How to make a natural soil acidifier: a complete guide to enhance your crops

Depending on the type of crop, it may be necessary to acidify the soil. To do this, you need to observe if the plants aren’t thriving as they should and whether the soil is alkaline, in which case acidification may be necessary. To learn everything about how to make a natural soil acidifier, don’t miss out on all the details we explain below.

Making soil acidic: what does it mean?

When we talk about making soil acidic, we refer to modifying the pH to make it more acidic, meaning reducing its value below 7. Alkaline soils have a pH above 7 and can hinder the absorption of certain nutrients by plants. This process is crucial for improving soil fertility and ensuring optimal crop development that requires acidic soils.

Why make a natural soil acidifier?

Some plants, such as blueberries, hydrangeas, or rhododendrons, need an acidic environment to grow properly. If grown in alkaline soils, they may experience nutrient deficiencies and poor growth. To acidify alkaline soil, it improves the availability of essential nutrients like iron, manganese, and phosphorus, allowing for better root development and greater nutrient absorption.

How to know when you should make soil acidic

Before learning how to make a natural , it’s important to know when to do so by considering the following factors:

Measuring soil pH

The first step is to measure the pH of the soil for marijuana using a digital pH meter, test strips, or DIY test kits. If the pH is higher than 7.0, it means the soil is alkaline and may require acidification if you plan to grow plants that need acidic soils.

Symptoms in plants

If plants show signs of nutrient deficiencies, especially of iron and manganese, it may be because the soil is too alkaline. Some symptoms include:

• Yellowing leaves with green veins (iron chlorosis).
• Slow or stunted growth
• Reduced flowering.

Type of plants to grow

If you want to grow species that require acidic soils (pH between 5.0 and 6.5), such as blueberries, hydrangeas, camellias, or rhododendrons, you will need to acidify the soil if it is alkaline.

In the case of marijuana plants, different strains prefer acidic soils. These can be classified as:

What type of soil needs to be acidified?

Soils with high pH (above 7), or alkaline soils, should be acidified naturally because they can hinder the absorption of certain essential nutrients for plants. Some examples of soils that need acidification include:

• Limestone soils: rich in calcium carbonates, common in arid and semi-arid areas.
• Soils high in sodium: also known as sodic soils, which can affect soil structure and nutrient absorption.
• Soils with excess decomposed organic matter: in some cases, the decomposition of certain materials can raise the pH.

These soils should be acidified when growing plants that require an acidic pH, such as blueberries, hydrangeas, rhododendrons, or azaleas.

How to make a natural soil acidifier?

To make a natural soil acidifier, several homemade and eco-friendly methods can be used. These not only improve soil fertility but also enhance moisture retention and aeration. The use of organic matter is one of the most effective and natural ways to improve soil quality, creating an ideal environment for root development while adjusting pH. These methods include:

Application of vinegar or citric acid

Diluting vinegar in water (one tablespoon per liter) or using citric acid in small doses can help quickly acidify the soil. Both products are natural acids that, when diluted in water, can lower the substrate’s pH and improve the absorption of essential nutrients such as iron and phosphorus. To use them, simply:

• Vinegar should be used in low doses (1 tablespoon per liter of water) and applied occasionally to avoid imbalances.
• Citric acid can be easily used by dissolving 1-2 grams in one liter of water.

Using elemental sulfur

Powdered sulfur is one of the best options to gradually and durably acidify the soil. When metabolized by soil bacteria, it turns into sulfuric acid, which gradually reduces the pH. This method is ideal for highly alkaline soils and crops that require a low pH, such as cannabis, blueberries, and hydrangeas. To use it, simply sprinkle it on the surface and distribute it evenly, keeping in mind the following:

• In sandy soils, to reduce the pH by one point, apply 50-100 g/m².
• For clayey soils, apply 150-200 g/m².

Coffee grounds

Coffee grounds contain natural acids that help lower the pH of the substrate, as well as provide organic matter and improve soil structure. Simply collect the coffee grounds after brewing and let them dry to prevent mold. Then, spread them over the soil.

Using peat moss

Peat moss is a natural acidic substrate that can be mixed with soil to lower its pH, and it can last for several years. It also improves water retention capacity. To apply it, use a ratio of 1 part peat to 2 parts soil, mixing it with the top 15-20 cm of soil, so it will be distributed across the root zone.

The amounts vary depending on the type of soil:

• Slightly alkaline: apply 5-10 cm of peat moss on the surface.
• Alkaline soils: more than 15 cm of peat moss.

Application of iron sulfate

Iron sulfate is a pH corrector that also prevents iron chlorosis in plants sensitive to alkaline soils. Apply it in the recommended doses by the supplier, sprinkling it around the base of the plants. Afterward, water abundantly.

Incorporating pine needles

Pine needles, when decomposing, add acidity to the substrate and improve its structure. This natural method for making acidic soil is very simple and economical. Just place the pine needles around the plant and wait for them to decompose.

Comparative table of methods for making a natural soil acidifier

Acidifying soil naturally is an accessible and beneficial process for many plants. With these methods, you can maintain an appropriate pH and improve the health of your crops.

Fertilizers for making acidic soil

There are specific fertilizers that can help maintain an acidic pH in the soil of your crops. Some of the most commonly used include:

Top Lemon pH-

Top Lemon pH- from Top Crop is a concentrated liquid solution of citric acid, ideal for acidifying irrigation water and improving nutrient availability in the soil. It is also used to clean drippers and irrigation systems, removing calcium deposits. Unlike other acids, Top Lemon does not alter the NPK proportions of the substrate. The recommended dose is 0.2 ml/L for hard water and 0.1 ml/L for soft water.

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pH- Boom

This product from Boom Nutrients is formulated with phosphoric acid (H3PO4) to effectively reduce the pH of irrigation water. Maintaining the correct pH allows plants to absorb nutrients optimally, preventing deficiencies or excesses. It is recommended to use pH- Boom at doses of 0.5-1 ml per 10L of water and measure the pH after application.

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pH Down by GHE

pH Down by GHE is an acidity regulator composed of nitric acid, phosphoric acid, and organic regulators. It allows you to adjust the irrigation water’s pH in a stable manner, maintaining appropriate levels for nutrient absorption. It is recommended to apply it gradually, stirring and measuring until the desired level is reached.

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