Answer: If you are asking about a perennial plant or shrub to be used as a permanent ground cover, the answer would depend on the type of planting location and on what is available for planting in the fall in your area. Many shrubs can be planted in the fall, as can perennials. Take care to water as needed to keep the soil moist but not soggy until it freezes, and use several inches of organic mulch to help protect the newly establishing roots from heaving during the freeze thaw cycles.
If you are asking about a plant to use as a cover crop or living mulch application, you might look into annual rye grass. This would be used as a temporary means of protecting the soil from erosion over the winter and would then be dug or tilled under in the spring. Any organic mulch (double shredded bark, straw, chopped leaves, etc) could also be used for the same purpose.
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