Hydrangeas: Changing Colors

Hydrangeas are well known for their variable coloring. However, not all hydrangea blooms will change colors. This ability is specific to certain varieties of hydrangeas (mostly H. macrophylla or H. serrata species). Some hybrids will not change coloring and white hydrangeas will always be white.

The change in color is determined by how much aluminum the plant can absorb. Without going deep into the science, it’s related to the soil pH level. By adjusting your soil pH, your hydrangea blooms can go from pink to blue and any color in-between.

Blue Hydrangea

Blue - More Acidic

A more acidic soil (pH 5.0 – 5.5) causes hydrangeas to bloom blue. To lower the pH of your soil use a sulfur product. Youngs carries safe, long lasting products to accomplish this.

With Youngs organic products you should begin application in early spring and re-apply every 60 days until you reach your desired pH level and you get the shade of blue that you’re after.

Alternatively, with mixed results, some people use things like coffee grounds or organic compost to make the soil more acidic.

Pink Hydrangea

Pink - More Alkaline

A more alkaline soil (pH 6.0 – 6.5) encourages pink blooms. If you’re trying to go more pink, you’ll want use a lime product. Youngs offers several easy to use options that act quickly.

Apply Garden Lime in early Spring, Late Spring and Fall.

Some people also use crushed eggshells, which break down slowly to reduce the acidity.

Purple Hydrangea Coloring

Hydrangea Color Changing Tips

  • Try growing hydrangeas in containers! New compact hydrangeas are great in containers and it’s much easier to control the coloring.
  • It’s a lot easier to change a bloom from pink to blue than it is to go from blue to pink (pink blooms are achieved by taking aluminum away from the hydrangeas).
  • Feeding your hydrangeas for a healthier plant can help produce more intensely colored blooms.
  • Water your plants consistently, especially during the heat of the summer when they are prone to wilting.
  • Nearby concrete will leach lime into the soil. If you plant hydrangeas near a driveway or cement patio it will be more difficult to get blue flowers.
  • When you are amending the soil around your hydrangeas, keep in mind the other plants around. Other plants may not be able to take the soil pH changes as well.
Adjust Soil pH for Hydrangea Color