nikko blue hydrangeas
I have nikko blue hydrangea 8 yrs. old. the 1st yr. they were blue. Now they are pink and lavender and have been since. I feed them acidic fertilizer. I have talked with the nursery man and he told me my water is probably neutral. Is there anything now this fall I can do to help them to come back to blue. I cannot change the ph of the water. Pls. help if you can and many, many Thanks.
Certified GKH Gardening Expert
It can be difficult to get soil down to a low enough (acidic) pH to get hydrangeas to really turn blue. Aluminum is also needed in the soil for the plant to create the blue color. Having a soil pH test done can show you how close you are to the necessary pH of 5.2-5.5.
Aluminum sulfate can help with both the pH and the aluminum requirement: