Lewisias grow in mountains in NW-America, in screes where they are covered in snow all winter. They don't tolerate wet winters well and need exceptionally good drainage to survive the wet winters in S-Iceland. My experience is that they have the best chance of survival growing in rock walls, as close to being vertical as possible. They are also well suited to growing in pots, which are stored sheltered from the rain during the winter months. Columbian lewisia is a small alpine with reddish purple flowers.