Draba oligosperma

Matted perennial, 1 foot high, 3 feet across, Sierra Nev., 11-13,000 ft., this small perennial is doing fine at our 1800 ft. location, should be tried for miniature rock gardens, needs good drainage, poor soil. This one did fine for years here, but in the Dec. 1990 frost they froze out. It was -30 to -50 in their range but it froze here! They have snow when they're cold, we have open ground.