An Introduction to Sweet, Crunchy Yacon

Yacon's underground yield

Yacon (Smallanthus sonchifolius) produces two types of underground yield. In the picture at the top of this post the planting rhizomes (see below) have been twisted off and we see just the large, edible tubers that look a bit like sweet potatoes. 

In the picture below, I've twisted off the edible tubers to show just the second type of yield — the purple-ish/reddish rhizomes waiting to be divided for planting. The rhizomes sit above the tubers, directly at the base of the stem. They can be eaten when young but if you did that you'd be eating your propagation material — this is what the new yacon plants are going to grow from. 

Foliage and flowers

Yacon is not the tidiest plant. As you can see in the pictures below, it can get leggy and sprawling, its flowers are small and not noticeable, and its foliage can be messy.  

Here's a closer pic of the foliage...

Yacon uses

When I was first learning about yacon, some writers said its foliage was an appealing fodder for goats and pigs, but this has not been my experience (I am sure goats and pigs would love the tubers, but I've never had any spare).

I believe you can make a medicinal tea with the leaves, but I haven't tried this. 

I also haven't found yacon foliage to be very useful mulch provider, as its foliage loses its bulk very quickly and just sort of dissolves after a short time on the ground.

But, yacon is very good to eat.

To harvest all of it at once for eating, dig carefully around and under and lift the whole plant to find the large, smooth brown tubers, after the plant has flowered and then died back at the end of summer. 

One way to know there are tubers under there is if you can see the soil mounding up around the base of the plant. Sometimes you can see them protruding a bit, but that probably means your mulch layer isn't thick enough.

Or you can do what I tend to do, which is to dig carefully under one side of the plant till you find a tuber, clear around it and twist it off, then refill the hole you've made with soil/compost, replace the mulch, and go have dinner. 

To prepare it for eating, peel the tuber thickly to remove the smooth outer brown skin and the inner white skin and reveal the pale, translucent, sweet, crunchy flesh. Put it in water as you peel it, to stop it going brown.

Eat it immediately, in large quantities, like my son does, or chop it into salads or put it in stir fries or stews. No matter what you do to it or how long you cook it (within reason), it doesn't lose its crunch and its sweetness.

My kids prefer it raw; I like it cooked. To me, raw it can taste a bit flat and watery (it's definitely a thirst quencher when eaten raw) and cooking it intensifies the flavor a bit so it has more body to it. 

Eating large quantities of raw yakon may lead to some harmless but entertaining flatulence (which is part of its appeal for my son); this is no longer a problem after its cooked.

Planting yacon

You saw the clump of rhizomes in the picture above; below, that clump has been divided ready for planting.

Those little bits of rhizome will all sprout leaves from their little knobs, which will look like this...

More information about yacon

GreenHarvest.com.au has a useful profile with lots more details and better pictures of yacon, as well as more growing information. 

And here at RainTree.com is a comprehensive article about yacon's origins and its herbal properties and actions, and other uses for it besides just eating the tubers. 

Some other bits and pieces I've learned about yacon: 

• It evolved as an under-story plant, so it doesn't mind a bit of shade, but it seems equally happy in full sun.
  
• It needs a long, warm growing season. Plant it in September or October (Southern Hemisphere) and it will be flowering and then dying back ready for you to harvest the tubers as the cooler weather approaches the following year.  
  
• The tubers do keep, but the sugars in them begin to change within a few days of storage from a kind we can't digest (so good for diabetics and people who need to be careful with blood sugar levels, and this is the reason for the flatulence when you eat it raw) to a kind we can digest. Since more sugar isn't something we need, once I've harvested it I like to make sure it gets eaten quickly, or I cook and freeze it in chunks ready to add to meals as needed.
  
• Some writers describe yacon as drought tolerant, which it probably is if you're wanting it to just survive, but for a good yield, yacon needs deep, cared-for soil and consistent moisture. My previous yacon plantings have been neglected due to being in the wrong places, where I don't see them often enough to remember to water them when its dry and to keep their mulch topped up. Now I keep it where I'll see it every day and be reminded to care for it. 
• The kids love yacon and they can harvest and eat it without help, so that's another reason to place it close by.
• We get visits from tuber-chewing rodents. They're not interested in yacon until its tubers are starting to be sweet and edible, and by then the yacon is established and can withstand a visit from bandicoots or rats. When that happens I try to harvest the chewed tubers right away, before they start rotting, cut away the chewed bits, and use the rest. If the chomping gets too much, it's time to lift the whole plant up and bring the harvest inside.