How to Make Hydrangeas Blue: A Comprehensive Guide

To make hydrangeas blue, you need to adjust the soil ph level to become more acidic. One way to do this is by adding aluminum sulfate to the soil.

This will change the hydrangeas’ flower color from pink to blue. Hydrangeas are one of the most beloved and beautiful garden plants, known for their big, showy blooms and vibrant colors. But did you know that you can actually change the color of the flowers? While many hydrangeas naturally bloom in shades of pink, white, or purple, some varieties can be coaxed into producing blue flowers. If you’re curious about how to make hydrangeas blue, there are a few simple steps you can take. In this article, we’ll explore what causes hydrangeas to change color, what you need to do to adjust the ph of your soil, and some tips for taking care of your blue hydrangeas once they start blooming. So let’s get started!

How to Make Hydrangeas Blue: A Comprehensive Guide


Understanding The Science Behind Changing Hydrangea Color

If you love hydrangeas, you may have wondered how to make their colors more vibrant and bright, especially if you want to create a blue hue. The good news is that it’s entirely possible! In this blog post, we will explain the science behind changing hydrangea colors, specifically, how to make hydrangeas blue.

Explanation Of Ph Levels And Their Effect On Flower Color

To understand how to make hydrangeas blue, it’s important to know that the ph level of the soil has a significant impact on the color of a hydrangea’s blooms.

  • Soils with a ph level above 7. 0 are alkaline (basic), while soils with a ph level below 7. 0 are acidic.
  • The availability of aluminum, which is present in the soil, is strongly influenced by the soil’s ph level.
  • At low ph levels, aluminum is more soluble in water and, therefore, more available to hydrangeas.
  • At high ph levels, aluminum becomes less available to hydrangeas.
  • In general, hydrangeas with blue flowers grow best in acidic soil with a ph level between 5. 2 and 5. 5.

Discussion Of Aluminum And Its Role In Creating Blue Hydrangeas

When it comes to making hydrangeas blue, aluminum plays a crucial role.

  • Aluminum is a naturally occurring substance in soil and is present in varying amounts.
  • In the right conditions, when aluminum is present in hydrangea petals along with other naturally occurring substances, it can create a blue hue.
  • If there is not enough aluminum in the soil, the hydrangea flowers will appear pink or white.
  • To make hydrangeas blue, aluminum sulfate is sometimes added to the soil in small quantities to lower its ph level and increase the availability of aluminum.
You May Also Like:  Where to Buy Orchids? Find the Perfect Orchid Supplier Today!

Relationship Between Soil Ph And Aluminum Availability For Hydrangeas

The ph level of the soil and aluminum availability are closely related, and getting them right is key to producing blue hydrangeas.

  • Soil ph levels affect the solubility of aluminum in the soil.
  • When the soil ph level is too high, the solubility of aluminum decreases, and there is less available aluminum to be taken up by the hydrangeas.
  • When the soil ph level is too low, the available aluminum can become toxic to the plant.
  • The ideal ph level for growing blue hydrangeas is between 5. 2 and 5. 5, which allows for the optimal amount of aluminum availability for the plant to create blue flowers.

If you want to make your hydrangeas blue, it’s important to understand the relationship between soil ph, aluminum, and their role in creating blue hydrangeas. By making small adjustments to the soil and using aluminum sulfate, you can create the perfect conditions for your hydrangeas to produce vibrant blue blooms.

Testing Your Soil Ph

Importance Of Testing Soil Ph Before Attempting To Change Hydrangea Color

When it comes to changing the color of hydrangeas, many factors come into play, from the variety of the plant to the weather conditions. However, the first step in changing the color of your hydrangeas is to test the soil ph.

  • The ph level of the soil determines the availability of nutrients to the plant and affects its growth and development.
  • Different hydrangea varieties require different soil ph levels to produce the desired flower color. Testing the soil ph will help determine the amendments needed to reach the desired ph level.
  • Changing the soil ph significantly can take time, so testing your soil is a crucial way to avoid wasting time and effort on the wrong amendments.

Explanation Of The Different Methods For Testing Soil Ph

There are several methods for testing soil ph, each with their pros and cons.

  • Soil testing kits: these kits are available at gardening stores and are easy to use. It involves taking a soil sample, mixing it with distilled water, and adding a testing solution. The solution changes color based on the ph level of the soil, indicating acidic or alkaline conditions.
  • Ph meters: these are electronic devices that determine the ph level of the soil by measuring electrical currents in the soil. They are more expensive than soil testing kits but are more accurate and can test the ph of the soil in real-time.
  • Laboratory testing: this method involves sending a soil sample to a laboratory for analysis. It’s the most accurate method but can be expensive and time-consuming.

Tips For Interpreting Your Soil Test Results

Interpreting soil test results can be overwhelming, but it’s crucial to ensure that you understand the results before taking action.

You May Also Like:  How to Grow Onions in Florida? A Comprehensive Guide
  • Look for the soil ph level and the specific amendments needed to reach the desired ph level.
  • Check for the nutrient levels needed for the hydrangea variety you’re growing. For example, if the soil is lacking in phosphorus, adding a phosphorus-rich fertilizer will help promote the plant’s growth and development.
  • Keep in mind that soil amendments take time to break down and create an impact. Don’t expect immediate changes to the plant’s color after making amendments.

By following these guidelines, you’ll be on your way to successfully changing the color of your hydrangeas by adjusting the soil ph level. Remember to test your soil every few years to ensure that the soil ph level remains within the desired range for your hydrangea variety.

