Root. In the computer world, root refers to the top-level directory of a file system. The word is derived from a tree root, since it represents the starting point of a hierarchical tree structure.
Use a fertilizer with high levels of phosphorus. Phosphorus helps to prevent aluminum from creeping into the system of the hydrangea. Choose a fertilizer close to the ratio of 25/10/10 (Phosphorus is the middle number).
Tips. 1  Lime or the aluminum sulfate tablet should be available at your local garden center. 2  Control over the color is easier for potted hydrangeas than for ground-planted plants. 3  Don't try manipulating white hydrangeas; you can't change them. 4  Changing a hydrangea from pink to blue is easier than changing it from blue to pink. Lime or the aluminum sulfate tablet should be available at your local garden center. 2  Control over the color is easier for potted hydrangeas than for ground-planted plants. 3  In particular, forcing pink hydrangeas is easier in potted form. 4  Don't try manipulating white hydrangeas; you can't change them.