Gardening

How to propagate and grow Peruvian ground apple, aka yakon

How to propagate and grow Peruvian ground apple, aka yakon thumbnail
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Peruvian ground apple (also known as yacón) is a rare plant that produces sweet, delicious storage roots. It can be grown in much of the United States with relative ease and has traits that make it a far better crop than Jerusalem artichoke, its close relative.

In this article, you’ll find out how to grow and eat your own Peruvian ground apples!


About a decade ago, we decided to grow Jerusalem artichokes (Helianthus tuberosus). In case you’ve never heard of them, Jerusalem artichokes are members of the daisy family that produce edible tubers. Native to North America, they were a crop commonly grown by Native Americans. 

After harvest, I cooked and ate a few of the Jerusalem artichoke tubers. A short while later, I discovered firsthand one of the oft described problems with Jerusalem artichokes: the inulin in the tubers can not be broken down by the human digestive system, thus consumption causes gastric distress for many (not all) people who eat them. 

The 17th century English botanist John Goodyear may have described Jerusalem artichokes as accurately as anyone in history:  

“which way soever they be dressed and eaten, they stir and cause a filthy loathsome stinking wind within the body, thereby causing the belly to be pained and tormented, and are a meat more fit for swine than men.”  

Well, then.

Despite this unfortunate feature, we still see many people singing the praises of Jerusalem artichokes and have also seen them featured on menus at upscale restaurants. Caveat emptor.     

To make matters worse, despite not wanting to ever grow (or see) Jerusalem artichokes again, the plant continues to be an unwelcome guest in our garden a full decade later due to its numerous underground runners and tubers which produce new plants each spring. 

Peruvian ground apples: a much better alternative to Jerusalem artichokes     

Peruvian ground apple roots. These are relatively small. Under ideal conditions and a long growing season, a single Peruvian ground apple/yacon root can grow to up to 6 pounds.

Peruvian ground apple roots. These are relatively small. Under ideal conditions and a long growing season, a single Peruvian ground apple/yacon root can grow to up to 6 pounds.

A few years ago, we decided to try growing Peruvian ground apples (Smallanthus sonchifolius). Due to our negative experiences with Jerusalem artichokes, this decision was made only AFTER doing precautionary research on the plants, especially since the two species are relatively closely related. 

Peruvian ground apples are also commonly known as yacón. They’re often called “Peruvian ground apples” in English because they’re crispy and sweet, similar to an apple. In fact, they’re eaten and sold as a fruit, not a root/tuber, in their native region.

Western researchers studying the plant in Peru noted: 

“In the local markets of the Andes, yacon is classified as a fruit and sold together with chirimoyas, apples, avocados, pineapples, etc. and not with potatoes, oca, ulluco or mashua (Tropaeolum tuberosum), as a foreign observer would expect.”

Four reasons we much prefer Peruvian ground apples/yacón to Jerusalem artichokes:

  1. They don’t produce digestive distress; 
  2. They produce far greater yields than Jerusalem artichokes;
  3. They taste better;
  4. They’re easy to control (non-invasive) since they don’t spread via runners and tubers. 

Here’s a bit more detail pertaining to some of these aforementioned benefits: 

Digestive considerations

The reason Jerusalem artichokes cause gastric distress is because they contain high concentrations of inulin that the human digestive system can’t break down. Nevertheless, the inulin stimulates a feeding frenzy of inulin-eating bacteria in the human colon. Not to be too graphic, but that feeding frenzy results in several trillion bacterial emissions which then have to go somewhere. You can fill in the blanks from there.

As for yacón, researchers have found the following:

“Several carbohydrates are stored in the roots of yacon: fructose, glucose, sucrose, low polymerization degree (DP) oligosaccharides (DP 3 to 10 fructans), and traces of starch and inulin (Asami et al. 1989; Ohyama et al. 1990). Inulin, a high-DP oligofructan with DP of about 35, is a main storage compound in many plants of the Compositae family, such as Helianthus tuberosus and Dahlia sp. However, in yacon inulin appears to be only a minor component.” 

Yacon/Peruvian ground apple roots just out of the ground.

Yacon/Peruvian ground apple roots just out of the ground.

Thus the reason that Peruvian ground apples/yacón don’t cause gastric distress: they don’t contain very much inulin. 

One word of caution: yacón syrup is a highly concentrated product used as an alternative, lower-calorie sweetener by diabetics and health-conscious consumers. Due to how concentrated yacón syrup is, it does contain enough inulin to cause gastric distress if consumed in large quantities. 

Does yacón have medicinal benefits? 

Peruvian ground apples have long been considered a medicinal plant in their ancestral homeland. People eat them to control diabetes/blood sugar, treat digestive ailments, cure constipation, help with weight loss, and a wide range of other health benefits. 

Current research supports these traditional uses of yacón.

Yields: yacón versus Jerusalem artichoke

A key benefit of Peruvian ground apples vs Jerusalem artichokes is yield. Under ideal growing conditions:

  • a single Jerusalem artichoke plant can yield 3-6 pounds per plant
  • a single yacón plant can yield 20-30 pounds per plant

With all this information in mind, are you ready to grow Peruvian ground apples/yacón?  

