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How to change the color of your garden hydrangeas

Updated on March 6, 2013

Hydrangeas are a very unique flower as you can actually change the color of their blooms. With a few changes in fertilizer you can change your pink flowers blue or your blue flowers pink. You can also deepen the colors with other fertilizers. The white hydrangea however does not fall in the color-changing category and will always be white. Sometimes as the bush ages it can turn the edges of the flowers pink.

Pink to Blue

Changing the blooms from pink to blue is fairly easy, you just have to add a little aluminum to the soil. This is done by treating the area the plants are in with aluminum sulfate, about a tablespoon per gallon. This can be purchased at any feed and seed store that carries chemicals. Then regularly fertilize with one high in pottasium, such as (25/5/30). To enhance the blue of an already blue flower fertilize with powdered pottasium or a fertilizer with a high 3rd number.

For an organic approach, composte full of organic matter, coffee grounds and worm casings is high in aluminum and lower the pH over time. A pH of 5.2-5.5 is optimal.

Blue to Pink

Turning your blue blooms pink are a little harder to do because you have to remove the aluminum, or raise the pH of the soil to achieve the coveted pink blooms. The chemical way is to use dolomitic lime and fertilize regularly with a fertilizer high in phosphorus and nitrogen. Make sure the middle number is high for phosphorus or a powdered variety is available. Phosphorus prevents the plants from absorbing aluminum and keeping the color you desire. A pH of 6.0-6.2 is optimal, much higher the plants can get iron defficiency.

A more natural way can be to heavy mulch with pine bark or mulch. The nitrogen will leach out of the bark, but it will take time and a large amount of dirt would have to be replaced to achieve a color change. There are also natural sources of phosphorus to be found.

Organic Phosphorus


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    • kaiyan717 profile image

      kaiyan717 5 years ago from West Virginia

      Hydrangeas need shade for sure. A way to keep deer away from any plant is to spinkle red pepper on the plants, works for all animals, put a little fire in their nose to stay away. Clay soil just has to be replaced with some composte and top soil so you can start to grow in your yard. Good luck Rosie!

    • kaiyan717 profile image

      kaiyan717 5 years ago from West Virginia

      Random-I am not sure if other plants do this, I have not came across them yet, except the old food coloring trick.

    • Rosie writes profile image

      Rosie writes 5 years ago from Virginia

      I've always wondered exactly how to do this - thanks for the straight forward information. I love Hydrangeas, but I can't seem to get them to grow, with the deer, the heat, and the clay soil where I live. I'm still trying though; I would love to have a few of the plants in my yard!

    • RandombyBabbles profile image

      RandombyBabbles 5 years ago from Houston,TX

      Very Cool! I didn't know this could be done.Thanks. with what other flowers can similar methods be used?

    • kaiyan717 profile image

      kaiyan717 5 years ago from West Virginia

      What a great way to keep the pH right for her flowers. Great information always comes from our previous generations.

    • moonlake profile image

      moonlake 5 years ago from America

      My grandmother use to bury tin cans under her hydrangeas. I was just a kid when I remember her doing that. Lots of good information. I love hydrangeas. Voted Up.