Yacon plants grow up to 2m and have big, arrow-shaped leaves which are apparently also edible (I haven't tried them yet).
• obtain a yacon crown or a couple of rhizomes from a friend, or have a look on the internet for folks selling the crowns.
• keep your crown divisions indoors in a large paper bag in a dark place, a bit like seedling potatoes. In early spring, set them out in a cardboard box, again in a dark place where they will start to sprout like crazy.
• yacons need room so space them 1m apart, burying them 15cm down under a mound of earth with a generous helping of compost/mulch on top.
• yacon plants are almost completely pest and disease-free so you can just about plant and walk away, watering only when it is very dry.
• harvest after the first autumn or winter frosts by gently raising the crown and tuber with a fork.
Although gardening books and internet sites often say not to expect a huge crop from yacon in the first year, I have found that if I dig over the soil really well before planting the rhizome clump and add a good quantity of compost, I can get 1-2 buckets of tubers after the first 12 months. They do an excellent job of aerating the soil and breaking up clumps, leaving a lovely tilth wherever I plant them.
The yacon plant.