Bananas are a tropical herb that can grow stiff stems that resemble trunks. Tolerant of light frosts and freezes, the above-ground parts of a banana plant can recover from a cold spell and continue growing immediately if weather warms.
Removing plant parts on cold-damaged bananas depends on the climate, particularly if more frosts may be encountered in the winter before consistent warmth returns in spring. Always immediately remove soft, rotting or smelly leaves or stems of bananas hit by cold, but retaining the dried stem and foliage can actually protect the banana from further cold damage.
Determine the extent of the freeze damage on the banana. Light frosts, with temperatures down to 31 to 33 degrees Fahrenheit may only cause some leaves to brown and dry. Freezes, when temps dip into the 20s, will fully kill back foliage and stems. Prolonged exposure to cold eventually kills the thick stem of the banana.
Consider leaving cold-damaged leaves and stems on the banana plant so that they dry and drop off the plant naturally. Leaving the damaged tissues that dry helps protect the core of the banana plant, namely the growing tips or root crown when freezes are numerous.
Prune away rotting, soft leaves, stems or other tissues with a pruners, loppers or machete. Rotting tissue usually smells bad and should be cut away so the rot or disease does not further infiltrate into the plant.
Investigate the date of the last expected spring frost or freeze is for your region. Pruning the banana back now to tidy it and encourage new growth is not a good idea if it is still winter and another frost or freeze could likely occur.
Trim back the banana plant fully once the danger of frost has passed. SInce bananas are fast growing, many gardeners choose to chop off all frost-damaged or unattractive trunks of bananas with a loppers or machete blade in spring so the new growth comes back quickly and robustly.