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How to Make Soil More Acidic Organically

A lower pH level allows certain plants to more effectively absorb nutrients from the soil so they can flourish. When soil pH is too high, it can pose problems for plant health and growth. For many plants, soil that is high in alkalinity makes it harder for plants to drink in nutrients from the soil, which can limit their optimal growth.

Making your soil more acidic can be challenging because water is often alkaline, and limestone within the soil is regularly breaking down, also increasing alkalinity.  Fortunately, there are some organic methods that have proven to be very useful in lowering soil pH in gardens. Here are some suggested ways to make the soil more acidic organically.

Green plants and woman farmer measure PH and moisture in the soil with testing device

Test Your Soil

It is essential you analyze your soil to help understand the pH level. You can obtain a simple test kit at your local garden center. This results will help guide you on next steps to amend your soil accordingly.

The pH scale ranges from 0 to 14, with 7.0 being neutral. pH levels that are 0 to 6.9 are acidic, and measurements in the range of 7.1 and 14.0 are more alkaline. The general goal for vegetable gardens is to have a pH of around 6.5, although there are plants whose ideal pH growing environment varies from those parameters.

Amend Your Soil with Well-Decomposed Compost

Add plenty of organic matter each time you plant in your garden. Well-decomposed compost helps lower the pH of garden soil over time. Amending your soil each season with compost, which is rich in organic matter, is by far the best way to make your soil more acidic because it is done gradually and creates the most benefits for plant growth.  It also improves the soil structure and adds beneficial micro-organisms into the soil.

Kellogg Garden Organics

All Natural Potting Mix

Compost in wooden box on sidewalk

Compost Tea

Watering your plants with compost tea can also help make the soil more acidic organically. It is also a great way to feed your plants with fast-acting nutrients. Just take a five-gallon bucket of water and let it sit out in the sun for 24 hours to allow any chlorine to release from the water. Dump some well-decomposed compost into the bucket, usually 1-2 cups per gallon of water, and stir it periodically over 48 hours so that it steeps well. Strain the soil from the liquid. Pour the liquid in a sprayer and use as a foliar feed or simply pour it into a watering can and water your garden with it. Work the solids into the soil at the dripline around the plant(s).

Elemental Garden Sulfur

Applying organic, elemental garden sulfur is a safe and efficient way to make the soil more acidic. Sulfur is an essential nutrient that can bolster disease resistance in plants. It is important to follow the instructions on the package when it comes to this nutrient. Although it is beneficial to plants and can lower the pH of your soil dramatically, it can also have adverse effects on your plants if you overdo it.

Red mulch on the shovel and in the wheelbarrow

Mulch

Use organic mulch in your garden beds. The material will break down over time, helping to make soil more acidic in the process. Mulching with pine needles or oak leaves can provide an acidic boost. Organic mulches are beneficial for many other reasons as well, such as reducing soil erosion, retaining moisture, regulating temperature, and the release of beneficial nutrients into the soil.

Coffee Grounds

Don’t underestimate the power of your morning coffee! Save those coffee grounds and sprinkle them around your garden or add them to your compost pile. As coffee grounds break down, they will also contribute to making your soil more acidic.

Coffee residue is applied to the tree

Sphagnum Peat Moss

Adding peat moss to your garden soil can also help to lower the pH of your soil gradually. Peat moss is an excellent soil amendment for acid-loving plants and is easy to incorporate into the soil.  Simply add two to three inches to the top of the soil and work it into the layers of topsoil underneath.

Peat moss has lowered in its popularity in recent years both for the cost for expansive gardens and the fact that it is not a highly renewable resource.  There is also some controversy on what its harvesting process does to contribute to global warming.

Maintaining Your Soil

It can be a constant struggle for gardeners to maintain the correct levels of acidity in garden soil. Test your garden soil periodically to see where it lies on the pH scale and amend accordingly. Another tip is to consider what you are using to water your garden. Ideally, the most sustainable method is to collect natural rainwater in buckets, rain barrels, or watering cans to best imitate nature. Sometimes, water from the garden house can be very hard water with a high pH, which can also impact pH of your garden over time.


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4 Comments

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  1. what product do you make that will amend a 14 sq. ft garden space with a current pH of 7 to bring the pH down to between 4.8 – 5.5 for potato growing, or some sites say to pH of 6 maximum for potato growing?

  2. Very good info indeed.
    But there is some shortcoming!
    The use of various media discussed have not been quantified.
    (For example: how much tea leaves, coffee grounds should be used in how much soil.)
    And if any material is used (for example: tea leaves etc.) for how many days.
    Please add these info in the write-up too.
    Thanks.

    • Hi Sayef, when adding coffee grounds to your soil to adjust the acidity spread a thin 1/2 inch layer of grounds over the top of your soil. It is recommended to scratch the coffee grounds into your soil at a depth of 6 to 8 inches. If you’re applying tea leaves as mulch, simply place a 3 to 4 inch layer on top of the soil, try not to let the leaves touch your plants. They will break down and release their nutrients slowly over time, reapplication rates will vary. If you’re using compost tea in a vegetable garden, apply it once every two weeks and if applying to flower beds use once every 3 to 4 weeks. Compost tea should only be applied in the early morning or in the evening after the sun has set as direct sunlight can damage the plants. We hope this helps, happy gardening!

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