Colors in Bloom

To walk among hydrangeas is to walk in the midst of a bouquet of biological and biochemical fascination. As one of today’s most popular ornamental flowers, with its opulent, globe-like blooms, the hydrangea is steeped in folklore, tradition, and, surprisingly, science–as the flowerheads possess a unique ability to change color, resulting in a kaleidoscope that ranges from pink to blue to lavender and violet.

 

HISTORY OF HYDRANGEA

The name “hydrangea” stems from the Ancient Greek words “hydro” (meaning water) and “angeion” (meaning pitcher), as it was thought that the petals–which are in fact sterile sepals surrounding the fertile part of the plant–resembled pitchers used for carrying water.

 

 

Throughout history, the colorful hydrangea has found its place among intriguing international lore. It is said in Japanese legend that an emperor once presented a bouquet of blue hydrangeas to the family of a girl he loved–a gift of heartfelt emotion and gratitude to demonstrate how much he cared for the maiden. Today, in some Asian cultures, to gift hydrangeas still means that you consider the recipient to be as important to you as “the beat of your own heart.”

 

While hydrangeas have been cultivated in China and Japan for thousands of years, the flower’s presence didn’t appear in Europe until 1775 when Swedish naturalist Carl Peter Thunberg carried five plants back with him on his return trip from Asia. The plant then quickly spread across gardens throughout the Northern Hemisphere.

 

FLOWER POWER

Currently, there are known to be around 70 species of hydrangea, in enough colors, sizes, and cultivars to please any gardener’s palette. Blooms vary in appearance–from the traditional snowball shape, to the delicate lace-cap, or the eye-catching cone-shape. For plant type, there are shrub hydrangeas, mop-leaf hydrangeas, hydrangea trees, and even climbing hydrangeas.

 

Deborah Silver, landscape designer and author of Dirt Simple, says that hydrangeas are easy to grow but can be difficult to plan in a landscape. Silver likens the hydrangea to “big, growing show-offs that don’t naturally play well with neighboring plants.” Silver notes that a single Limelight hydrangea can grow seven feet tall, and seven feet wide, and even the smaller growing cultivars have giant flowers. As such, they can become what she calls, “the elephant in the room, impossible to ignore.” Says Silver, “It takes some thought to integrate them into a garden, or a landscape. I favor planting rows of them, as opposed to a single plant. They want to be the star of the summer garden, so why not let them show off?”

 

Whether it’s the snowiness of the Annabelle or the perfect blue of the ever-popular Endless Summer, hydrangeas add showstopping power, not only in terms of volume but also in color. Beyond some of the more recognizable hues, varieties like Pistachio, Summer Crush, Strawberry Sundae, Lime Punch and Gin and Tonic–to name just a very few–have resulted from experiments in soil science.

 

With petals being more akin to a chem lab’s litmus paper, hydrangeas change colors in a very unusual way. Eighteenth-century gardeners were the first to notice this and experimented with the plant by burying rusty nails and pouring tea around the soil.

 

While the common rationale is that alkaline or acidic soil are what contribute to the color of hydrangeas, Henry Schreiber, retired emeritus professor of chemistry at Virginia Military Institute, and noted lecturer on experimental color changes in the hydrangea, remarks that there is really no need for a soil test prior to experimenting with color changes.

 

“Red inflorescences (blooms) on the shrub typically indicate you have basic soil,” says Schreiber, “whereas blue inflorescences typically indicate acidic soil. To change the blue inflorescences to red, sprinkle lime around the plant to change the pH of the soil to basic. On the other hand, to change red to blue, sprinkle aluminum sulfate (commercially available at most garden stores) around the shrub.” One caution, says Schreiber: “Be patient! It may take one or two growing seasons for the change to occur.”