Musa basjoo is the hardiest of the bananas. In good soil with regular watering, they will grow from 1-foot tall seedlings in May to 10-foot tall trees in August. Once the foliage is killed off by a November frost, cut the stem down to around 4 feet and pile bags of leaves around. Be sure to cover all exposed areas of the plant. In spring, new shoots should emerge from the centre of the old stem as well as from the base. If not, you’ve had one impressive annual!