Many people contact us asking for help with choosing a yacon variety. Yacon is not always an easy plant to characterize. Many traits vary quite a bit from one year to the next. For example, we used to list New Zealand and Cajamarca as short varieties, but we have since discovered that in some years they can actually be the tallest. We will probably continue to refine these comparisons, but I think they are generally pretty reliable.
Tuber Formation ranges from early to late. Early varieties yield well at about 5 months, while late varieties need 7 or 8 months depending on climate.
Plant Height ranges from short to tall, as measured in our climate. Many varieties grow taller in warmer climates, so your results might not match ours exactly. If you are in a tropical climate or a latitude with extra long days, like Alaska, your results might be totally different. Short varieties reach about 5 feet tall in 8 months and tall varieties may reach 7 feet or more.
Yield ranges from low to high, again measured in our climate. Your yields will likely be lower than ours, although they will probably be proportional. We define a high yield as a full root ball (tubers and crown) that weighs 25 pounds or more and low as 15 pounds or less. Unless you are growing for market, you probably won’t find this particularly significant. Even low yielding varieties produce a lot of tubers.
Flowering ranges from early to late. Early flowering begins at about 6 months and late flower at about 8 months or later. Flowering only matters if you want to try yacon breeding or you just like the flowers.
Sweetness is an absolute scale for both the level of sweetness at harvest and after at least three weeks of exposure to sunlight. Some varieties are already fairly sweet at harvest, but most get sweeter with exposure to sunlight. Some change more than others. Flavor is subjective, but I think of yacon as a combination of flavors of pear and celery. Most sweet varieties are more pear than celery, intermediate are about an even balance, and least sweet varieties are more celery than pear.
Tuber color is quite variable and depends on climate and maturity of the plant. Some varieties are different here every year, while others are more consistent. I’m reporting what we expect to see here, but what you see may be quite a bit different, particularly if you climate is very different or if your growing season is short. New Zealand is a great example. Some years, the tubers are almost all tan. Other years, they are almost all purple. And in still other years, they are intermediate. The only consistent thing is that they will turn fully purple with several weeks of exposure to sunlight. Varieties that undergo a significant change in color can be useful because it is an indication that the variety is reaching its maximum sweetness.