How to change the color of Hydrangea plants


Change the color of your Hydrangeas from pink to blue or vice versa.

Did you know the color of your Hydrangeas can vary depending on soil PH and certain elements in soil which you can manipulate to get your desired color.

PH is a scale from 1 to 14 with 7 been neutral, if your soil is less than 7 its said to be acidic and if its higher its Alkaline.

Turn Hydrangeas Blue


For Hydrangeas to turn blue 2 things are needed.

  • The soil needs to be acidic (around 5.2-5.5 is good)
  • Aluminium need to be present in soil (its what turns them Blue)

Some elements can only be absorbed by a plant if the PH is correct so to turn the Hydrangeas blue the plants needs to take up Aluminium and it requires an acidic soil to do this.

Aluminium is a very common element and makes up about 8% of the earth’s crust.

To lower your PH or turn the soil acidic you can do any of the following:

  • Add organic material like compost, manures, mulch etc.
  • Add Iron sulphate
  • Add Aluminium sulphate (which also helps if soil is aluminium deficient)
  • Add Sulphur

Turn Hydrangeas Pink


To turn your Hydrangeas from blue to pink we need to block the uptake of Aluminium by the plant. Increasing the PH of the soil to around Neutral will normally do the job. Increase to PH by adding Agricultural Lime a few times a year.


About Warren Downes

Warren has been commercially growing plants for over 26 years in his wholesale nursery, Downes Wholesale Nursery and in that time has developed a wealth of knowledge of plant growth and the horticulture industry.

Warren is also a keen creator and educator on YouTube check out his Woodworking channel.



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