Prevent damage from animals to your bananas as they grow and ripen on the plant. Bananas left exposed become damaged from sunburn, the rubbing of the large leaves against the fruit and from scavenging animals. Over the years, banana growing regions have honed a procedure for cheaply protecting bunches of bananas on the tree until ready for harvest. In Queensland, starting in 1955, blue-tinted polythene bags came into use for protecting bananas followed by wrapping the bunches in "High Wet Strength" kraft paper bags in 1963, according to Purdue University. For the most effective protection, New South Wales recommends using polythene bags to protect the fruit and increase the production yield.
Look for signs of emerging banana bunches. Wait until two to three weeks after the bract emerges from the top of the tree and the bracts pull away from the fruit. The Banana Consultants recommends waiting two weeks. Some banana plants might take three weeks until you can put the cover on, according to Purdue University.
Climb a ladder, if it is needed to access the banana bracts. Pull an opaque bag, such as burlap or a specialty blue-colored polythene bag, over the entire bunch.
Tie the top of the bag closed by wrapping a string around the bag at the top of the banana bunch.
Leave the bag in place until after harvest, between 75 and 80 days after putting the covering over the banana bunch, according to Purdue University.
Cut the stem attaching the bunch of bananas to the plant with a machete when ready to harvest. Rub the remnants of the flowers and harvest when they crumble easily, the bananas turn to light green and the fruit begins to straighten in shape, according to Purdue University.
Allow the bananas to continue to ripen off the tree at room temperature, until yellow and speckled with brown. Leave them inside the banana bunch covering to hasten ripening.