Among the usual bevy of food crops grown in the Pacific Northwest exist a few unexpected delights from the Southern Hemisphere. Mashua, ulluco, oca and yacón are all edible native tubers from the Andean Mountains in South America. Spanish conquistadors first brought potatoes from the Andes to Europe in the 1530s, but ignored other root and tuber crops cultivated by the Incan people. These crops are now finally being recognized and made more widespread due to the importance of preserving genetic diversity of root and tuber crops as well as the importance of protecting those culturally significant plants that sustained indigenous people for thousands of years. Yacón (pronounced yah-CONE) in particular is making a larger splash in Seattle-area gardens and farms due to its potential health benefits as well as its value as a crop that is easy to grow and store.
Yacón (Polymnia sonchifolia) is kin to sunflowers, dahlias, sunchokes (a.k.a. Jerusalem artichokes) and other members of the daisy family (Asteraceae). It is a perennial plant that can grow four to five feet or taller and can produce small yellow flowers in late fall, though usually will not flower in our northern climate. Still, it will develop large edible tubers and rhizomes used to grow new plants. The sweet tubers contain few calories but hold a lot of water. The Spanish derived the word yacón from llaqon, the Quechuan word for “watery” or “water root.” It is believed that Incan travelers used the tubers as a water source while they were on the road.
Yacón is native to the region of the Andes from Colombia to northern Argentina. It is thought that early people living on the eastern humid slopes of the Andes (northern Bolivia to Central Peru) first discovered and later cultivated the wild plants. The tubers were likely used as a supplement to the diet rather than as a staple. After the Spanish conquest, it continued to remain an important food but cultivation declined and some species were likely lost. In the 1930s, Italian botanists grafted yacón to dahlias, sunflowers and sunchokes in order to breed new vegetables but World War II put an end to experimentation. Since then, yacón has been introduced to other parts of the world. It is now popular in Japan and is grown on a small scale in Europe and North America. Thanks to the efforts of people interested in keeping Andean crops from extinction, such as work done by the National Research Council (“Lost Crops of the Incas,” 1989), there is now a growing interest in studying and preserving these plants.
How Sweet It Is
Its high fiber, low calorie, water-filled nature — as well as its mild sweetness — make yacón a perfect diet food! Its flavor comes across as a cross between apple, pear and celery with a crunchy texture like jicama. Unlike apples, it does not turn brown when exposed to air. Freshly dug yacón contains fructooligosaccharidem (FOS), a type of sugar that humans cannot digest. After being stored for several weeks, it gets sweeter because the FOS converts to fructose. As such, they also get just a little bit more calorie dense but still only weigh in at 100 calories per pound. Exposure to sunlight also sweetens them up because the FOS turns into fructose, glucose and sometimes, sucrose.
Yacón is rich in fiber and potassium and low in vitamins and minerals. Research suggests that it contains prebiotics that promote colon health. One drawback is that the indigestible sugars can also cause gas. If you have trouble eating sunchokes, you may have the same experience with yacón but the experience will be less intense as the bacteria in our guts have an easier time breaking it down.
Yacón syrup has gained popularity as a sweetener. The sugars in syrup are concentrated so more of them are converted to fructose than unprocessed tubers contain. There have been a number of health claims made about the health benefits of yacón syrup including the ability to regulate blood sugar levels, lower “bad” cholesterol and blood pressure, help with weight loss, and improve liver and immune system functioning and digestive health. While some of these claims may prove to be true, diabetics and people with serious health concerns need to be careful because there are few studies on humans to date. In rare cases, people have experienced allergic reactions. Be cautious about using the leaves to make tea as some have suggested. The leaves may be toxic to the kidneys at high concentrations.
How To Grow It
Yacón is cloned from the crown of the plant that grows underground, similar to how dahlias are divided. The propagation rhizomes grow nodes or “eyes” whereas the storage tubers (the ones you eat) are often larger, can be shaped like a sphere or pear and are usually tan in color, but can also be white to purple depending on the variety. All of these descriptors, as well as the sweetness, may differ depending on the variety. If you purchase them from a grower, the rhizomes will usually be shipped bare and ready to prepare for planting, with directions on what to do. If you are already growing yacón, when you dig it up during dormancy cut off the crown, compost the foliage and store it for a few months. Give them a jump-start by cutting off chunks of the rhizome and planting them in pots in a warm and sunny place until the weather starts to warm up. Plants will get a better start if they already have a few leaves growing on them before they go into the ground.
This easy-to-grow plant doesn’t need a lot of nitrogen or phosphorus, but it does require some potassium. Finished compost is a good source of potassium. If more is needed per a soil test, use kelp, seaweed, greensand or a small amount of ashes from untreated wood. Yacón prefers soil that is slightly acidic (6.0 to 6.5 pH), but will grow in more neutral soil. It also likes it warm. Wait to plant until temperatures are consistently in the mid-60s. It prefers it to be just a little cooler than 80 degrees F, but will tolerate extreme heat (up to 104 degrees F) better than many other plants do, adapting well to a variety of conditions. It will tolerate a little drought, but will do better with regular watering. Give the plants room to grow and protection from high winds.
The largest tubers are produced during long, frost-free fall weather. Plants need a long time in the ground – up to 8 months - to produce mature tubers. Harvest anytime between mid-October and December depending on if there is an early frost. Take care not to damage the fragile tubers when digging them up. If the plants thrived, the harvest can be very productive and heavy! Remove the larger tubers and any damaged ones for eating but leave small ones attached to the rhizome. Wash off the crowns and let them dry completely before storing. Store the rhizomes in dry sand in a dry, cool (35-40 degrees F); if they get wet, they may rot.
How to Eat It
Storing the larger edible tubers you remove from the rhizomes is easy, just wash them off and put them in the fridge. They will last up to a year! The tubers may start to dry out and shrivel over time, but they are still perfectly fine to eat. Yacón can also be dried or made into syrup. If you freeze it, plan to eat it before it thaws as it will become mushy at room temperature.
Yacón is a versatile vegetable. Eat it raw or toss it in a stir fry or stew. Juice it or slice it up and bake a batch of yacón chips. Sauce it or turn it into chutney. As it grows in popularity, people will come up with creative new ways to prepare it. Yacón flour will probably start showing up on market shelves sometime soon!
Where To Find It
Locally, there are a few small farmers growing yacón and other Andean root crops. Cultivariable (www.cultivariable.com) is a small farm on the Washington State coast specializing in these crops. They may sell out of some items by spring, so get your order in soon! Peace Seedlings (http://peaceseedlingsseeds.blogspot.com) in Corvallis, Oregon, also sells tubers. In-state, Raintree Nursery www.raintreenursery.com in Morton will ship potted plants next spring.
If you don’t want to grow your own, you may still find fresh yacón tubers for eating but sometimes it is a matter of luck. If you have never tried it before, take a chance and try it if you spot it at a farmer’s market or holiday fair this December. It is easier to find yacón syrup, but that stuff is nothing like this sweet and crunchy root when eaten fresh!
For more information on uncommon edible plants from around the world visit the Garden Hotline online at www.gardenhotline.org or call us at 206-633-0224.