Continuing the vein of what I wrote you on using juice from red cabbage, that by adding an acid (lemon juice or vinegar), the color of the juice changes from blue (think of chicory, a dandelion relative) to pink.
Tangent to the chemistry of changing a blossom color into pink (or visa versa), a somewhat similar principal works in growing hydrangea plants, simply by altering the pH of the soil. Neutral to alkaline soils with pH 6.5 or higher produce pink flowers, blue flowers bloom in acidic soil of pH 5.5 or lower, and soil with pH between 5.5 and 6.5 produce purple flowers or a mixture of blue and pink flowers in the same plant.
Consider that it is much easier to change a hydrangea pink to blue (adding aluminum, copper, or zinc to the plant soil in a water solution throughout the growing season, taking care not to burn the roots) than blue to pink (the reverse, i.e. subtracting aluminum, copper, or zinc from the soil); one cannot change a white hydrangea at all. To ensure that the minerals are made available to the plant, it is important to note the pH level of the soil; for hydrangeas, the lower the pH, the bluer the flowers. Plants grown in soil with a pH over 7 may need to have iron added in some dosage as well.
How about that? The solution to pink blossoms may be in watering the plants! Maybe?
Iron nails, and aluminum, copper, or zinc placed on three sides of a hydrangea plant will give three different colored blooms in one plant. 100g (3.5 oz) of raw dandelion leaves contain .171 mg copper, 3.1 mg iron, and 0.41 mg zinc; the more, the merrier? Aluminum indeed does change hydrangea blossom color; however, adding the toxic aluminum produces blue—not pink—and, dandelion is an EDIBLE plant. Nicole, I’m so thankful that you want to go in a positively PINK direction!!!
Copper acts as a catalyst in the formation of hemoglobin; the copper-binding protein, ceruloplasmin, plays a major role to distribute iron throughout the body, especially to the brain. (People with dementia have inadequate ceruloplasmin levels.) Dandelion is a rich source of iron, a mineral essential for life. Zinc is a trace mineral required by over 100 enzymes that make DNA for cell replacement and protein synthesis from amino acids. A human body needs zinc to maintain proper levels of vitamin C; dandelions help supply this important element.