Hi, all: Would someone like to suggest an answer: Which Oxalis are reasonably hardy? For me that means Zone 7. Every so often I buy Oxalis adenophylla from one of the suppliers who presumably buy them from Holland. They last five years or so then disappear. I don't think they freeze out, but they are gone. They do not set seed or otherwise multiply, just disappear. In pots, in the ground, in raised beds, various places, and so far none have been acceptable. Other Oxalis would be trialed if they were likely to be hardy. Ken western Oregon