The Blue Bloomers Among Hydrangeas

Hydrangeas come in many shapes and colors. From blue to white to pink and purple, the selection is vast. It can be difficult to choose the right one. Which plant with which colored blooms is the best match?

If you've decided on blue, it can be disappointing to find that the garden center you chose no longer has any blue hydrangeas. However, this disappointment doesn't have to last long, as certain varieties of hydrangeas can be turned blue!

Blue hydrangeas are particularly elegant. This is probably because the color blue is still associated with royalty – think "blue bloods." And indeed, blue hydrangeas are very popular. However, as popular as they are, they are often sold out quickly. A pink hydrangea, though, can come to the rescue. And even though it is pink, the flowers of the plant can shine in a royal blue.

To turn pink hydrangeas blue, several factors need to align. The primary cause of the blue color in the flowers is a specific mineral – alum. Alum is an aluminum salt that contains not only aluminum ions but also sulfate, potassium, and ammonium. However, it is the aluminum ions that are crucial for the blue color of the blooms. Additionally, the plant requires an acidic humus soil with a pH below 5.0. To change a pink hydrangea into blue, alum is mixed with the watering water. Alum can be found at pharmacies or as a combination with hydrangea fertilizer in specialized stores. Pure alum should be administered in a ratio of 3 grams per liter of water.

Unfortunately, not every farmer’s hydrangea is suitable for turning its blooms blue. While a pale pink hydrangea may seem like a good start, alum can't work miracles. However, the most popular variety, "Endless Summer," is particularly receptive to this process. While it already looks beautiful naturally, blue flowers make the hydrangea even more elegant.