Answer: Asplenium Bulbiferum is hardy only in zones 9-11, where the lowest temperatures remain above freezing. You might be able to push the limits a bit if you plant in a protected place and mulch over the plant just before your first hard freeze. The easiest way to protect the plants is to place a wire tomato cage over the entire plant and fill it with straw or shredded leaves. Or, you could make cylinders out of chicken wire, large enough to surround the plant, then fill with mulch material. Don't use plastic of any kind - it will only serve to hold in moisture and promote fungal diseases.
Whatever foliage dies back during the winter can be cut off the plant in early spring. The roots should survive and produce new foliage in the spring.
Best wishes with your Mother Ferns!
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