Answer: Stachys lanata or lamb's ear is winter hardy into zone 4. It needs full sun and a well drained soil. (In heavy clay, it tends not to survive cold winters.) It also does best in a climate where the summers are not overly humid. In hot humid weather the foliage tends to decline, although the plants will survive.
If you are not able to find it for sale locally, you might be able to acquire a division from a gardening friend or you could order by mail from a source such as Bluestone Perennials.
Good luck with your search!
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