These plants easy to cultivate and will grow best in temperate areas. They are very hardy and also very easy to propagate. Even a small piece of tuber will grow if left in the ground making this hardy plant a potential weed. They will also tolerate a wide variety of soils and require medium nitrogen levels. Because of their tall stature they may also be planted as a windbreak screen.
Plant tubers as soon as the soil is workable in spring. Cut the larger tubers into pieces making sure each piece has several buds and plant whole the ones that are the size of a hen’s egg. Make a drill and plant the tubers about 12 cm deep and 30 cm apart. Cover them with soil. When the plants reach 30 cm tall you should earth them up for stability to half their stem height. In late summer cut the stems back to 1.5 m removing any flowerheads in the same time. If you are growing them in a very exposed site you should stake or support their stems. Water the plants in very dry conditions. When the leaves start to yellow you should cut the stems back to just about the ground level.
Harvest the tubers about 16-20 weeks after planting making sure to not damage the roots as every piece of it will grow to a new plant next year. Lift them only when you need them as they will keep best in the ground. Save some tubers for replanting them or if you want to grow them in the same place the following year just leave some tubers in the ground. If you do not want to grow them anymore you must remove even the small tubers as they rapidly become invasive. If you live a sever climate or you have a heavy ground then is best to lift the tubers in early winter and store them in a cellar or in clamps outdoors for up to five months.