When acidic fertilizers are mentioned, you might think about pouring some citrus juice into the soil to make it acidic. While we love some fruit juice, that’s not what acidic fertilizers are all about.
Acidic fertilizers help balance out soils that have become too alkaline. They’re also great for plants that love this kind of soil pH, so that’s another push to try acidic fertilizers.
In order to understand what they’re all about, let’s define acidic fertilizers, their types and examples, and the common mistakes to avoid. Let’s start!
Defining Acidic Fertilizers
Acidic fertilizers are formulas that make the soil more acidic due to their chemical composition. They contain compounds that release acidic ions as they break down benefitting certain plants.
Soil pH measures acidity or alkalinity on a scale from 0 to 14, with 7 being neutral. Values below 7 are acidic, while those above are alkaline.
Many plants prefer acidic soil pH levels. Acidic fertilizers, in general, help by providing nutrients and lowering soil pH, allowing them to take in some of their much-needed nutrients.
Benefits of Acidic Fertilizers
While most homeowners prefer neutral sol pH levels, there are several advantages when your soil leans slightly towards the acidic side. Let’s go through them one by one.
Optimized Soil pH for Acid-Loving Plants
Acidic fertilizers create and maintain the ideal soil pH levels for plants like blueberries, azaleas, and rhododendrons. Since these plants grow well in acidic soil, acidic fertilizers make it possible for them to flower and fruit.
Enhanced Nutrient Availability
Using acidic fertilizers helps your garden plants absorb nutrients better. Think iron, manganese, and phosphorus as your soil buddies that lead to better plant health.
Reduced Nutrient Deficiencies
You see, alkaline soils limit nutrient intake for your plants. By adding acidic fertilizers to the soil, your plants get to take in more nutrients as they sip them from their roots.
Flourishing Lawns and Landscaping
Acidic fertilizers are more than for just shrubs and trees. They’re also good for creating amazing lawns and landscaping in general.
Grasses like St. Augustine do really well in slightly acidic soils. If you want lush lawns and vibrant ornamental plants, acidic fertilizers might just be for you.
Improved Crop Yields
When you add acidic fertilizers to vegetable and fruit gardens, you increase the chances of better harvests and higher yields. For example, common garden vegetables like potatoes and tomatoes do great in slightly acidic soil.
Long-Term Soil Health
You might get so concerned about the short-term needs of your garden soil that you forget about long-term gardening goals. Acidic fertilizers add to the long-term health of garden soils by balancing pH and supplying them with essential nutrients.
When you have this soil condition, it supports the growth of beneficial microorganisms. In return, these microorganisms bring lots of benefits to your garden and its residents.
These tiny, almost invisible organisms are VIPs when it comes to improving soil aeration, recycling nutrients, and enhancing soil structure. As a result, your garden soil remains fertile and productive over time.
Choosing the Right Acidic Fertilizer
Now let’s talk about the factors that affect how we choose the right acidic fertilizer. We recommend selecting the best one to meet your plant’s needs.
Start asking yourself if the plants you’re planning to feed are acid-loving plants. Blueberries, azaleas, and rhododendrons are prime examples.
Or is it that you need to slightly lower the pH for various plants? You might want to think about your lawn and landscaping as well.
Basic Types of Acidic Fertilizers
There are 3 basic types of acidic fertilizers, grouped by common factors. These are ammonium-based fertilizers, sulfur-based fertilizers, and naturally acidic fertilizers.
Ammonium-based fertilizers provide nitrogen to plants. Since they can acidify soil to varying degrees, the amount applied should be carefully thought out.
Sulfur-based fertilizers are used to lower soil pH. These are often used for acid-loving plants such as blueberries as these fertilizers can moderately to highly acidify the soil.
Natural acidic fertilizers are used to enhance soil drainage and introduce organic matter. As time passes by, naturally acidic fertilizers lightly increase the acidity of the soil as the soil microbes break down the organic matter.
Get a Soil Test
A soil test is a foolproof way to determine if your soil really lacks acidity. Plus, a soil test helps you identify the nutrient levels in your soil.
This allows you to make the necessary changes to either balance it or amend it to align with your gardening needs. Plus, you get to have more fun and freedom when it comes to designing routines and setups for your garden.
Consider Application Method
Some acidic fertilizers are granular. This means they can be handled and spread easily on the soil surface.
Others come in liquid form for easy incorporation into the soil. Most of the time, they come in concentrated form and need to be diluted before being applied as sprays or soaks.
