Answer: This plant is quite winter hardy when grown in the ground, however in a container the roots are exposed to more cold than they would be if insulated in the ground. You might try heaping mulch around the sides of the container to insulate it, but wait to do that until extended freezing weather occurs. Take care to water it if needed during the colder months. The soil should be kept slightly damp (not saturated, just not bone dry) whenever it is not frozen. You may find that the plant has exhausted itself this season and needs to be divided next spring.
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