How to grow Peruvian ground apples 

Peruvian ground apple/yacón is a fairly easy plant to grow. Ideal growing conditions include:

  • full sun (6-8+ hours of direct sunlight daily),
  • rich, biologically active soil amended with compost, 
  • 1″ water per week (maintain damp but not wet soil). 

Are yacóns drought-tolerant? 

This past summer, our yacón suffered through about 8 weeks of severe drought plus mid-90°F temps. We only irrigated them once during that time period, partly due to laziness and partly due to curiosity to see how they’d perform in drought conditions. 

The results? Smaller tubers and smaller per plant yield. The storage tubers likely helped the plant survive, but in so doing, not much energy storage took place. Now we know.  

Getting yacón plants or seeds

Yacón/Peruvian ground apples can NOT be grown from replanting the storage roots. This part of the plant (which is technically not a tuber) simply serves as energy storage for the plant.   

Instead, Yacón is typically grown via crown cuttings which produces clones of the original parent plant. This is the only method we’ve used to grow yacón thus far. However, yacón seeds are starting to become available for US growers through breeding organizations like Cultivariable.  

The crown of a small yacon plant post-harvest. The small rhizome buds (see pointing finger) are the parts used to grow new plants the following year. Don't remove the soil or small roots from the root crown prior to storage. You do want to allow the root crown to completely dry out so that it doesn't rot or mold.

The crown of a small yacon plant post-harvest. The small rhizome buds (see pointing finger) are the parts used to grow new plants the following year. Don’t remove the soil or small roots from the root crown prior to storage. You do want to allow the root crown to completely dry out so that it doesn’t rot or mold. We’ll discuss yacon propagation in detail below.

A number of online retailers provide Peruvian ground apple starts grown via crown cuttings. (Do a Google search to find the most current sellers and varieties.) Sellers will ship young plants from spring – early summer after any chance of the plants being killed by cold weather during transit has passed.  

Simply plant these young plants in a full sun, fertile spot amended with compost in your garden. 

Provide support via large tomato cages

An additional recommendation when growing yacón: place a large, sturdy tomato cage over each plant.

The crown will send up multiple stalks throughout the growing season.

As these stalks mature, the weight of the 6′ tall stalks will cause them to flop to the ground. Without support/caging, you’ll end up with sprawled plants – or snapped stalks if you get heavy winds. 

Me standing behind a sprawling, uncaged yacon/Peruvian ground apple plant that was grown without a cage supporting it. For size, reference I'm a little over 6'1

Me standing behind a sprawling, uncaged yacon/Peruvian ground apple plant that was grown without a cage supporting it. For size, reference I’m a little over 6’1″.

(Read our article about how to make your own heavy duty, long-lasting plant cages.)  

Harvesting Peruvian ground apples/yacón

For ideal root production/yield, yacón needs 7+ months of frost-free weather.

If you live in a cooler climate region, don’t be discouraged! You can still grow yacón. Just plan on having a smaller harvest.  

We harvest our Peruvian ground apples in the fall after our first frost burns back the leaves.

Yacon leaves and flower buds burned back by the first frost of fall. At this point, it's time to harvest the roots.

Yacon leaves and flower buds burned back by the first frost of fall. At this point, it’s time to harvest the roots.

Here’s how:

1. Remove stalks

Use loppers to cut the stalks back about 1-2″ above ground level. 

2. Dig roots

Removing the storage roots from the ground can be a little tricky, especially if you have large, deep roots. Ideally, you can dig down on one side of the plant by hand to locate the beginning of the storage roots, then plunge a shovel in and pop the entire root system out of the ground. That way, you don’t cut any of the roots in half. 

Or if you’re in a rush and you don’t mind chopping a few of your storage roots, you can just plunge your shovel in the ground to one side of the plant then pull out the root ball. Be sure to feel around the hole with your hands before moving on to make sure you’ve harvested all the storage roots!  

3. Cut & rinse storage roots, save rhizome

You’ll want to cut the large storage roots off of the plant using pruners.

Remove the large yacon roots with pruners, but leave all the other smaller ones attached to the plant's crown. These smaller roots will help keep the crown/rhizomes alive for planting the following year.

Remove the large yacon roots with pruners, but leave all the other smaller ones attached to the plant’s crown. These smaller roots will help keep the crown/rhizomes alive for planting the following year.

Rinse the storage roots to remove dirt. 

Involving your ducks in the rinsing of your yacon roots isn't required, but it is recommended.

Involving your ducks in the rinsing of your yacon roots isn’t required, but it is recommended. Also note that any roots that have been cut in half during digging should be eaten first.

What’s left on the plant is the rhizome plus smaller feeder roots. We store the whole thing (roots, dirt and all) in open cardboard boxes in our garage to allow them to dry without rotting. The rhizome will be used to propagate more Peruvian ground apple plants the following year. (More on that below.)  

4. Sun cure/rest before eating

Yacón roots eaten immediately after harvest are ok, but not great. They’re sweet and juicy, but also have a sligthly bitter flavor that some people might find off putting. They’re also relatively bland at this point. 