When it comes to picking the right acidic fertilizer, factor in the application method that works best with your gardening practices and your plant’s specific requirements.
16 Acidic Fertilizers
Figuring out how strong soil amendments and fertilizers are at lowering soil pH can be tricky. It depends on factors like the initial soil pH, the amount used, and the specific material.
Since there are so many acidic fertilizers available in the market, we’ve listed them down to help you decide faster at a more convenient style. Keep in mind that these rankings are approximate and may change based on local conditions.
Sulfur
| Factor | Information/Description |
| Acidic Strength | High ●●●●○ |
| Effectiveness | High |
| Ideal For | Adjusting pH in alkaline soils |
| Possible Risks | Over-application can harm plants and soil, causing nutrient imbalances and soil acidity levels that are too low for some plants. Careful use is essential. |
Sulfur is ideally used for acid-loving plants like blueberries, azaleas, and rhododendrons that prefer acidic soil. Just remember to use it with caution.
Too much sulfur can harm your plants and soil. This could end up causing nutrient imbalances and growth issues.
To make the most of sulfur’s benefits, follow application instructions carefully. Also, check your soil’s pH levels often to ensure the right acidity for your plants.
Ammonium Sulfate
| Factor | Information/Description |
| Acidic Strength | High ●●●●○ |
| Effectiveness | High |
| Ideal For | Acid-loving plants like blueberries, rhododendrons, and azaleas. Also provides a quick source of nitrogen for green growth. |
| Possible Risks | Overuse can lead to soil acidity levels that are too low and may cause harm to non-acid-loving plants. Careful application is necessary. |
This particular amendemtn offers a quick nitrogen source, promoting green growth in various garden plants. Excessive use can lower soil pH levels too much, potentially harming plants that prefer neutral or alkaline conditions.
To use this fertilizer effectively, apply it carefully. Regularly check your soil’s pH levels to keep them suitable for your specific plants.
Aluminum Sulfate
| Factor | Information/Description |
| Acidic Strength | High ●●●●○ |
| Effectiveness | High |
| Ideal For | Lowering soil pH, especially in areas with alkaline soils or for plants that prefer acidic conditions. |
| Possible Risks | Overuse can lead to excessive acidity, harming plants and microorganisms in the soil. Make sure to have precise application. |
This form of fertilizer is especially helpful in areas where the soil is naturally alkaline. It also benefits plants like hydrangeas and blueberries that prefer acidic conditions.
Using too much can make your soil too acidic. Too much acidity can harm your plants and the helpful microorganisms that live in the soil.
Just follow the recommended guidelines for applying Aluminum Sulfate to avoid these issues. Keep an eye on your soil’s pH levels to make sure they stay right for your plants.
Iron Sulfate
| Factor | Information/Description |
| Acidic Strength | High ●●●●○ |
| Effectiveness | High |
| Ideal For | Correcting iron deficiencies in plants, especially for those that prefer acidic soils. |
| Possible Risks | Over-application can lead to iron toxicity in plants, negatively affecting their health. Careful dosage is important. |
Iron Sulfate is excellent for fixing iron deficiencies in plants that prefer acidic soil. These plants include rhododendrons, azaleas, and some fruit trees.
When using this fertilizer, gardeners should avoid applying too much. Excess can lead to iron toxicity, which harms plant health and growth.
Measure the dosage carefully and monitor how your plants respond.
Monoammonium Phosphate
| Factor | Information/Description |
| Acidic Strength | Moderate ●●●○○ |
| Effectiveness | Moderate |
| Ideal For | Providing both essential nutrients, nitrogen, and phosphorus to plants. Suitable for a wide range of crops. |
| Possible Risks | Overuse can lead to phosphorus runoff, which may harm aquatic ecosystems. Use in moderation and consider environmental impact. |
This fertilizer provides essential nutrients like nitrogen and phosphorus, which are crucial for plant growth. This makes it suitable for various crops, such as veggies, fruits, and ornamental plants.
Don’t use too much of it though. Excessive application can harm local and surrounding aquatic ecosystems due to the phosphorus runoff from the fertilizer.
Diammonium Phosphate
| Factor | Information/Description |
| Acidic Strength | Moderate ●●●○○ |
| Effectiveness | Moderate |
| Ideal For | Providing both phosphorus and nitrogen nutrients to plants, suitable for a wide range of crops and garden plants. |
| Possible Risks | Excessive use can lead to nutrient imbalances and soil acidification. Precise application is necessary. |
This acidic fertilizer is versatile and works well for various crops and garden plants. It supplies phosphorus and nitrogen for growth and flowering.
