No-Fail Tips for Turning Hydrangeas Blue!

(photographer - unknown)

Everyone wants Blue Hydrangeas. The rarity of naturally blue flowers is an irresistible draw to gardeners. 

How to Turn Your Hydrangeas Blue?  Here are a few tips from Proven Winners:

Nikko Blue Hydrangea from Missouri Botanical garden

1. Be sure you’re working with the right kind of hydrangea.  You must have a Hydrangea macrophylla or H. serrata to have pink or blue flowers. 

(photographer -unknown)

2. Aluminum availability determines flower color. The availability of aluminum makes the flowers turn blue. Without aluminum the blooms will be pink. 

Soil pH must be low or acid (5.2-5.5) for the plant to absorb the aluminum.

from nely.bluehortensia

3. Color changes need time to take effect.  Consistent treatment is necessary to
 turn your hydrangeas blue:

  •  Plant your hydrangeas in a phosphorous-free medium, and use a phosphorus-free fertilizer with lots of potassium (i.e. 25-5-30).

  • Drench with aluminum sulfate immediately after planting. A solution of ½ oz (1 Tbsp) per gallon is a good start. Be sure the plants are well-watered before applying the aluminum sulfate as it can burn the roots. (important!!!) Drench again in 10-14 days.
  • Alternatively, you may apply a controlled-release form of aluminum sulfate. Products such as Blue-Knight® will release aluminum sulfate over a three month period. This is safer.

Some varieties shift to blue more easily than others. Here are NEW varieties which produce blue flowers more easily than others: 

(Cityline have tight sturdy stems and these maintenance free plants require no pruning for more flowers in the coming summer. Intense colors will "pop" in your garden. The flowers age quite nicely into fall as well.)

Cityline Berlin Hydrangea by Benkes Blog

 Cityline® Berlin
 Cityline® Mars
 Cityline® Venice
 Cityline® Rio
 Let’s Dance® Starlight*
 Let’s Dance® Rhapsody Blue*
 Let’s Dance® Diva!*
 Edgy™ Orbits
 Tuff Stuff™ *
 Tiny Tuff Stuff™ *

*Denotes reblooming varieties.


  1. Dear Jan the photo that you repinned from Beverly Russell is actually my photograph. I can attest to the fact that nothing ever has been added to the soil in this garden. They are the best and happiest of any blue hydrangeas I have ever seen-and I have no idea why. Best, Deborah

    1. Deborah - I am so sorry! and I have changed the caption to your name. And I have added your fabulous website there too - Love your work!

    2. Jan, not to worry-the attribution of pictures on Pinterest get muddled the more they get passed around. But I do appreciate your setting the record straight. The most amazing thing is the blue hydrangeas. They have never been treated with anything. Deborah

    3. My mother lived in the coastal mountains of norther Calif. and her Hydrangas were a beautiful blue. She said her soil was very acidity living among the Redwoods

  2. This is a wonderful tip about having blue hydrangeas. I finally planted a hydrangea, a small type (Paniculata I think) called Bombshell, so that type won't turn blue. Still, it is my only hydrangea and I wanted a smaller bush so I am happy with it.

  3. I particularly like the title of your blog Serenity in the Garden. your website is amazing and always bring me interesting informations and ideas to deal with thanks.

  4. I just discovered your site and I am thrilled with the serene kids and great gardening tips. Thanks

    1. That is pics not kids, lol.


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