Traditionally, yacón roots are left to cure in the sun for several days after harvest, which significantly improves/sweetens the flavor and removes any bitter notes. Once the skin starts to wrinkle, they’re eaten or brought to market.  

Here’s the curing regimen we’ve found works for our relatively small yacón roots (1 pound and under):

  • leave in sun for up to 1 day;
  • bring into indoor storage for 1 week or until skin wrinkles;
  • eat.

We leave our yacon roots on the counter for up to 2-3 weeks and eat them like apples. For longer term storage (2+ months), put your roots into a produce or ziploc bag and put them in the veggie drawer in your fridge.    

Saving and propagating your yacón rhizome

Remember: after harvest you’ll need to store your DRY yacón crown in a cold/dry environment. A cool shed or garage is ideal, but temps should NOT drop below freezing or this can damage or kill the plant.   

The dried over-wintered crown of a yacon/Peruvian ground apple plant, smaller roots left attached for energy. The rhizome is about to be cut into chunks and used to propagate new plants.

The dried over-wintered crown of a yacon/Peruvian ground apple plant, smaller roots left attached for energy. The rhizome is about to be cut into chunks and used to propagate new plants.

In mid-late January, we cut off ~7 ounce pieces of the crown, each containing separate rhizome buds/growth tips.

Propagating yacon/Peruvian ground apple via crown cuttings from the rhizome. Here's a closer look at a piece that's ideal for planting. Bury each piece so that the top is 1/2-1

Propagating yacon/Peruvian ground apple via crown cuttings from the rhizome. Here’s a closer look at a piece that’s ideal for planting. Bury each piece so that the top is just at or slightly below the soil surface.

Another look at a piece of yacon crown with the stem from the previous year's plant still attached. In the next image you can see where the old stem was cut back to the base and the rhizome was buried in a small pot.

Another look at a piece of yacon crown with the stem from the previous year’s plant still attached. In the next image you can see where the old stem was cut back to the base and the rhizome was buried in a small pot.

Each piece is then placed into a small plastic pot with damp potting soil.

Within ~2 weeks, new growth emerges, at which point each pot is placed under our DIY indoor grow light system.

Welcome back! Yacon rhizomes sprouting to life in late winter.

Welcome back! Yacon rhizomes sprouting to life in late winter.

If you don’t have grow lights, a sunny south-facing window will do. Any time outdoor temperatures are over 50°F, you can start putting your young Peruvian ground apple plants outdoors in direct sunlight.   

Depending on the size of container you start them in, you may need to pot them up 1-2 times along the way. As soon as your last frost date has passed and there are no frosts or freezes in your weather forecast, transplant them into their summer destination. Repeat this process year after year! 

Getting bigger! About a month after this photo was taken, we transplanted our Peruvian ground apple plants into the garden.

Getting bigger! About a month after this photo was taken, we transplanted our young Peruvian ground apple plants into the garden.

A fully mature yacón crown that’s had 7+ months to grow can propagate a dozen or more new plants the following year. 

How to eat yacón/Peruvian ground apple 

We’ve saved the best for last! How do you eat yacón? Lots of ways…

The simplest way to eat yacón is just like you’d eat a piece of fruit: chomp away on the whole raw root. (This is the way they’re often eaten in Peru.)  

Our favorite way to eat Peruvian ground apples take about 5 minutes of prep: slice them thin then top with fresh citrus from our potted citrus trees (either Meyer lemon juice or finger lime pearls). The sweet + sour combination perfectly balance each other out. 

Garden-to-table perfection! Thin-sliced yacon/Peruvian ground apples with finger lime pearls (aka citrus caviar) and garnished with fresh baby chocolate mint leaves. Before plating, we gave the sliced yacon a quick bath in Meyer lemon juice to prevent browning/oxidation.

Garden-to-table perfection! Thin-sliced yacon/Peruvian ground apples with finger lime pearls (aka citrus caviar) and garnished with fresh baby chocolate mint leaves. Before plating, we gave the sliced yacon a quick bath in Meyer lemon juice to prevent browning/oxidation.

Most people use a carrot peeler to remove the skin before eating yacón since it does impart a slight bitter flavor. We prefer to eat the whole root, skin and all, since it provides extra fiber and nutrients.  

You can also eat yacón in countless other recipes where a sweet, crispy ingredient is desired:

  • diced into salad,
  • grated and added to slaw,
  • diced and pickled/fermented, 
  • added to stews or soups (it stays sweet and crispy when cooked, similar to parsnips), 
  • grated and added to pies and other sweet baked goods as a substitute for processed sugar. 

Do keep in mind that yacón flesh will oxidize and turn brown soon after you cut them and expose them to air, similar to a sliced apple. This does not impact flavor, but can make it less attractive. To prevent oxidation, simply coat your sliced yacóns with lemon juice. 


We hope you enjoy growing and using Peruvian ground apples/yacón! We think this South American root crop should be a staple in gardens, farms, and kitchens in North America as well.  

KIGI,

Other interesting gardening articles you might enjoy: 

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