One of its benefits is its balanced nutrient mix, which is helpful for soils that require both phosphorus and nitrogen. It’s suitable for different plants like vegetables, fruits, and ornamental flowers.
However, using too much can upset soil balance and raise acidity levels. To achieve optimal results, adhere to recommended application rates and consider soil tests to address your garden’s unique requirements.
Sphagnum Peat Moss
| Factor | Information/Description |
| Acidic Strength | Moderate ●●●○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Improving soil structure and water retention |
| Possible Risks | Overuse can lead to soil compaction and nutrient issues |
Sphagnum Peat Moss is often used to improve soil structure and retain water rather than provide nutrients. It works really well for amending heavy clay soils.
This acidic material works great at improving drainage in potting mixes. When used well, it creates a great environment for acid-loving plants like camellias and azaleas.
Just remember that excessive use can compact the soil over time. This can result in stunted or slow root growth and nutrient absorption.
Since sphagnum moss lacks nutrients, you may need to use additional fertilizers for plants with specific nutrient needs.
Cottonseed Meal
| Factor | Information/Description |
| Acidic Strength | Moderate ●●○○○ |
| Effectiveness | Moderate |
| Ideal For | Providing a balanced source of nutrients, including nitrogen, phosphorus, and potassium. Suitable for a wide range of plants. |
| Possible Risks | Excessive use can lead to nitrogen imbalances and harm plants. Proper application rates are essential for optimal results. |
Cottonseed meal has moderate acidity, providing nutrients like nitrogen, phosphorus, and potassium. It’s pretty great for acid-loving plants like azaleas and camellias.
This particular acidic fertilizer also works for many other plants in flower and vegetable gardens. But always remember, more isn’t always better.
Using too much of it can harm plants due to nitrogen imbalances. We highly encourage following recommended application rates and guidelines.
Soybean Meal
| Factor | Information/Description |
| Acidic Strength | Moderate ●●○○○ |
| Effectiveness | Moderate |
| Ideal For | Providing a slow-release source of nitrogen and improving soil structure. |
| Possible Risks | Excessive use can lead to nutrient imbalances. Proper application rates should be followed. |
One advantage of using soybean meal is its ability to slowly release nitrogen to support plant growth over time. It can also enhance soil structure, improving water retention and aeration.
Don’t overuse it, though. Doing so can lead to excessive nitrogen levels, harming your plants.
Just follow recommended application rates based on your specific plant’s needs and you’re good. Also, check your garden’s soil conditions regularly.
Alfalfa Meal
| Factor | Information/Description |
| Acidic Strength | Moderate ●●○○○ |
| Effectiveness | Moderate |
| Ideal For | Providing a slow-release source of nutrients |
| Possible Risks | Excessive use can lead to excessive nitrogen and affect pH levels. Use in moderation. |
Alfalfa meal has moderate acidity. It provides a slow-release nutrient source for plants, improving soil and promoting growth.
It contains essential nutrients like nitrogen, phosphorus, and potassium, along with organic matter for soil structure and water retention.
Excessive application can affect soil pH. To avoid imbalances, follow the recommended application rates on the product label.
Urea
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Promoting general plant growth |
| Possible Risks | Overuse can lead to nitrogen runoff and result in polluted water sources. You need to be precise during the application. |
Urea is a mildly acidic fertilizer that’s often used in gardening to encourage plant growth. It’s not as strong as some other acidic fertilizers but it can still be effective when used correctly.
Using too much can result in excessive nitrogen in the soil, leading to nitrogen runoff into water sources. This can harm the environment and cause water pollution.
Urea can boost plant growth but you have to make sure that it’s properly measured and applied.
Ammonium Nitrate
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Quick nitrogen release in certain conditions |
| Possible Risks | High nitrogen content can cause burning if over-applied. Use with caution, and avoid in certain situations. |
This material is effective for specific situations, particularly when you need a quick nitrogen boost for plant growth. Just be careful when using it as its high nitrogen content can harm plants and soil if overused.
Stick to recommended application rates to avoid overapplication or damage. Keep in mind that Ammonium Nitrate might not be the best choice for all gardening situations.
