What makes hydrangeas turn purple

However, as Michael Dirr explains in his book Hydrangeas for American Gardens , the color is not determined by the pH, per se, but the amount of aluminum a plant can access in the soil — which is determined by pH and phosphorus levels. A lower pH allows aluminum to be soluble and absorbed by plants unless phosphorus is high , and the flowers tend to be blue. A higher pH locks up the aluminum and the flowers tend to be pink.

Shades of cream to green can also be seen when blooms first open, and tones can change as flowers age. Tip: Find out your soil's pH by using a 3-in-1 soil tester. Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil.

The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum. Hydrangeas are beautiful flowers. They accentuate the landscape of any home very well. They are unique because most of these gorgeous flowers can change colors. This gives us the opportunity to try and pick the color of our hydrangea blooms that we have planted in our yard. There are approximately 20 different types of Hydrangeas.

Many of which have their own specific colors usually beige, white, yellow, pink or blue. Each type may have different colors within their subcategory but, they will each only bloom with one color flower. However, the Hydrangea Macrophylla lacecap, mopheads and bigleaf can change the color of their flowers.

It is because these amazing flowers get their colors solely from the pH levels in the soil they are growing in.

This means they can bloom pink, then blue, and then back to pink. Some of them naturally bloom in blues just be sure to check the tag. It may take a long time for your flowers to change color, since hydrangeas absorb nutrients slowly. Add the lyme or the aluminum sulfur once a year during the fall so your plants can absorb them over the winter and change color before spring. It can take 1 to 2 growing seasons for your hydrangeas to change color. Test your soil pH again to see if it has changed.

If your soil pH is still too acidic or basic, keep adding your supplements. If your soil pH has reached a neutral area between 5. Blue hydrangeas are harder to change to purple since they are already on the blue area of the color wheel. Include your email address to get a message when this question is answered. Take it slow so your hydrangeas stay healthy. Helpful 0 Not Helpful 0. Submit a Tip All tip submissions are carefully reviewed before being published.

Always wear gloves when handling garden lyme to avoid skin irritation. Helpful 0 Not Helpful 1. Related wikiHows How to. How to. More References 2. About This Article. Co-authored by:. Co-authors: 8. Updated: September 28, Categories: Gardening. Thanks to all authors for creating a page that has been read 4, times. Did this article help you? They thrive in U.

S Department of Agriculture plant hardiness zones 6 through 9, and the long-lasting flowers typically come in rich blue and pink hues. Bigleafs come in two different varieties: mopheads and lacecaps. Each produce blossom clusters that unite showy, sterile flowers with short, fertile flowers. The mophead variety is a ball of showy florets, while the lacecap form offers flattened disks of the small, fertile florets ringed with a fringe of showy florets.

Both types of bigleaf hydrangea come in shades of pink and blue. Some are deep and rich, while others are pastel. However, you usually don't have to accept the color you get.

The color and its intensity depend on the acidity of the soil and the amount of aluminum in the soil. Many gardeners find this color change enchanting, but it is more chemistry than magic.