If your plants are not thriving the way they should, the pH of your soil may be the culprit. A high pH in the soil means it is too alkaline. Even if your soil is rich, it can prevent your plants from absorbing essential nutrients. So learning how to lower the pH of your soil is key to creating a more balanced and fertile environment for your garden or lawn.
Whether you have a trend in Portland vegetable patches or landscaping your front yard in Charleston, South Carolina, reducing soil pH can make a huge difference in plant health and growth. This Redfin article covers everything you need to know about soil pH.
What is soil pH? Why is it important?
Soil pH is a measure of soil acidity or alkalinity on a scale of 0-14.
Acid soil: pH below 7 Neutral soil: pH of 7 alkaline soil: pH above 7
Most plants prefer a slightly acidic to neutral pH range of 6.0-7.0. Outside of this range, essential nutrients such as iron, phosphorus and manganese are less available, which can hinder growth and cause yellow leaves.
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What affects the pH of the soil?
Several factors can affect the natural pH level of the soil, including:
Soil composition: Sand soils tend to be more acidic, but clay soils often become alkaline. Rainfall: In areas with high rainfall, acidic soils are usually due to nutrient leaching, whereas in arid areas, alkaline soils may be increasing. Fertilizer Use: Some fertilizers, especially those high in ammonia, can acidify the soil over time. Organic matter: Decayed organic materials such as leaves and compost can release acids that lower the soil pH. Water Source: Irrigating with alkaline tap water can gradually increase the pH of the soil, but rainwater can help maintain acidity. Plant Uptake: When a plant absorbs nutrients, it can affect the pH of the soil, depending on the nutrients removed.
Understanding these variables will help to maintain the right balance of the plant and prevent future pH imbalances.
How to test the ph of soil
It is important to test the soil before making any changes. Here are some ways to do it:
Soil PH Test Kit: Widely available at Garden Centres or online. These kits often include color charts and solutions or pH strips. Digital pH meter: Provides a rapid and reusable method for accurately testing the pH of your soil. Lab Test: Local Co-operative Expansion Offices may offer affordable lab tests with detailed results and recommendations.
Once you know the pH of the soil, you can decide whether or not it needs to be lowered and how much it will take.
How to lower soil PH: Natural and chemical options
There are various methods that can be used to make the soil more acidic. A suitable approach will depend on the type of soil, current pH levels, and planning for growth.
1. Add elemental sulfur (slow but effective)
Best for: Long-term soil pH adjustment in garden beds or lawns
How it works: Soil bacteria convert the elemental sulfur into sulfuric acid, gradually lowering the pH.
Application Tips:
Use 1-5 pounds per 100 square feet, depending on the soil type and pH level. Thoroughly water after application. It may take months for the results to kick perfectly.
Expert Tips for Using Elemental Sulfur:
“We start by testing the soil to understand the baseline,” says Rockaway. “Elemental sulfur and aluminum sulfate are excellent at lowering pH, while organic matter like peat moss helps improve the structure while supporting acidification. Apply moderately and monitored regularly.
“To effectively reduce the alkalinity of the soil, we incorporate organic matter such as elemental sulfur or compost,” says Ascent Yard Care. “Although Elemental Sulfur is the most efficient solution, overuse can be harmful. Student applications and regular testing are important. Many homeowners make the mistake of spraying them all at once.
“Sulfur is one of the most effective modifications to lower the pH of the soil,” says Outdoor Transform. “It reacts with bacteria in the soil to form sulfuric acid. Within weeks to months, the results will be displayed depending on the structure of the soil. Do not apply excessively.
2. Use aluminum sulfate (fast option)
Best for: Flowerbeds and Potted Plants
How it works: React quickly with the soil to lower the PH
Caution: It can be harmful in large quantities. Closely to label instructions.
Note: Overuse can lead to aluminum toxicity, especially in acid-sensitive plants.
3. Incorporate acidic organic matter
Best: Gardeners who prefer natural or organic methods
example:
Pine Needle Pete Moss Composted Oak Leaves Coffee Ground
These modifications slowly acidify the soil and improve structure and nutrient retention over time.
Expert Tips for Lowering PH with Organic Materials:
“Our recommendation to lower the pH of the soil is to add organic ingredients like pine needles, compost and peat moss,” says a nursery nearby. “It works slowly and steadily. Aluminum sulfate is effective because it has fast results. Care must be taken when administering. Always test regularly and avoid the temptation to rush the process as it can damage the plant.”
“For best results, use organic modifications like pine needles, oak leaves, peat moss and more,” says Rogers’ Landscape. “Avoid water overring. You can leach the acid you are trying to introduce. Gradual changes are important. Surprising many modifications to the plant at once.”
“Spreading lime is one of the most effective ways to reduce soil alkalinity,” says Rockaway Landscape Rake. “Using a push-behind or tow-behind drop spreader ensures uniform coverage, and choosing a finer lime particle size will improve results. Just remember.
4. Apply acidified fertilizer
Some fertilizers are naturally acidic and help to lower the pH when feeding the plant. search:
Ammonium Sulfate Urea Ammonium Nitrate
Note: Take care not to over-bloat, which can harm the plants and contaminate groundwater.
