Yacon is a large tuber, harvested in late Autumn when the foliage has been killed by the first light frosts. It’s extremely prolific, but needs to be harvested and kept frost free, then replanted in spring.
Defra are currently cautioning against growing yacon because of the risk that it might harbour or spread potato yellowing virus. You are not allowed to import new yacon tubers and advised not to buy and sell it in the UK. You are allowed to grow it for personal consumption, although saving of tubers from year to year is not recommended (if you decide to follow this advise then you effectively won’t be able to grow it next year). For more see the PDF below:
planthealthportal.defra.gov.uk
I use a rating system to help me decide what to grow and it considers lots of factors, but the main ones are how tasty it is, healthy it is to eat, how expensive it is to buy, how big it's harvest is, when it's harvest period is and whether I can buy it organically and if not how much it's sprayed.
Yacon scores moderately well in this rating system. It’s very prolific, we harvested 25lb of tubers (plus 6 new plants) from 1 original tuber grown in 1m2. That’s not as big as a good harvest of potatoes, but Yacon is very different and maybe healthier, containing no human digestible carbohydrates (they are digested by the gut bacteria) it’s renowned as a great food for people with diabetes.
It has a lovely texture and can be eaten fresh and cooked, my family likened it to an crispy apple/pear fresh or water chestnut cooked, but superior.
It also looks amazing in the garden, huge lush growth and no pests.
<aside> 💡
Yacon is mainly water, after curing it has about 20 calories per 100g which is so low as to be almost calorie free
</aside>
I found it hard to believe too, but yacon is considered a healthy food primarily because of its unique carbohydrate content. Unlike most tubers, yacon contains very low levels of human-digestible carbohydrates when first harvested. Instead, it is rich in fructooligosaccharides (FOS), a type of prebiotic that is not digested by human enzymes. These prebiotics pass through the digestive tract and are fermented by beneficial bacteria in the colon, promoting gut health.
About 2/3 of my crop from 3m2 of shady growing area
The low glycaemic index of yacon makes it an excellent food choice for individuals with diabetes or those looking to manage blood sugar levels, as it does not cause spikes in blood glucose. Additionally, the fermentation process in the gut can lead to the production of short-chain fatty acids, which have been associated with various health benefits, including improved gut health and a reduced risk of certain diseases.
Overall, yacon's unique carbohydrate profile not only supports digestive health but also contributes to its reputation as a healthful food alternative to more carbohydrate-dense tubers like potatoes.
However, when you cure it, the fructooligosaccharides will start to convert slowly to human digestible sugars and the longer you cure it, especially if exposed to sunlight, the more sugar/fructose it will contain, but also the sweeter it will be so beware!
Just about to Harvest my bed in November
Given enough space and a good year yacon is extremely prolific and unless you really love them one plant might be enough per person, I’d certainly not grow more than two in your first year. Increase from there if you really like it, the plants can be separated - at harvest time - to expand the number that you grow.
Yacon does grow acceptably in large containers, but it’s a deep rooted plant, so for maximum yield it benefits from being planted in the ground. My experience in containers though is very positive because I often find that plants grown in the ground produce huge tubers which are difficult to eat in a single sitting and even more difficult to dig up without damage!