maihueniopsis darwinii Cold Hardy Form

Maihueniopsis darwinii or Darwin's Brittel Cactus is a native to the Patagonia steppe in South America. Plants have been grown at our local nature center in Pueblo, Colorado and several growers have in Denver. They have taken -11F with no issue and seem to be one of the first cactus to bloom in the garden. Plants do break off easily and have long spines to attach to you. Expect to get broken plants due to transit. But they root easily.
 
I do not guarantee these in a zone 5/6 because everyones growing conditions are different but this would be a good trial plant to grow in your cold outdoor garden. Try to plant outdoor 90 days before 1st hard freeze.