Every summer, Portugal's Azores islands, an archipelago in the mid-Atlantic Ocean, become awash in pillowy, colorful hydrangeas. The bushes, which bloom in shades of blue, pink, purple and white, have become a symbol for the region — and a hit on Instagram.

Hydrangeas are by far the most recognized plant of the Azores islands.
Hydrangeas are by far the most recognized plant of the Azores islands. (Photo: unukorno/Flickr)

There are nine volcanic islands in the Azores spread over about 370 miles. One island, Faial Island, is also known as Blue Island because of the abundance of gorgeous hydrangeas that line the roads and accent the landscape.

The soil on this island is acidic with a pH value of 5.5 to 5.2, and it's high in aluminum — both of which make the flowers extra blue. (The pH scale goes from 0 to 14, with 7 being neutral. Acid soils have a pH of 6.5 or less, and alkaline soils are 7.5 or more. )

Hydrangeas that grow in less acidic soil with less aluminum content will bloom in shades of pink, purple or white. A single garden may produce bushes with multiple colors as the soil qualities can differ within even a small area.

Pillowy pale blue and white hydrangea set against equally pillowy clouds on Faial Island in the Azores.
Pillowy pale blue and white hydrangea set against equally pillowy clouds on Faial Island in the Azores. (Photo: Guillaume Baviere/Flickr)

There's a dark reason behind Faial Island's extra-fertile soil. A volcanic eruption in 1957 lasted 13 months, burying hundreds of homes and entire villages with lava and displacing thousands of residents. The lava oozed into the ocean and cooled, creating another mile or so of coast line and incredibly fertile soil.

Purple hydrangeas in the Azores
Purple hydrangeas in the Azores (Photo: HibaHaba/Flickr)

Each of the towns holds some responsibility for taking care of the beautiful plants, whether pruning or planting. It's illegal to pick hydrangeas from public spaces like parks or the countryside. But if you live in the Azores, you probably don't need to pick them anyway. Nearly every property is adorned with at least one.

These gorgeous blue hydrangea on Flores Island look even more lovely against the deeper blue of the Atlantic Ocean.
These gorgeous blue hydrangea on Flores Island look even more lovely against the deeper blue of the Atlantic Ocean. (Photo: unukorno/Flickr)

The Azores, with a population of about 250,000, are known for their nature attractions. Besides the beautiful blue hydrangeas, there are blue-green lakes, rolling green hills, and on the island of Terceira you'll find lilacs and other purple wildflowers in bloom. No wonder it's otherwise known as the Lilac Island.

Multi-colored hydrangea and other lush greenery on the Azores.
Multi-colored hydrangea and other lush greenery on the Azores. (Photo: Martin Talbot/Wikimedia Commons)

While hydrangeas aren't native to the Azores, historians believe the plant arrived in the U.S. courtesy of immigrants from the Azores. In the mid-1900s, nearly a quarter of a million Azoreans (many of them fishermen) came to U.S. cities in Rhode Island and southeastern Massachusetts seeking better living conditions. Today, if you visit The Hamptons, Martha’s Vineyard or Nantucket you'll likely see stunning hydrangeas in the immaculate properties and gardens there.

Beautiful blue and white hydrangeas on the Azores' Sao Miguel Island.
Beautiful blue and white hydrangeas on the Azores' Sao Miguel Island. (Photo: Abspires40/Flickr)

Angela Nelson ( @bostonangela ) is an exhausted mom of two young daughters and two old cats, and a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide.