For one of the best remedies for killing weeds and grass where they shouldn’t be growing, start by wetting the soil so that it is moist but not overwatered. Next, sprinkle a teaspoon of baking soda over the top of the entire weed, including the leaves and the soil surrounding the base. Banana leaves will burn at the slightest frost and though they might look dead to you they should be just fine. At this point just let the dead leaves hang on the plant to provide added protection to the stocks and as soon as it warms back up and you start to see a new leaf emerge then cut off all the dead leaves.