FYI - In USDA Zones 5-8, plant growth will die to the ground in winter (at 40°F additional growth stops and at 32°F the leaves die and tree can be cut back to 2-3'). Options for overwintering include: (1) For plants grown directly in the ground, cut stems back to 2' after frost kills the leaves, wrap stems with burlap, bubble wrap or plastic and apply a thick mulch to the ground to protect the roots; (2) For container plants, bring container indoors in fall before first frost and place in a large sunny room for overwintering as a houseplant, with reduced water and fertilization, or trim foliage and store container in the basement in a cool frost free corner, providing just an occasional touch of moisture in winter to prevent the soils from totally drying out; (3) For large plants (whether grown directly in the ground or in containers), cut foliage back in fall after first frost, trim plus wrap roots in plastic and store plants in a cool, dark, frost-free corner of the basement until spring.

FWIW - I do option 3, live in 7b.

An established. M. basjoo in zone 7b doesn't need much protection. One lazy but effective way would be to let the stalk and leaves collapse onto the crown after several hard freezes, then remove the dead foliage in spring. Otherwise you can remove the pseudostem close to the ground and cover with a couple feet of straw or similar mulch. Some people make a special effort to wrap the pseudostem with the aim of preserving it through the winter, but it doesn't make a lot of difference in growth the following year.