If you cut it down to 12" in late fall, piling chopped or shredded leaves over the top should be all you need. It will die back every winter in zone 5b but is reliably hardy. Use the lawn mower to chop/shred some leaves to mulch the crown. Covering with a terra cotta pot makes sense except it will be prone to cracking as it absorbs moisture then suffers freezing temps. Freeze and thaw cycles have ruined many clay pots.
Answered on June 4, 2018
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