Hydrangeas are a very beautiful plant and one reason they are so popular in gardens is that they have the unique ability to change a variety of colors. The color of the flowers that bloom on these bushy plants can take on many shades of red, blue, pink, purple, white, and more.
Many hydrangeas will go through a slight color change when transplanted due to adjusting to their new soil when you first bring them home. But if you really want to shake things up, this simple little soil hack will make your Hydrangea change color! This will only work for the blue or pink varieties (white blooms cannot be changed to any other color). However, you cannot change the intensity of the color; that is more dependent on the environment or weather.
The first thing you need to do is test the pH of your soil. Acidic soil (lower pH) will yield blue flowers and alkaline (higher pH) will give you pink flowers. You can buy a soil test kit at your local garden center to determine the pH of the soil, but here is a quick and simple way to figure out your soil’s pH without such kit. Once you know the general pH of your soil, you can adjust it to get pink or blue hydrangea blooms.
Turn pink blooms blue
If your hydrangeas are pink (because your soil is alkaline) and you want them to be blue, you need to make the soil acidic by increasing the presence of aluminum. You can achieve this by adding amendments to you your soil like pine needles, compost, coffee grounds, and aluminum sulfate that help make the soil acidic over time. Keep in mind that changing the pH of your soil is a gradual process and will not result in deep blue blooms overnight. It can take up to a year for the color change to happen.
If your soil is naturally alkaline, you’ll have to add an aluminum source throughout the growing season to keep them blue. If you are using aluminum sulfate, you will need to add 4 tablespoons of aluminum sulfate to a gallon of water, and drench around the base of the plant every 2 to 4 weeks.
Turn blue blooms pink
To change hydrangea blooms from blue to pink, you need to remove the aluminum from the soil. The only way to do this is to add garden lime to soil to help raise the pH. Sprinkle 3 to 4 cups of garden lime around the base of the plant. Again, you will have to add the lime every 3 to 4 weeks throughout the growing season to keep the blooms pink.