How To Make Soil Acidic For Rhododendrons – A Guide To Spectacular Flowering Displays

Last Updated on October 11, 2022

This article explains how to make soil acidic for rhododendrons. The method that we use helps to keep your plants healthy and strong. It also helps in the growth of your plants. We provide tips and advice on making acidic soil for rhododendrons.

Whether you’re a beginner or a seasoned gardener, the information below will be of benefit. It is important to know whether the plants that you grow like acidic soil or not. Therefore, knowing improving acidity in your garden is vital.

Acidic soil is one of the key factors in preventing disease in rhododendrons and azaleas. Rhododendrons thrive in soil with a pH level of around 4.0 and below. There are several ways to make acidic soils, and the methods listed below are a good starting point.

What To Consider When Planting Rhododendrons

When planting rhododendrons, there are a few things that you should consider to grow your plant healthily and help it thrive. Listed below are some vital tips that you should think about when planting rhododendrons.

Size of container

Smaller containers (4″) should be used for single-stemmed plants. Larger containers (10″) can be used for double and multi-stemmed plants.

Soil mixture

Various soil types can be used to grow rhododendrons. However, knowing how to make soil acidic for rhododendrons is vital to maintaining happy plants.

Depth of planting

Rhododendrons prefer to be planted at least 3″ deep. 


Keep your soil mixture moist. Rhododendrons like to stay moist. However, if you overwater too frequently, the leaves will start to turn yellow and wilt.


The main thing to remember about positioning is that your rhododendrons need to receive sunlight. If they are positioned in the shade, they will not grow well.


Another important thing to remember when planting your rhododendrons is to position the stems in a straight direction. If you put them at an angle, they will grow in a wavy fashion.

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How To Make Soil Acidic For Rhododendrons?

Rhododendron is one of the most beautiful flowering plants in the world. They are easy to grow, but you do need to know how to make soil acidic for rhododendrons. Acidic soil is needed for rhododendron to grow well and do their best.

To make the soil more acidic for rhododendrons, it is best to use acid in combination with other substances, such as blood meal or bone meal. In general, a good starting point is to have the pH of the soil pH at 5.8 or lower.

To create a well-drained garden area for rhododendrons, first, remove all weeds and then add a top dressing of lime to the garden bed, at least three weeks before planting. This helps to build the soil pH to a level that is more conducive to the growth of rhododendrons.

After adding lime to the soil, apply 3-4 tablespoons of blood meal per 1,000 square feet of soil, and let sit for six months before planting. Blood meal helps the plants absorb nutrients from the soil. After planting rhododendrons, sprinkle 2-3 teaspoons of bone meal on the soil every three weeks for the first two months.

After the first two months, begin fertilizing with 1-2 teaspoons of a liquid fertilizer containing 6-8-10 fish emulsions per 1,000 square feet of soil.

 How do you naturally acidify soil

How to measure soil acidity?

When measuring soil pH, you need to use a PH or potential of Hydrogen (pH) meter. A pH meter will give you your soil’s pH in 0.01 increments. The most accurate method for finding out your soil’s pH is to test samples from a wide area of your garden.

To make sure you get accurate readings from the soil samples, test the top 20 inches of the soil. The pH test is a very accurate indicator of soil acidity. It’s easy to do and requires no chemicals or equipment. A soil pH tester costs about $60 at local garden centers and nurseries.

The pH test measures the amount of base (alkali) cations in the soil. Calcium (Ca) is the main alkali metal cation found in soils. Many other metal cations contribute to the soil’s overall acidity, but they are much less abundant.

Calcium carbonate (CaCO3) is one of the most common substances in soils. It can also be dissolved in water to form calcium hydroxide (Ca(OH)2), a major component of many commercial fertilizers. This is how to make soil acidic for rhododendrons to ensure that your plant thrives.

What Are The Advantages and Disadvantages Of Using Acidic Soil?

Soils with a pH of less than 7 are acidic. While some plants prefer slightly alkaline soil to grow, others do well with acidic soil. Therefore, there are various advantages and disadvantages when using acidic soil. Listed below are the pros and cons of using this type of soil.


  • Acid soil will help rhododendrons develop new growth and flowers faster
  • Acidic soil is best for plants that grow in dry areas 
  •  Acidic soil helps reduce diseases that affect rhododendrons
  • The soil has sufficient nutrients for rhododendrons
  • It can absorb the water that comes out of the roots, so you don’t need to add as much water
  • Acidic soil is better for the Rhododendron plant roots
  • The acidity helps the plant store nutrients
  • The acidity makes the soil more porous, which is good for rhododendrons to thrive


  • Acidic soil can be a problem for other plants that are growing near your rhododendrons
  • It is important to monitor the salt levels in the soil
  • Knowing how to make soil acidic for rhododendrons is vital if you want your plant to reach its full potential.


The acidity helps to balance the soil and keep plants healthy. Acidic soils help rhododendrons thrive. Make sure to test the pH before digging up your rhododendron and treating it with acid. A pH test kit is usually available at your local garden store.

You can also use wood ash to acidify the soil, which is an easy process. If you don’t have access to wood ash, you can also use sulfur to increase the acidity in the soil. It’s a little trickier than using wood ash but can work just as well.

If you are growing rhododendrons indoors, you can also use the same technique, but if you have the space outdoors, you might need to apply a layer of mulch over it. Now that you know how to make soil acidic for rhododendrons, you can enjoy beautiful blooms! Click on the link for information on how to grow rhododendrons. 


How can I make my rhododendron soil more acidic?

To make your rhododendron soil more acidic, you can add lime to the soil. Lime is calcium hydroxide that breaks down many organic materials into carbon dioxide and water. These include leaves, stems, twigs, seeds, and animal manure. It also helps release nitrogen from organic matter to increase plant growth. Lime will acidify soil pH. Most rhododendrons are adapted to acidic soils, so if your soil is already too alkaline, you may need to lower it with lime.

How do you naturally acidify soil?

Natural acidification occurs when the ground is covered with vegetation and exposed to rain. As the rainwater percolates through the ground, it dissolves rocks and leaves their components, mainly carbonic acid, in solution. The process of naturally acidifying your soil will continue as long as the soil remains moist.

Can you use vinegar to make soil acidic?

Yes, you can use vinegar to make soil acidic. It breaks down the soil's natural ph level and makes it more acidic. 

What is a good fertilizer for rhododendrons?

A good fertilizer to use on rhododendrons would be Miracle-Gro as it is an all-purpose fertilizer. It is recommended to apply fertilizer when the soil temperatures are above 60 degrees and have adequate moisture.

Learn more about The Best Soil For Autoflowers

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