Make sure your soil will work for Yacon. It needs consistent moisture and moderate heat. The plants themselves need a long growing season, six or seven months, before tubers can form in the fall. These plants might not do well in extremely cold areas as they are frost tender.
Order small potted plants to place in the ground or start your own indoors in the spring by dividing crowns of existing plants with tubers. Place the plants about 3 to 4 feet apart, add compost and water when dry. Yacon can grow to 5 to 7 feet tall but will only produce little yellow flowers in warmer climates.
Be patient. Harvest won't come the first year because Yacon needs to adjust to the weather. But after they do, look for a great harvest - nearly triple that of potatoes. With general care, you'll have a plant that's almost pest and disease free.
Place straw around the base of the plants in early fall, before the first frost, to protect the tubers. Don't harvest the tubers and crowns until the first frost has killed off the upper parts of the plants, but do it before the ground has frozen. Then remove the entire root system from the ground, take the tubers from the crowns and place them in the sun for a couple of weeks.
Store the crowns indoors in peat moss or loose in tubs like you would potatoes until early spring. Then you can split apart the sections that have green buds and plant each one in its own pot as new plants for next season. Yacon tubers store well in a root cellar or cool, dry basement where their sweetness naturally increases. They can be eaten for up to 8 months after harvest.