Did you fall in love with a beautiful blue Hydrangea and plant it in the garden, only to have it bloom purple or pink the next year? There’s a fix for that! Acidify your soil using Aluminum Sulfate.
Understand that it is only Bigleaf Hydrangeas (Hydrangea macrophylla) that you can change and some hybrid varieties will not alter in color. But, if you started out with a blue Hydrangea, this little trick will help restore the color.
Aluminum Sulfate can be purchased from most garden centers. It is a fine white crystallized powder that I sprinkle around the base of my hydrangeas, water in and then mulch. Wear gloves while hand sprinkling the powder and rinse it off the Hydrangea’s leaves. Each fall and early spring (beginning of March) I spread a light application around my Hydrangeas and they reward me with gorgeous blue blooms.
This is not a one shot deal and don’t over do! One application may not do the trick and applying too much Aluminum Sulfate may be toxic to the plant. Aluminum Sulfate lowers the pH of the soil making it more acid. If you prefer, mix 1/4 cup of the Aluminum Sulfate powder to 1 gallon of water and water around the plant’s base.
After sprinkling the powder around your hydrangeas, water well and mulch. Adding pine needles, shredded leaves or pine mulch will also help acidify the soil over time.
And, when you are planting a blue Hydrangea, work peat moss right into the hole to get it off to a great start.
You can see for yourself that this soil amendment really works! Remember that the goal here is a more acid soil. Don’t spread any lime near your hydrangeas or you will reverse the process!
Now you know just how easy it is to keep those beautiful blue Hydrangeas blue! Hope you liked this garden tip! Make sure to pin it for later!