When Dan Pearson was eight years old, his father brought a batch of brown tubers home and planted them in the yard. Intrigued, Dan helped tend the vigorous plants that sprang from them and watched them bloom into flashy, brightly hued flowers, some as big as a dinner plate. He memorized the names of all 30 varieties.

The next spring, tickled by his son’s interest, Chester Pearson ’59 planted even more. Their yard was so full of color that cars would slow as they drove by. One day when a car stopped, Dan offered to sell some blooms for a dollar. Pretty soon it was a regular event. “I’d run in the house and get a steak knife out of the drawer and cut them a bouquet,” he says. The next year the Pearsons hung a “Dan’s Dahlias” sign, and the kid was in business.

Dan Pearson and his daughter Alyssa pick flowers for the farmer's marke
Dan Pearson and his daughter Alyssa pick flowers for the farmer’s market. (Courtesy Mieke Pearson)

Dan ’95 tells this story while tending his busy booth at the Northwest Flower & Garden Show this February. What seemed to be a summer hobby for an eight-year-old has become a vocation for Pearson, who now has three acres and 300 varieties of dahlias, a winter business selling tubers, and a summer business selling blooms.

By the time he was 11, Dan was selling his flowers at the Olympia Farmers Market. Since the Pearsons lived a ways out in the country, Dan would ride with his mother into town and unload his jars and boxes before she headed off to get groceries. When she was done, she’d pick him up and head home.

“He was a really small boy,” says Chester Pearson. “A lot of little old ladies wanted to give this kid their money.” There were some, though, who didn’t realize he was the vendor, says Dan. “They’d see this child arranging the jars and would come up to me and say, ‘Now, honey, don’t touch the flowers.'”

All his earnings went into savings for college. Dan put himself through Washington State University with his dahlia dollars, studying for a landscape architecture degree and going home each summer to continue his flower farm. Though he worked for a landscaping firm for several years after college, the flower business grew so big he had to focus on it full time.

In dahlias, Dan found a business particularly well-suited to the climate and people of western Washington. A native of the Mexican highlands, the dahlia loves the mild weather and cool summers of the Northwest—and the Northwest loves it back. Many states have a dahlia society, and some, like California, have several. But Washington tops out at 13.

While many people simply prize dahlias for their vigor and color and the fact that they bloom in late summer, when most flowers go dormant, there is a subculture of hard-core dahlia aficionados, especially here in Washington. These are the competitive dahlia growers, the dahlia-obsessed who tend their plants daily, who set up parasols around them to protect them from too much sun, who shell out big money for the newest varieties, and who study the art of arranging them so they can win prizes at flower shows. “There is a way to groom them, and pluck off the unsightly petals and leaves, but you’re not supposed to do that,” says Chester Pearson, who has become—you guessed it—one of those dahlia fanatics. During the blooming season he’s constantly watching his plants to decide what his entry might be. And every weekend it’s a new show and a new competition, he says.

With nine sizes, 18 classifications of form—including pompon, peony, and water lily—and 15 colors or color combinations, the dahlia has a lot going on. “Some people say a dahlia is a man’s flower,” says Dan, pointing to his father and family friend Dick Porter, who love the bloom because it’s so showy. But as an American Dahlia Society accredited judge, Dan’s seen serious cultivators of both genders.

“It’s the competitive spirit,” says Porter, a retiree who has a few hundred dahlia plants in his yard near Bellingham. “We’re always looking for the greatest new one.” Pearson the elder grins and nods, admitting that it doesn’t hurt that when it comes to spring planting time, he gets the pick of his son’s supply.

In spite of the flower’s popularity, only a few scientists in the country work specifically with ornamental dahlias. Narrow that down to the pathogens that affect the plant, and the list of experts gets even smaller. One of those rare plant pathologists who worked with dahlias was Sam Smith, who studied the subject at Penn State years before coming to WSU to be president. In his honor, the American Dahlia Society established a dahlia research endowment at WSU in his name.

