How to Make Hydrangeas Pink (Yes, They Can Change Color!)

It's easy to love hydrangeas for their big, beautiful blooms. However, these flowers are even more remarkable because certain hydrangea varieties can change between blue, purple, and pink. You might think the type of fertilizer you use controls the color, but it's more about soil pH, which measures how acidic or alkaline the earth in your garden is. So if you're wondering how to get pink hydrangeas, remember that the higher the pH, the more intense the rosy color of your hydrangeas. Here's how to ensure you get perfectly pink hydrangea flowers every year.

1. Choose the Right Hydrangea

Only the flowers of bigleaf hydrangea (Hydrangea macrophylla) and mountain hydrangea (H. serrata) can change color. Other types, like oakleaf hydrangeas (H. quercifolia) or smooth hydrangeas (H. arborescens), such as 'Annabelle', can't change their flower colors. They naturally bloom in white, cream, or dusty pink. These plants are just as full and beautiful, but if your goal is deep pink hydrangeas, make sure you're planting varieties that can turn that color.

Two popular bigleaf pink hydrangea varieties with gorgeous blooms include Let's Dance 'Big Band' ($24, Great Garden Plants) and Endless Summer 'Summer Crush'.

2. Measure Soil pH

Soil pH naturally ranges from 0 to 14, with 7.0 being neutral. Lower than 7.0 is acidic, and higher is alkaline. If you want pink hydrangea flowers, the pH needs to be on the alkaline side. Finding the pH of your soil is quick and easy to do with a soil test kit. A reading above 7.0 means that your hydrangeas should produce pink flowers without you having to do anything else. A reading between 6.0 and 7.0 usually results in purple to pink hydrangeas, and readings lower than 6.0 yield purple to blue flowers.

3. Increase Low Soil pH

The best way to increase the pH of your soil is to use garden lime made from crushed dolomitic limestone. Add the pellets to the soil when you plant your hydrangea. Or follow package directions to amend the soil around an established plant. Higher pH levels make aluminum in the soil less available to plants. This element makes the blue color appear in hydrangea blooms.

4. Don’t Forget to Fertilize

Soil amendments, such as garden lime, may change hydrangea flower colors, but they don't give the plants all the nutrients they need to thrive. Hydrangeas do best when fertilized in early spring as soon as leaves emerge.

If you're growing a reblooming variety like those from the Endless Summer series, add fertilizer again after the first flush of flowers in midsummer to encourage plants to produce another set of flowers. Don't feed your hydrangeas after July; it may stimulate tender new growth that's more sensitive to frost damage. Instead, use a slow-release, all-purpose fertilizer to give your plants a steady supply of nutrients over the growing season.

5. Practice Patience

Changing the pH of garden soil takes anywhere from 3 to 18 months. Continue adding garden lime for pink hydrangea flowers according to package directions until the desired color is reached. Maintaining the consistently pink hydrangea blossoms will require regular applications of garden lime, so it's a good idea to add it whenever you add fertilizer. Once flowers appear, they won't change color, so you'll have to wait until the following year to see a different color resulting from your efforts to modify soil pH.

6. Consider Containers

In yards with very acidic soil, it can be challenging to raise the pH enough to get pink hydrangea flowers and keep them up. It's easier to grow your bigleaf hydrangeas in containers in a good-quality potting mix, which usually won't have aluminum, so the flowers can't turn blue.