Keeping Your Hydrangeas Blue - Southern Oregon. Spring is almost here in Southern Oregon, and that means my hydrangeas will need some tender loving care. I love blue hydrangeas. This year, I have taken some tips from Southern Oregon's Valley View Nursery on how to keep my hydrangeas blue.
Hydrangeas come in shades of blue, pink or white. White stays white but pink flowers can be made blue or blue flowers can be made pink by changing the acidity of the soil. In neutral to alkaline soil (over pH 7) the flower becomes pink (or even red), in a strong acid soil (below pH 5.5) the flower becomes blue.
Due to a lack of acidity the beautiful blue hydrangea may take a disappointing pinkish hue over time. Since the flower buds are formed on old wood the secret to maintaining or returning to an intense beautiful blue is application of Master Nursery Hydra Blue (aluminum sulfate) to acidify the soil. Two or three applications may be necessary. I am going to try this to keep my Southern Oregon hydrangeas blue.
