Yacon is a plant of the middle elevations of the Andes. It yields best in milder climates with a summer of seven months. The optimum temperature for growth is about 65 to 77′ F (18 to 25’C), but yacon tolerates temperatures as high as 104′ F (40’C) as long as sufficient water is available. Dry conditions and wind reduce the maximum temperature that yacon can tolerate.
Yacon is a heavy user of potassium and so benefits from fertilizers that are potassium rich. It has only moderate nitrogen requirements, which are best served by making sure that your soil is rich in organic matter. Too much nitrogen can reduce root growth. The phosphorus requirement is fairly low and will generally also be met by soils that are rich in organic matter such as finished compost. Yacon tolerates a wide range of soil pH, but seems to perform best in weakly acid soil (6.0 to 6.5 pH).
Yacon plants are usually started from pieces of the parent plant’s subsurface crown of dormant rhizome. They store best in soil, but they aren’t particularly frost resistant, so it is best to keep them safely indoors until after your last frost. Although they may keep in a cool, humid environment until planting time, it is safer to pot them until you are ready to plant. Keep them under 50′ F (10’C), if possible, until about a month before planting time; then, warm them up and give them some light. Yacon dormancy is not very strong, so the propagules may sprout. Just pot them if you can’t plant them out immediately and put the plant where it can get at least some indirect sunlight. Transplant after your last frost. Plants with a few sets of leaves transplant better into cold, wet ground than dormant propagules do.
Yacon starts growing slowly, particularly in cool soil. Yacon is particularly vulnerable to frost; it is typically damaged even under very light frosts that leave other frost-sensitive plants undamaged. While it can recover from a light frost, it is going to take the entire season to form tubers anyway, so there is no advantage to early planting.