The plant can be grown outside, unsheltered, as far north as Zone 8 in the United States and perhaps further north; above-ground growth is killed back by winter freezing, but the plant reemerges each spring in late May. The greatest impediment to producing a crop of seeds is the long maturation time for the seed pods – which is right up to the first hard freeze of the year. Waterlogging is indeed an issue – leading to root rot – and a well-drained sandy loam is preferred, but not essential.