Position: sun-partial shade; Soil: fertile, well drained; Rate of growth: fast-growing; Harvesting period: late November and December; Hardiness: half hardy (will need protection from frost) This tuberous vegetable was first grown in the Andes, but they are now becoming increasingly popular throughout the world – partly because of their versatility and resistance to disease, but also because of their flavour. They have a crisp and juicy flesh that has a lemony tang when eaten raw, but they can also be cooked (like a potato) and then they will have a nuttier flavour and a starchier texture; Garden care: You can start these tubers off in pots filled with a good, general-purpose compost in April or May, and keep them in a frost-free spot – an unheated greenhouse or cool, bright windowsill would be ideal. Then, when all risk of frost has passed, plant them out (around 8cm deep and 1m apart), and initially protect them with a layer of frost fleece until they them with a layer of frost fleece until they have hardened off fully and the surrounding soil has warmed up a little. Alternatively, the tubers can be planted straight out in situ in late May or early June. Keep the palnts well watered and apply a general-purpose fertiliser throughout the summer. The underground tubers will develop in the autumn, and the time to harvest them is after the foliage has been completely knocked back by a hard frost in November or early December.