The surprising genetic reason why cherry blossoms bloom at the same time

One cherry tree blossom is a quiet marvel of spring. Thousands of the cotton-candy pink flowers are a transcendent spectacle.

Every spring, thousands of cherry trees simultaneously bloom, transforming Washington, D.C.’s rigid marble landscape into a flushing fairyland. The U.S. Capitol’s columns soften with pastel hues, while identical pink petals frame the Washington Monument and Tidal Basin.

“If you've ever been down to peak bloom and seen 1,700 cherry trees around the Tidal Basin all in bloom at once, you know that is a sight to see,” says Mike Litterst, chief communications officer for the National Mall and Memorial Parks. “It is one of those sites, like the Grand Canyon, that defies description.”

The synchronized dance is no coincidence. For centuries, arborists have cloned cherry trees for this harmonious display, ensuring that they grow and bloom in the same way.

But it also creates a hidden vulnerability: a single disease or pest infestation could wipe out the entire population, threatening the scene that draws over a million visitors to the nation’s capital each spring.

‘Essentially one tree’

In 1912, Japan famously gifted more than 3,000 cherry trees to Washington, D.C., as a symbol of friendship and goodwill. The delivery contained 12 varieties of cherry trees, but most were the Somei Yoshino (Prunus × yedoensis) seen around D.C.’s Tidal Basin today.

(How cherry blossoms came to the United States.)

Yoshinos were produced some 200 or 300 years ago, known for the striking pinkish white flowers and faint almond fragrance. They are a hybrid of two other cherry trees and because of their beauty, horticulturists have continued to clone the tree for centuries. 

Every year, Oregon-based nursery J. Frank Schmidt & Son Company harvests and ships more than 1.5 million trees across North America—including many Yoshino cherry trees to the East Coast. 

Nurseries clone trees through two main techniques, says Guy Meacham, new plant development manager at J. Frank Schmidt & Son. One method called grafting connects plant material from one tree to the root system of another. The other increasingly common method is through softwood cuttings, where a twig is cut from a tree, grown in a controlled environment with hormones, and produces new roots on its own.

“It's just a continual process of cloning from the original tree thousands and thousands of times,” says Meacham. “All Yoshinos that have been clonally propagated since that original one are identical to that one.”

In fact, Japanese researchers analyzed the genomes of 46 Yoshino cherry trees—including one from Washington, D.C., gifted in 1912—and showed they belonged to the same clone lineage. Some showed small mutations accumulated over time, so they weren’t exact copies, but they had the same two parental genomes.

“The disadvantage is you do have thousands of trees that are nearly identical. They're essentially one tree,” says Meacham. “If you were to get a pest or disease that your clone was particularly susceptible to, it would be more vulnerable than if you had seedlings.”

Battling a blight

Cherry trees have faced many threats from pests to diseases over the years. In 1910, Japan initially gifted D.C. 2,000 cherry trees, but the trees were infested with insects and nematodes diseased; the trees burned. Cherry trees have also historically suffered from fungal and bacterial diseases, such as “witches’ broom” or cherry leaf spot. which weakens the tree and causes flower or leaf failure if untreated. In 1945, cherry leaf spot disease caused early defoliation and killed more than 25,000 sweet and sour cherry trees in southern Pennsylvania. 

A decimation of the Yoshino trees would hamper the tourist industry, but birds, bees and butterflies would also lose out on a source of pollen and nectar early in the season. To protect against such threats, horticulturalists are creating new types of resistant cherry trees. 

The U.S. National Arboretum clones cherry trees from across the world but also develops their own varieties. One of their hybrids, called Prunus First Lady, stands tall, has stunning dark pink flowers, and is better adapted to colder temperatures.

“The goal is to develop hybrid cherries that we can introduce into the nursery trade,” says Piper Zettel, a horticulturalist at the U.S. National Arboretum in D.C. Some nurseries are already developing and distributing hybrids that are more resistant to cold and certain diseases too.

The Tidal Basin is the most iconic spot, but the pink flowers can be seen at East Potomac Park south of the basin, Stanton Park on Capitol Hill, Oxon Run Park in southeast D.C., and American University Park and Cleveland Park in northwest D.C. Visitors can also take a self-guided tour at the U.S. National Arboretum, which features 70 cherry tree varieties across 450 acres. Wherever you go, the flowers pop in unison.

This year, the National Park Service is adding more cherry trees than usual. In addition to the usual 90 trees annually, 300 more were replanted after being removed for a new seawall at the Tidal Basin years ago. Japan gifted another 250 trees in honor of America’s 250th anniversary.

(Best places to see cherry blossoms in the U.S.)

“We had a much wider mix of varieties that are going in than we took out,” Litterst says. “We want it all to be a little bit different mix genetically, so that the entire population is less susceptible to blight.”