Regarded by botanists as the world's tallest herbs, bananas (Musa spp.) may be colloquially referred to as trees, but lack bark and cambium. The large leaves and edible fruits evoke a sense of the tropics, but many varieties of bananas survive in warm temperate regions with winter temperatures that drop below freezing. Frost kills fruits, foliage and stems, but as long as the fleshy rhizome roots in the soil do not freeze, the banana plant will rejuvenate in spring. Uncut banana plant tissues shield the roots from harmful cold.
Banana Plant Basics
Banana plants only elongate and produce leaves from their growing tips at the ends of stalks. Cutting off or damaging the tip, including by winter cold, effectively ends the further growth of that stalk. Unhealthy yellowing or brown dead leaves may be pruned away to tidy the look of the banana. In regions where winter frosts don't occur, a banana plant remains evergreen but slows or temporarily halts growth. Subfreezing temperatures in winter initially kill all the leaves, and progressively kills the stalk or trunk tissues as temperatures sink further below freezing.
Pruning in Winter
The decision to cut down banana plants in winter depends on your aesthetic and the extent of winter cold expected in your region. If plants remain green, withhold harsh pruning until spring when warmer temperatures lead to faster regrowth. If only a frost occurs, the foliage burns, so only trim off rotting or unsightly leaves as needed. In regions where temperatures drop into the 10 to 25 degrees Fahrenheit range, all above-ground banana plant parts die, but the roots survive. Keep the dead trunk tissues intact to help buffer and insulate the roots and dormant buds from further exposure to cold the rest of winter.
In U.S. Department of Agriculture plant hardiness zones 7 through 9, where varying subfreezing temperatures kill back banana plants, do not fully cut back plants during the winter months. If the site of dead banana leaves, or slender barren stalks is too ugly, cut back cold-killed banana plant stalk to a height around 36 inches. The more stalk that remains, the more tissue that takes the brunt of drying winds and cold the rest of winter. The remaining above-ground tissues insulate the rhizomes, thereby shielding further plant harm. A 12- to 24-inch mulch around and over the plant base also gives protection from severe, harmful cold.
Ideal Pruning Time
Wherever banana plants grow and remain as perennials, withhold cutting back banana plants until spring. As air and soil temperatures warm, growth buds from the rhizome roots emerge and grow, as do the growing tips on healthy stalk tips in the banana plant cluster. Cut back unsightly or dead stalks after the threat of frost passes. In USDA zone 9, conduct the pruning maintenance in early to mid March. In zone 8, prune by mid April and in zone 7 by late April. The added sunlight exposure after pruning coaxes the banana plant to send up new shoots that much more quickly.