Expert tips for using fertilizers adjust the pH of the soil.
“Fertilizers containing nitrogen can help reduce the pH of the soil over time, especially when applied slowly,” says B’s green tree. “As the label’s instructions, let it do that naturally, and trying it over can backfire.
“To regulate high pH soils, use acidic organic fertilizers. They add both acidity and useful microorganisms,” says the faithful chemical. “A slow, alkaline organic fertilizer is useful for low pH. Also, frequent watering can help dilute the pH of the soil, but the results will vary depending on the basic soil composition.”
5. Water with rainwater
Tap water can become alkaline, especially in areas with hard water. Switching to rainwater (naturally slightly acidic) can help maintain a low pH over time, especially in container gardens.
Best Practices for Lowering Soil PH
Not only is it about lowering the pH of the soil, but also choosing the right modification, but also using it wisely. Follow best practices supported by these experts to avoid common mistakes and give your plants the best chance to thrive.
Gradually adjust: If the pH is too fast, it can impact the plant’s roots and destroy beneficial microorganisms. Test before and after: Always test the soil before applying any modifications and retest every few months to monitor changes. Adjust the pH to the plant. Promotes more acidic states such as blueberries, azarices, and azarices (pH 4.5–5.5). Make sure you’re targeting the right range for what you’re growing. Don’t overdo it: Nothing more is always better. Overapplication of sulfur or aluminum sulfate can lead to nutrient lockouts and plant stress.
These steps help you achieve more consistent and long-term results without risking garden health.
Plants that prefer acidic soils
Certain plants thrive in acidic conditions and can benefit from lowering the pH of the soil. These include:
Blueberry Azalea Ajalgias (particularly for Blue Blooms) Rhododendron camellia Guarderia Hollys Mountain Laurel Lupin Magnolias Evergreen and conifers such as pine, fir, spray, juniper
These acid-loving plants often struggle in alkaline soils, and when the pH drops to the preferred range (typically 4.5-6.0), they show healthier growth, better flowering, and improved nutrient absorption.
Professional tips on how to cultivate acid-loving plants::
“Plants such as azaleas, rhodendrons and hydrangeas thrive in acidic conditions,” says Thuja Supply. “Evergreens, coniferous and flowering shrubs benefit most from lowering the pH of the soil. Adjusting pH supports healthier roots and vibrant flowers of these acid-loving species.”
“Naturally lowering the pH of the soil can be achieved using acidified biochar made from acidic ingredients,” says Safi Organics. “This improves soil structure and microbial activity over time, making it ideal for crops such as tea, coffee, and blueberries. For quick results, corrections such as elemental sulfur and peat moss work well, but they need to be applied carefully to avoid soil overcompensation.”
Common mistakes when lowering soil pH
Avoiding these pitfalls will help you achieve consistent and healthy results in your garden.
Overapplied Fixes: Using sulfur or aluminum sulfate can cause nutrient lockouts and plant stress. Skip Soil Testing: It’s easy to make a simple misjudgment if you need to do so or at all without testing before or after treatment. Do not adjust gradually: a rapid shift in pH can damage plant roots and destroy beneficial soil organisms. Using false fixes: Lime-based products increase pH rather than lowering it. So make sure you use the correct materials. Ignore the pH of water: Alkaline tap water can reverse the pH correction of the soil over time.
Avoiding these pitfalls will help you achieve consistent and healthy results in your garden.
Expert tips for lowering and managing soil PH:
“Regularly measuring the pH of the soil is essential for healthy growth,” says Bluelab Blog. “Elementary sulfur provides long-term solutions, while aluminum sulfate works more quickly. Organic options such as composted pine needles provide a natural way to improve acidity over time.
“Good drainage and sunlight are important when managing soil pH,” says Turf Titanz. “If you are applying lime, do so after soil testing. Yielding or winter is best. A common mistake is to use false corrections. Dolomite lime is cost-effective, but should only be applied when needed. Moss growth is often applied, especially for acid-loving plants like Azaleas and Rhodendrons.”
“Elemental Sulfur is the gold standard for lowering pH due to natural interactions with soil microorganisms,” says NPK Industries. “Organic materials like pine needles and compost work more slowly. Don’t overapply them, which can lead to nutrient lockouts. Frequent soil testing before and after correction can help avoid surprises and ensure optimal conditions for acidic plants such as blueberries and gardenias.”
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FAQ regarding lowering soil pH
1. What is the fastest way to lower the pH of the soil?
Aluminum sulfate works quickly and reduces the pH of the soil, but it must be used with caution to avoid plant damage.
2. Can I use vinegar to lower the pH of the soil?
Although vinegar is acidic, it only offers short-term effects and can harm beneficial microorganisms. It is not recommended for long-term soil pH adjustments.
3. How often should you test the pH of the soil?
If you are making adjustments, test the soil at least once per season. For general maintenance, only once or twice a year is sufficient.
4. What plants prefer acidic soils?
Blueberries, azaleas, hydrangeas, rhododendrons, and camellia thrive in more acidic soil conditions.
5. Is lowering the pH too harmful to the plant?
yes. Overoxidation of soil can limit nutrient intake and harm soil organisms. Always adjust slowly and retest frequently.
