When you are growing your own bananas (Musa spp.) it's important to know how to ripen them to perfection. Ripening requires a precise balance between ethylene gas, temperature and storage conditions. Sunlight is less of a factor, but it does play a role in the ripening process. If you want to grow bananas, you will likely have the greatest chance of a fruitful harvest if you live in U.S. Department of Agriculture plant hardiness zones 9b through 11.
Harvest homegrown bananas while the fruit is still green and unripe. This gives you more control over the ripening process, producing better-flavored fruits. The green bananas are composed mainly of starch, but the ripening process converts those starches into sugars, which is why fully ripe bananas taste sweet.
When the bananas are mature, but still green on the plant, they begin to produce ethylene gas, which is a naturally occurring hormone from the plant that triggers the ripening process. Ethylene gas production doesn't depend on sunlight because bananas will still produce it if sealed in opaque bags. The riper the bananas become, the more ethylene gas they produce. A balance between the fruit's temperature and ethylene gas amounts is used to achieve predictable ripening. Ethylene gas produced by the bananas is trapped around the ripening fruit by bagging bunches of bananas in opaque bags. If you want to trap more ethylene gas and speed ripening of your home-picked bananas, place the fruit in a paper sack with a fully ripe apple, which produces the ripening gas, but do not use "Granny Smith" or "Fuji" apples.
During the ripening process, you should keep your bananas out of sunlight, but the light is not the reason for this. The heat from the sunlight is what affects the ripening of the bananas. Leaving bananas to ripen in direct sunlight raises the temperature of the fruit. When the fruit is warmer, it ripens faster, and it may become too soft, too quickly, resulting in bland-flavored fruit. Fruit temperatures above 68 degrees Fahrenheit are most likely to create this situation if the fruit is exposed to ethylene gas.
The temperature is important for the ripening of bananas. If it is too cold, the fruits may get injured, which occurs when the fruit itself reaches 53 F. Temperature control is also important to keep the bananas from going from green to mushy and overripe. If stored above 74 F, which can happen with the warming effects of the sun, the fruit's shelf life drops to four days or fewer.
- University of Hawaii: Banana Ripening: Principles and Practices
- University of California Cooperative Extension: Banana Ripening
- University of California Davis Postharvest Technology: Questions and Answers: Do Bananas Respond to Ethylene Gas Below 16 Degrees C?
- University of Florida IFAS Extension: Musa Spp.: Banana
- University of California Davis Postharvest Technology: Questions and Answers: Why Do Some Fruits Ripen on the Tree and Others Ripen After They Are Picked?
- University of California Davis Postharvest Technology: Storing Fresh Fruits and Vegetable for Better Taste
- Texas A&M AgriLife Extension: Banana
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