Step by step: How to turn Hydrangea Flowers Blue

Adjusting Soil Ph To Make Hydrangeas Blue

Blue hydrangeas are a sight to behold, creating a lovely pop of color in any garden. While the natural colors of hydrangeas range from pink to purple and everything in between, it’s possible to change the hue to a stunning blue shade.

The trick is to adjust the soil ph, making it more acidic. Here’s how to make hydrangeas blue using soil amendments.

Using Soil Amendments To Lower Ph And Make Soil More Acidic

One of the most effective ways to change the acidity of your soil is by using amendments.

  • sulfur: sulfur is a popular soil amendment for lowering ph levels, which helps hydrangeas attain a blue shade. It’s best to use elemental sulfur, and the amount required depends on the ph level of your soil. Generally, 1/2 pound of sulfur per 100 square feet should bring the ph down by 1. 0 point. For optimal results, mix the sulfur into the soil before planting.
  • peat moss: peat moss is another soil amendment that can help increase soil acidity. Similar to sulfur, the amount required varies based on your soil’s ph level. Peat moss also improves soil drainage and holds moisture, making it a beneficial option for hydrangeas. Just mix a layer of peat moss into the soil before planting to get the best results.
  • pine needles: pine needles are a natural way to increase acidity in your soil. As the needles decompose, they release acidic compounds that lower ph levels. Simply add a layer of pine needles around the base of hydrangeas and allow them to decompose naturally over time.

Discussion Of Various Acidifying Amendments

When it comes to acidifying soil, there are a few different amendments to consider.

  • sulfur: as mentioned earlier, sulfur is a powerful amendment that can lower ph levels. It’s important to use the correct type of sulfur, which releases the right amounts of sulfuric acid required to make soil more acidic.
  • peat moss: peat moss is an organic matter that is rich in acidity and can provide long-lasting benefits to soil. It also breaks down slowly, making it an efficient amendment.
  • aluminum sulfate: aluminum sulfate is another popular amendment that lowers soil ph levels. It also adds aluminum to the soil, which helps hydrangeas absorb more of the blue pigment.
  • iron sulfate: iron sulfate is an excellent amendment that provides iron to the soil while lowering ph levels. It is slow-release, making it an ideal option for long term soil health.
You May Also Like:  How to Keep Limelight Hydrangea Small?

Tips For Using Soil Amendments Safely And Effectively

While soil amendments can be very beneficial, it’s important to use them correctly to avoid any negative impacts on the soil.

  • Before using any amendments, test the soil ph level using a ph testing kit. This will help determine the correct amount of amendment required.
  • It’s recommended to wear gloves while working with soil amendments to prevent skin irritation.
  • Always follow the recommended dosage listed on the package and avoid overusing amendments as it can be hard to reverse.
  • Remember, it can take time for amendments to show their effectiveness, so be patient.

Using soil amendments is a safe and effective way to lower ph levels and make soil more acidic, ultimately leading to stunning blue hydrangeas. With the right amendments and proper application, you’ll enjoy your beautiful blue blooms year after year.

Applying Aluminum Sulfate To Make Hydrangeas Blue

Explanation Of How Aluminum Sulfate Works To Create Blue Hydrangeas

Aluminum sulfate helps to lower the ph level of the soil, allowing hydrangeas to absorb more aluminum, which produces a blue color. The aluminum ions react with the natural pigments in the hydrangea petals, causing them to turn blue.

  • It is most effective on hydrangeas with white or light-colored flowers
  • The results depend on the ph level of the soil and the amount of aluminum sulfate used
  • Soil that is naturally high in aluminum can produce blue hydrangeas without the need for aluminum sulfate

Discussing The Pros And Cons Of Using Aluminum Sulfate

Before applying aluminum sulfate to your hydrangeas, consider the advantages and disadvantages:


  • It can transform pink or white hydrangeas into stunning blue blooms
  • It is an affordable and readily available solution for changing hydrangea colors
  • It is an effective solution for combating soil alkalinity


  • Overuse of aluminum sulfate can damage plants, burn roots and stunt their growth
  • It can be harmful to other plants in the garden or cause soil contamination
  • It requires careful application and monitoring of soil ph levels

Guidelines For Applying Aluminum Sulfate Safely And Effectively

Here are some guidelines to follow when using aluminum sulfate to achieve blue hydrangeas:

  • Apply in the spring before the hydrangeas bloom
  • Use the appropriate amount based on soil ph and desired color change
  • Work the aluminum sulfate evenly into the soil around the drip line of the plant
  • Water thoroughly after application to help distribute the aluminum sulfate evenly
  • Reapply annually as needed to maintain color

By following these guidelines, you can enjoy vibrant blue hydrangeas in your garden. Remember to use aluminum sulfate safely and effectively to avoid damaging your plants or soil.


After going through this comprehensive guide, we can confidently say that making hydrangeas blue is not rocket science. With the right adjustments, such as altering the soil’s ph levels, adding aluminum sulfate, and using fertilizers containing high levels of phosphorus, you can easily transform your pink hydrangeas to the beautiful blue color you desire.

However, it is crucial to remember that hydrangeas require proper care for growth and flowering, including regular pruning, deep watering, and avoiding direct sunlight exposure. Additionally, it’s essential to maintain an optimal soil ph level for hydrangeas to continue flourishing.

So get green-fingered and give these tricks a try to add a refreshing pop of blue to your garden. With a little bit of effort and patience, you’ll be amazed at how gorgeous your hydrangeas will look!