Beware the Dahlia

The dahlia has captured the eye of many a gardener throughout the ages, but these edible flowers have an appeal that's more than just skin deep.

Purple Dahlia

Dahlias have an uncanny ability to ensnare even the most diverse gardener.

Photo courtesy www.RareSeeds.com

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Beware the dahlia; this flower possesses a bewitching beauty with a penchant for stealing the hearts of gardeners. Opening your garden gates to this indomitable muse will no doubt wreak havoc on the herbaceous hierarchy. Dahlias have an uncanny ability to ensnare even the most diverse gardener. Once under the dahlias spell, gardeners will find themselves feverishly turning over extra space to accommodate multiple varieties. With so many colors, sizes and forms, who can plant just one?

The dahlia has come a long way to reign supreme in gardens across the globe. Wild ancestors grew in the highlands of Mexico and Guatemala, where it was considered a food and water source (the stems are quite watery). A popular myth says the dahlia was Montezuma’s favorite flower and could be found growing in his stunning gardens. In actuality, the wild dahlia did not enrapture the Aztecs. Perhaps because they grew so prolifically, they were considered a useful weed rather than a stunning ornamental.

Francisco Hernandez was the physician to Phillip II of Spain. He was sent to Mexico in 1570 to study the natural resources of the area. There he observed a useful flowering plant that the indigenous peoples both foraged and cultivated for a food crop, as well as a water source. This is considered the first written description of the flower called “Acocotli” (meaning water pipe flower) by the Aztecs. The name dahlia would not come about for another 200 years.

Although Francisco Hernandez is credited with the first description and illustration of the dahlia, there is an earlier illustration that some believe to be a description of the dahlia. As a result of the Spanish conquest of Mexico in the mid-1500s, the college of Santa Cruz was established and dedicated to the education of Aztec boys. Likely, the first book on the medicinal plants of the new world was written here by two Aztec students. The Badianus Manuscript contained several colored illustrations of New World medicinal plants, including what some believe to be the wild dahlia. However, the illustration and description are not considered accurate enough to confirm that the authors were referring to the dahlia. Unbelievably, the Badianus Manuscript was lost for 400 years until it was rediscovered in 1931 at the Vatican Library.

In the 200 years since the beginning of Spanish occupation, the dahlia is believed to have been cultivated in the botanical gardens of Mexico City. It was not until the late 1700s that the director of the Mexico City Botanical Garden sent dahlia seeds to the Royal Botanical Garden of Madrid. Just three varieties of dahlias were sent to Madrid (there are over 42 species). Each was planted and named within the genus Dahlia, which was named for the Swedish botanist Anders Dahl.

The dahlia craze got off to a slow start in Europe, possibly because the initial intention of many breeders was to develop dahlias as a food crop. The first dahlias sent to Europe did not catch the eye of plant breeders; the flowers were not considered particularly striking. However, by the early 18th century the first double forms were introduced. Once breeders discovered the astounding range of genetic diversity the dahlia became very popular, with only a brief lull in popularity in the mid-1800s. Since then, breeders have created a boundless spectrum of forms and colors; we now enjoy over 20,000 named dahlia breeds. Dahlias owe this extraordinary genetic diversity to what is called polyploidy. Dahlias are octoploids, which means they have eight sets of homologous chromosomes; this is four times the number of chromosome pairs that most plants have. This results in a wide range of genetic expression that includes many colors and forms.

‘Haley Jane’ is a semi-cactus dahlia introduced in 1978.

In 1872 a shipment of dahlias from Mexico to the Netherlands was almost completely destroyed. J.T. Vanderburg was only able to salvage one tuber from an entire box of rotten plant material. This lone survivor would take the dahlia world by storm; the double petals were curved backward, unlike any other dahlia in Europe at the time. This entirely new dahlia form was called “stars of the devil” in France; to the rest of the world they are known as the cactus dahlias.

‘Mom’s Special Dahlia,’ a decorative “dinner plate” dahlia

Often referred to as dinner plate dahlias, the official name for this class of giant dahlias is actually decorative. The behemoth flower heads can reach 12 inches across on 5-foot tall plants.

Dahlias have been bred into an enormous palette of colors; blue, however, remains elusive. In 1846 the Caledonia Horticultural Society of Edinburgh posed a challenge: 2,000 pounds to the first person to create a blue dahlia. Sadly, no one has ever successfully produced a true blue dahlia.

‘Bishop of Llandaff,’ an old double peony type

This is an award winning dahlia, admired for the juxtaposition of its striking black foliage against velvety red flowers. ‘Bishop of Llandaff’ was introduced in the early 1920s and originally named ‘Bishop Hughes.’ The bishop did not wish to have a flower named in his honor, and the name was changed to ‘Bishop of Llandaff.’ In 1928 it was given an award of merit by the Royal Horticultural Society, and in 2004 it was named one of the best plants of the past 200 years by the same society.

Baker Creek: under the dahlias spell

Last growing season, Baker Creek was transformed into a lush dahlia gallery. The entire farm, top to bottom, became consumed with dahlia fever. Over 150 different dahlia cultivars were planted in any space that could accommodate them. Mass plantings of dahlias will take your breath away; the intense colors and textures create a garden landscape fit for Alice’s Wonderland.

