If your friend has these he /she should know where they came from Jes. They are very tricky plants to grow in most of Europe.
They rot very quickly if they get wet when the weather is hot. They do not like root disturbance. Plant on gritty soil like Fred said. Cover the rhizomes with 2 or 3 cm of gravel. Grow in full sun. Water when you plant them, then dry out before winter gets cold. Water again when they start to grow in the spring. Dry in summer. Full sun.
It is important to cover the rhizomes with gravel. If you cover them with soil or compost instead; they are more likely to rot.
Aphids can also kill them very quickly!
