Thank you tyrlych very much for your reply. A friend from England gave me this plant. Is it an English plant? It is growing in my garden in Northern Spain, do you think it will grow well in a warmer climate?
It is cultivated everywhere now. USDA site shows it growing up to zone 8, and according to Flora Europaea it occurs in Grece and Italy, so why not Spain too. It does not like dry soil, so proper watering is impotant.