Changing Hydrangea Color: Expert Tips For Large Colorful Blooms

Did you know that you can change the color of your hydrangeas by simply adjusting the soil PH? Hydrangea Macrophylla (also referred to as Mop-head or Big-leaf Hydrangeas) are a gorgeous staple of the garden and offer head-turning flowers. There are not many flowers that can compete with the stunning shades of blue flowers or simply the size of their enormous blooms! However, it can be frustrating if you make an investment in this eye-catching shrub and don’t get the blooms in the color you had hoped for. The large blooms can vary from shades of blue, pink and purple. There are some tricks to how you can control and change the color of the blooms to your preference!  

Tip #1 Buy a Hardy Variety

The first tip in getting a hydrangea in the color you want is to buy a hardy variety for your zone. Make sure to plant them in a partial sun location or even a shady spot. Here are my Endless Summer Blue Hydrangeas covered with vibrant blue flowers, which we often see when we visit many New England towns. 

Tip #2 Hydrangeas Need Regular Watering 

My Endless Summer hydrangeas LOVE consistent moisture and will notify you when they are thirsty with their droopy and sad looking downward facing blooms. They shout out “I’m dying of thirst over here!”. Even though they are sometimes a little demanding, I cannot say enough about my Endless Summer Hydrangeas. They have proven themselves year after year by giving me blooms that I can rely on in my choice of color. Being a purple fan, I also really love Endless Summer “BloomStruck” which can vary from a dark shade of purple to a pale pink.

Tip #3 Adjusting Your Soils pH Level

The secret to getting the blooms in your favorite color(s) is adjusting your soils pH around the hydrangea plant. It is a simple garden task that I do every spring.

Soil pH is the real reason why you will find your hydrangea blue, purple, or pink. Soil pH ranges from 0-14 and it measures how acidic or alkaline your soil is. Soil that tests from 0-7 on the pH scale is acidic and soil that tests from 7 and above is alkaline. A pH of 7 is considered neutral. A very important note on this topic is that Soil pH is very important to your plant's health as the pH affects the availability of nutrients to plants! 

Soil pH in Hydrangea Terms 

Soil pH and Color

• Blue: Soil with a pH of 5.5 or lower
• Pink: Soil with a pH of 6.5 or higher
• Purple: Soil with a pH between 5.5 to 6

Soil pH Adjustment

• To make soil more acidic: add Aluminum Sulfate annually
•  To make soil more alkaline: add Garden Lime annually

Steps To Adjusting Color 

Spring time is perfect for amending soil. Soil amendments affect forming buds not flowers already in full bloom. So when spring hits it is a perfect time to put on your gloves, get out your Aluminum Sulfate OR Garden Lime, and a couple of gardening tools!

Step 1: Scatter 1/4-1/3 cup of the granules that you are applying around the drip line of your hydrangea (this is the area under the shrub that extends to the tip of the outermost branch).

Step 2: Using your hand tool or hoe lightly toss the granules under the soil (or mulch) about an inch deep.

Step 3: Thoroughly water the granules in and patiently wait for the hydrangea flowers to offer up the color of your choice!

Additional tip

You can test your soil with a Soil Test Kit to determine your soils pH.

It is important to set a yearly task on your calendar to adjust the soil pH. It needs to be adjusted every year or soil will revert to its natural state. It is a small gardening chore to do every spring as part of opening up and amending gardens. It will not only set up your gardens for success, but it will give you great satisfaction to see these beauties showing off in your favorite colors! Now that you know the trick in changing the colors of your hydrangeas, have fun and experiment with changing the hues of your hydrangea blooms!

You can also watch this video to learn how to change the color of your hydrangeas: