beneficial or not.

Proper Application of Coffee Grounds

To make the most of coffee grounds in your garden while considering soil pH, it’s important to follow certain guidelines for their application.

Composting Coffee Grounds

To ensure the coffee grounds are adequately decomposed before use, it’s recommended to compost them first. Incorporating coffee grounds into your compost pile allows them to break down further and become a valuable component of nutrient-rich compost.

Using Coffee Grounds as Mulch

Coffee grounds can also be used as mulch around acid-loving plants. By applying a thin layer of coffee grounds on top of the soil, you can enjoy benefits such as weed suppression, moisture retention, and nutrient release. However, it’s important not to overdo it and maintain a balanced approach to avoid creating excessive acidity.


In summary, coffee grounds do possess a mild acidic nature that can help lower soil pH, particularly in neutral or alkaline soil conditions. However, it is crucial to monitor the pH levels regularly and consider other factors such as plant preferences and soil composition. Coffee grounds can be a valuable addition to your gardening routine, but it’s important to use them wisely and in moderation to ensure a healthy and vibrant garden. Remember to compost them first or use them as a mulch to further enhance their benefits. So go ahead, grab a cup of coffee, and put those coffee grounds to good use in your garden!

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