It’s no secret that you can change the color of your hydrangeas. White stays white so when making a purchase decide first what colors are important to you. The other colors (blue and pink) are changeable on any plant.
The pH in your garden’s soil determines the color, so if your soil is alkaline, your hydrangea flowers will be pink. Acidic soil will turn them blue. Use a simple pH test kit from your garden center if you want to keep the flowers a certain color before planting them.
I didn’t do a soil test because I don’t really care whether my hydrangeas’ blooms are either pink or blue. And, it’s a good thing because I have every shade from pink to purple to blue on my two plants and love it. Rocks and minerals also affect the pH of soil. Some blooms in my yard seem to reflect the color of the river pebbles I have placed around the plants.