These stunning dahlias look good enough to eat; why not? The petals and tubers are edible! Dahlias have been considered a viable food crop throughout history, but for some reason, eating dahlias hasn’t quite taken off in popularity. To most, the idea of digging up these beautiful flowers to eat feels like heresy.

The tubers are the most nutritious and substantial part of the plant; they are safe to eat raw or cooked. Over the years, dahlia breeders have focused their efforts on creating cultivars with brilliant colors and forms, often disregarding tuber quality. This breeding has effectively created some of the most incredible, flamboyant flowers, often with small or bland, bitter-tasting tubers. So when Jere Gettle asked me to conduct a taste test of some of the 150 cultivars of dahlias grown at Baker Creek this season, I reluctantly agreed. My goal was to find some of the tastiest tuber-producing cultivars. If beauty and bad taste were analogous in dahlias, I was in dire straits; our dahlia collection this season was stunning!

Fortunately, the correlation between beauty and off-putting taste does not always hold true. Through a combination of trial and error, as well as a bit of research and expert advice, I was able to unearth a few dahlia cultivars worthy of a spot in the root cellar and on the plate.

My hunt began in the massive pile of dahlia tubers stored for the winter at the Baker Creek. We have amassed a collection of 150 spectacular cultivars; each had to be lovingly dug up and bagged according to type. My first goal was to separate the tubers by size; the smaller, stringy tubers would not be considered good for eating. From there I selected a handful of large tubers to taste, hoping to discover the next “it girl” in the edible tuber craze (jicama would be so yesterday’s news!). I was imagining something akin to a sweet potato in flavor with a firmer texture.

Then the taste tests began; the guidelines were simple enough: Tubers were noted for flavor and texture. The range was striking; some tubers like ‘Jitterbugand ‘Soulman Anemone’ had a celery-carrot-top flavor that was pleasant and that I will plant next season for eating. Others, like ‘Crazy Loveand ‘Ali Oop,’ garnered tasting notes like “astringent,” “bitter,” “stringy texture,” and “nothing to write home about.” The top pick was a cultivar called ‘Crazy Legs,’ which I noted had a delicious carrot flavor with a crisp, almost-water-chestnut texture. However, I just couldn’t find my “it girl;” I was looking for the tuber to end all tubers. So I consulted an expert, a grower who considers dahlias more than just a pretty face.

William Woys Weaver has written roughly 15 books and hundreds of articles on food and gardening. He maintains a farm in his native Pennsylvania, where he grows heirlooms and rare varieties. There he has been working on selectively breeding dahlias, not primarily for zany colored flowers or disease resistance like most breeders, but for dahlias with superb eating quality. He was happy to share with me some of his dahlia wisdom. He has been focusing on bigger tubers; they are more practical for cooking and have a much better storage quality. Dr. Weaver stresses the importance of growing organically. Dahlias are heavy feeders that take up the nutrients in the soil aggressively; if there are toxic chemicals, dahlias will take them up and become unsafe for people to eat. He recommends growing dahlia tubers organically for a season (well composted horse manure is a great fertilizer) to rid the plants of any toxins they may have been exposed to before you purchased them. Since dahlias are not usually considered an edible, the tubers can be treated with harsh chemicals not considered safe for humans to eat. Never eat the tubers right from the store or nursery. I could feel the perfect tuber within reach; Dr. Weaver had the guidelines for growing a winning culinary dahlia, but has he found “the one?"

Perhaps in my quest for the perfect dahlia I had forgotten the reason why I love working in the garden: the pace. Time seems to stop in the garden. You cannot really rush plants, and the fast paced rat race whirls outside while you carefully tend your plants. Even when you are working at a fast pace in the garden, the flora and fauna continue on their relaxed pace. Plants are everything that’s right in the world; they don’t move at the speed of light. They aren’t cheap and fast; they’re slow and dependable. In this time of instant gratification it can be hard to keep in mind that selective breeding is not an overnight process. It has taken years for dahlias to reach the zenith of diversity that we enjoy today — the hundreds of cultivars we have at our disposal speak for years of hard work by diligent breeders, selecting and breeding for unique colors and forms. With so many years of dahlia breeding in the opposite direction, Dr. Weaver and his assistant, Owen Taylor, have been methodically selecting for the tastiest tubers from good heirloom cultivars. Like life in the garden, it isn’t a lightning fast process.

Dr. Weaver was able to let me in on the progress of his work to whet my appetite for tuber cultivars to come. When these dahlia cultivars are perfected, Baker Creek will offer the tubers for sale, and the edible dahlia will finally have its day. He informed me that he is working on delicious pink and purple colored tubers, an incredible feat considering most dahlia tubers have a dull brown color far less dazzling than a russet potato. For those who just can’t wait another season, Dr. Weaver also informed me of an old heirloom dahlia worth eating. ‘Yellow Gem’ dahlia boasts big, round, yellow tubers. They have a sweet flavor and a crisp texture that doesn’t become mushy when cooked. They lend a sweet flavor and crunchy texture to soups and stir-fries. The flowers aren’t bad to look at either; they are a lovely yellow pompon type.


Shannon McCabe is a gardener and writer for Baker Creek Heirloom Seeds. She is a graduate of the University of Rhode Island with a bachelor's in horticulture and sustainable agriculture. She has been a market farmer on Block Island, a small island off the coast of Rhode Island, where she grew up, as well as an orchard keeper for the University of Rhode Island. In her spare time she likes to make cheese, ride horses, and listen to psychedelic rock music.