Hannu Pappu
Hannu Pappu (Courtesy Deborah Dietz)

Hanu Pappu is the second plant virologist at WSU to hold the Smith endowment, and as such is charged with studying diseases that affect dahlias. His work is leading to new disease identification aids, including the development of field tests so that growers can perform their own diagnoses.

When asked if he grows dahlias at home, Pappu says he’s not into healthy plants. “It’s the sick ones that fascinate me,” he says. A virus like the dahlia mosaic virus (DMV) can impair the quality of the flowers and affect the vigor of the plant. “But isn’t that beautiful,” says Pappu as he shows a picture of an infected leaf with a patchwork of dark and light greens.

Pappu has had an exciting few years since coming to WSU in 2002, discovering, first, that diseased plants have not one, but three separate viruses, and second, that one of the three DMV viruses is actually inserting itself into the DNA of the plant and reproducing itself as the plant reproduces.

Viruses won’t often kill the plant, but they will weaken and discolor it. Because they can be transmitted through aphids, they can easily spread to other dahlias nearby. Growers and hobbyists who find virus in their dahlias tend to hang on to the plants because of sentimental attachment, says Pappu. But professional growers and garden centers are serious about detecting disease and must act quickly to eliminate the infected dahlias, or lose business and credibility.

Dahlias are only part of Pappu’s research. He also works with vegetable crops like potatoes and onions. His is a tale of two tubers, he says. On one end you have the affordable potato. On the other, a desirable new dahlia can sell for hundreds of dollars.

Though the dahlias we grow now are from varieties imported from Europe, the plant’s origin, like that of the potato, is in the Americas. The Aztecs used dahlias as both medicine and garden decoration. According to plant scientist Paul Sorensen’s “The Dahlia: An Early History,” the first mention of the dahlia appears in The Badianus Manuscript, a book on Indian medicinal herbs written in 1552 by two Aztec Indians attending the college of Santa Cruz in Mexico. The rare illustrated manuscript was brought to Spain and then disappeared into the Vatican library for several hundred years until it was rediscovered in 1929.

Like that manuscript, the dahlia was brought into Europe through Spain by early explorers. It was a lively time for horticulture. Many illustrious gardens were seeking to incorporate exotic plants from around the world. The Royal Botanical Garden in Madrid sent specimens of the plant to Germany, England, Italy, France, and the Netherlands.

Because of its rarity and showy nature, the dahlia was a treasured bloom. In 1828 England, a new dahlia could fetch a very high price, more than several weeks’ wages for a laborer. Gardeners all over Europe were intensely breeding and hybridizing the plant to achieve new colors, fuller and showier blooms, prettier foliage, and stronger stems. Their efforts became a foundation for the thousands of varieties that exist today.

The plant has retained its value as a bloom. For a commercial grower, an acre of dahlias could be worth as much as $200,000. With that much at stake, it’s no wonder they’re concerned about viruses.

To get a better understanding of dahlia mosaic virus, Pappu and his students are turning back to the wild species in Mexico. With the help of geneticist Dayle Saar, a colleague at Murray State University who searches for wild dahlias, Pappu has been able to discover that some of the viruses that affect dahlias were present in the plant’s ancestors.

To date, scientists have identified 36 different species of dahlia in Mexico. By studying them and their infection and interaction with viruses, Pappu hopes to find a way to address the virus in the garden-variety plant.

Until more is known about the viruses, commercial growers like Dan Pearson use quarantine sites to grow out new varieties before introducing them to their farms. But Dan’s biggest challenge so far hasn’t been disease. It was a much larger culprit.

In the summer of 1994 a major, even earth-shaking, event wiped out Dan’s crop. While he was away at a family wedding in California, the neighbor’s Holsteins broke loose and “ate a whole three acres of dahlias to the ground, broke the wooden stakes, and destroyed all the plastic identification ribbons,” says Dan. “They wiped me out that year.”

But he maintains a sense of humor about it, which is why his logo is a cow munching a dahlia. “It keeps me humble, reminds me of my roots,” he says.


Think your dahlia has a disease? Want to know more about the plant? Check out the dahlia virus website of Hanu R. Pappu, Associate Professor and President Samuel H. Smith Endowed Chair in Plant Virology.