How to Remedy Alkaline Soil for Better Gardening Results

Gardening success often depends on the quality of your soil and we can’t express how important that is in Idaho where soil around the Treasure Valley is often alkaline. Alkaline soil can hinder plant growth and nutrient absorption. Alkaline soil, where the pH level is above 7, means it’s less acidic and often rich in calcium carbonate. This condition can cause nutrient deficiencies, especially in iron, manganese, and phosphorus, leading to poor plant health. Fortunately, there are several effective ways to remedy alkaline soil and create a better garden environment.

Understanding How to Remedy Alkaline Soil

Before you start amending your soil, it’s important to understand what causes alkalinity and how it affects your plants. Alkaline soil typically occurs in areas with low rainfall such as we experience here in the Treasure Valley.  The high pH can lock up essential nutrients, making them unavailable to plants.

To remedy alkaline soil, we need to lower the pH to a more neutral or slightly acidic range, ideally we recommend between 5.8 and 6.5. This adjustment improves nutrient availability and promotes healthier root development.

Practical Steps to Lower Soil pH

1.   Test Your Soil pH 

Use a soil testing kit or send a sample to Western Laboratories in Parma, Idaho. Knowing your soil’s exact pH helps you apply the right amendments. They will provide customers how to correctly collect soil samples which is important to follow.

2.   Add Organic Matter 

Incorporate compost, peat moss, or well-aged manure. Organic matter improves soil structure and gradually lowers pH by increasing microbial activity. The best compost is composed of straw as bark can take away nitrogen from the plant.  Canadian Peat is the best peat moss as it contains a lower Ph than American peat moss. Well-aged manure can be either chicken or steer. We recommend staying away from horse manure.

3.   Use Acidifying Amendments 

·         Elemental sulfur is a common and effective soil acidifier. Soil bacteria converts sulfur to sulfuric acid, which lowers pH over time.

·         Aluminum sulfate works faster but should be used carefully to avoid toxicity.

·         Iron sulfate also lowers pH and adds iron, which is often deficient in alkaline soils.

4.   Mulch with Pine Needles or Oak Leaves 

These natural materials acidify the soil as they decompose.

5.   Avoid Overuse of Lime or Wood Ash 

These materials increase alkalinity and absolutely should be avoided if you want to lower soil pH.

Adding organic compost to soil to improve acidity

Effective Ways to Remedy Alkaline Soil for Your Garden

Once you understand the basics, you can apply specific techniques tailored to your garden’s needs. Here are a few recommendations:

Choose Plants That Tolerate Alkaline Soil

If you want a quick fix or have limited time for soil amendments, select plants that perform better in alkaline soil. Examples include:

• Lavender

• Lilacs

• Clematis

• Yarrow

• Sedum

These plants are naturally adapted to higher pH soils and will perform well without extensive soil modifications.

Garden bed with mulch and plants suited for alkaline soil

Apply Soil Amendments Gradually

Lowering soil pH is a gradual process. Apply amendments in small amounts and retest the soil every few months if possible. Over-applications can harm plants and soil life.

Improve Soil Drainage and Aeration

Alkaline soils can sometimes be compacted or poorly drained. Aerate the soil by tilling where possible. Good drainage also helps beneficial microbes thrive, which supports the pH of the soil.

Use Fertilizers Designed for Acid-Loving Plants

Fertilizers containing ammonium sulfate or sulfur-coated urea can help acidify the soil while providing nutrients. As we have stated in a prior blog, not all fertilizers are created the same.  We highly recommend Ferti-lome and Natural Guard products. Both produce outstanding results and both are produced by farmers who make their living using the right products for the application intended.

Does Epsom Salt Help Alkaline Soil?

Epsom salt, chemically known as magnesium sulfate, is often recommended for various gardening uses. However, when it comes to remedying alkaline soil, its effectiveness is limited.

What Epsom Salt Does

• Provides magnesium and sulfur, essential nutrients for plants.

• Can improve nutrient uptake in magnesium-deficient soils. The affects of a low pH and magnesium deficient appear nearly the same, however alkalinity is much more common in our area. That’s were a soil test comes in, their test will guide you in the right direction.

What Epsom Salt Does Not Do

• It does not lower soil pH or reduce alkalinity.

• It does not acidify the soil like elemental sulfur or aluminum sulfate.

When to Use Epsom Salt

Use Epsom salt if your soil test shows magnesium deficiency, which can occur in alkaline soils. It can help plants like tomatoes, peppers, and roses grow better by improving chlorophyll production and nutrient absorption.

How to Apply Epsom Salt

Applying liquid fertilizer with Epsom salt to garden plants

• Dissolve 1 tablespoon of Epsom salt in a gallon of water.

• Apply as a foliar spray or soil drench every 2-4 weeks during the growing season.

While Epsom salt supports plant health, it should be part of a broader soil management plan rather than a sole solution for alkaline soil.

Long-Term Strategies for Maintaining A Balanced Soil pH

Remedying alkaline soil is not a one-time task. Maintaining a balanced soil pH requires ongoing care and attention.

Regular Soil Testing

Test your soil at least once a year to monitor pH changes and nutrient levels. This helps you adjust your soil management practices accordingly.

Incorporate Organic Mulches

Mulching conserves moisture, suppresses weeds, and slowly acidifies the soil as organic materials break down.

Avoid Excessive Fertilizer Use

Over-fertilizing can increase soil alkalinity. Use fertilizers according to soil test recommendations and choose acidifying options when needed. Ferti-lome “GreenMaker” is an outstanding choice!

Encourage Soil Microbial Activity

Healthy soil microbes help convert sulfur to acid and improve nutrient cycling. Avoid chemicals that kill beneficial organisms.

By following these long-term strategies, you can create a sustainable gardening environment with soil that supports vibrant plant growth.

Enhancing Your Garden’s Potential with Soil Care

Remedying alkaline soil is a key step toward achieving better gardening results. By understanding your soil’s pH, applying the right amendments, and adopting good gardening practices, you can transform challenging soil into a fertile growing medium.

Remember, patience is essential. Soil pH changes gradually, and consistent care will yield the best outcomes. Whether you choose to amend the soil or select plants suited for alkaline conditions, your garden will benefit from thoughtful soil management.

Happy gardening…