Different plants and soil types may benefit more from other fertilizers. Understand your specific gardening needs before opting for Ammonium Nitrate.
Compost
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Improving soil structure and nutrient content, enhancing microbial activity, and fostering healthy plant growth. |
| Possible Risks | Over-application may lead to nutrient imbalances and excessive organic matter accumulation. Proper usage and mixing are important. |
Compost is, by far, one of the most popular choices in gardening. It’s mostly due to its ability to enhance soil quality and support plant growth.
It’s also very rich in nutrients and suitable for various gardening needs. Compost improves soil structure, increases nutrients, and boosts microbial activity, benefiting plants.
With that said, it should be used in moderation to avoid nutrient imbalances and organic matter buildup. Properly mix with existing soil and apply at conservative or moderate rates.
Manure
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Improving the soil structure, adding nutrients, and increasing the microbial activity in various garden settings. |
| Possible Risks | Low to moderate risks. May contain weed seeds or pathogens, leading to potential issues if not properly composted. Handle and apply well. |
Manure has moderate acidity and effectiveness. It improves soil quality, adds nutrients, and boosts microbial activity.
Proper use enhances soil structure, moisture retention, and nutrient levels. Organic gardeners find it valuable for sustainable plant nourishment and soil health.
Manure might contain weed seeds or pathogens. Careful composting is essential to avoid garden issues.
Corn Gluten Meal
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Natural weed control, nitrogen source for lawns |
| Possible Risks | Can inhibit seed germination in desired plants if not used carefully. |
Corn gluten meal is valued for weed control and nitrogen supply for lawns. It doesn’t provide quick nutrients like some fertilizers, but it has long-term benefits.
This makes it popular for organic and sustainable lawn care. While it stops weeds, it can also hinder seed germination, including desired plants.
Use it where you don’t plan to sow new seeds or young plants soon. Its mild acidity suits various soils and plants but you should always think about its impact on seed germination.
Rice Hulls
| Factor | Information/Description |
| Acidic Strength | Low to Moderate ●●○○○ |
| Effectiveness | Low to Moderate |
| Ideal For | Improving soil structure, moisture retention |
| Possible Risks | Decomposition may deplete nitrogen over time. |
Rice hulls don’t strongly alter soil pH but offer essential benefits. They improve soil structure and retain moisture, especially suitable for plants like strawberries and potatoes that prefer well-draining, acidic conditions.
One advantage is their slow decomposition, providing long-lasting soil improvement. Just know that over time, they can gradually reduce nitrogen levels in the soil.
You can avoid this by using nitrogen-rich fertilizers as needed. Rice hulls work as a soil conditioner that add to soil health and structure.
Common Acidic Fertilizer Mistakes to Avoid
It can be tempting to just throw in all the acidic fertilizers that we can think of just to increase the soil pH, but we need to remember that it could be a mistake. This is not the only one, so we’ve listed some of the most common missteps that homeowners commit.
Over-Acidification of Soil
Some plants prefer acidic soil, but too much acidity can harm others. Monitor your soil’s pH and make gradual adjustments.
Ignoring Soil Testing
Always test your soil’s pH before assuming its condition. Soil conditions can change, so regular testing is crucial.
Inadequate Nutrient Management
Besides pH control, acidic fertilizers provide essential nutrients. Depending on what you use, the nutrients might not be enough for your plant needs.
Applying Fertilizer at the Wrong Time
Timing matters, so apply fertilizers according to the growth stages of your plants. Generally, fall to spring is the best time to apply fertilizers of all types, including those that increase soil acidity.
Incorrect Application Rates
Follow the recommended application rates on the fertilizer package. You can easily damage or kill plants by applying too much.
Neglecting Safety Precautions
You need to handle acidic fertilizers with care even if they seem harmless. We strongly recommend using sturdy protective gardening gear.
Always follow basic safety guidelines to avoid untoward incidents, whether it’s your basic gardening activity or operating tools and machinery.
Not Incorporating Fertilizer Properly
Remember that granular fertilizers should be mixed well into the soil and not just thrown on the surface. Doing so guarantees an even and thorough fertilizer distribution.
Use a garden fork or tiller, if you have to, to make sure everything gets mixed in.
Neglecting Long-Term Soil Health
You need to think beyond the immediate need for pH adjustment. Focus on long-term soil health instead.
Some of the things you can do are add more organic matter, practice crop rotation, and maintain nutrient balance. This will give you better and more fertile soils.
