Fruits That Need to Ripen After Harvesting
One of the reasons gardeners have backyard orchards is to be able to harvest tree-ripened fruits at the prime of ripeness and taste. Apples, oranges, peaches, apricots and plums all fit into this image. However, some fruits like pears and avocados will never ripen properly if left on the tree, and picking them is necessary for ripening. In others, such as mangoes and bananas, picking mature but unripe fruit is a necessity of getting it successfully to market. These fruits will ripen if left on the tree, but their shelf life is then so short that they can't be shipped.
Ripening is a complex process based on changing starches into sugars, breaking down fruit acids and developing aromatic compounds characteristic of the particular fruit. The gas ethylene triggers fruits to ripen by signaling the fruit to produce enzymes, which are chemicals that act as catalysts to break down the starches and acids. Commercially, mature but unripe fruits are treated with ethylene gas for a specific amount of time to begin ripening. At home, putting the unripe fruit in a paper bag with an apple or a banana, both good sources of ethylene, hastens ripening.
It's hard to tell by looking at an avocado (Persea americana) still on the tree if it is mature enough to be picked. Green-skinned varieties don't change color when they're ripe, but "Haas" changes from green to black. Commercial growers take samples to analyze the fruit oil content so they know when to harvest. You can just pick a fruit or two, put them inside where they don't get direct sun, and see if they ripen within three to 14 days. If they don't, repeat the ripening test. When the avocados ripen well within this time frame, you know the fruits are mature and can be picked. If you want speedier ripening, put avocados in a paper bag. For fastest ripening, add an apple or banana to the bag. Avocados grow in U.S. Department of Agriculture plant hardiness zones 10 through 11.
European pears (Pyrus communis) ripen best off the tree. If left on the tree, the ripening begins at the center of the fruit, leaving it mushy by the time the exterior is ready to eat. After picking, pears need chilling at 30 degrees Fahrenheit for a day or two for "Bartlett" pears and two to six weeks for "Anjou," "Bosc" and "Comice" pears before they are ripened at 75 degrees Fahrenheit. Asian pears (Pyrus pyrifolia) ripen satisfactorily on the tree. Both European and Asian pears grow in USDA zones 4 through 9. Kiwifruit (Actinidia deliciosa) can be harvested when it is mature -- the seeds will be black -- and ripened after picking. Refrigerate the fruits up to several months and ripen them as needed. Kiwifruit grow in USDA zones 7 through 9. However, hardy kiwifruit (Actinidia arguta) grows in USDA zones 4 through 8, and fruits will ripen on the vine.
Bananas and Plantains
Commercial bananas (Musa acuminata) are picked green for shipping, but even in home orchards bananas are picked when the fruit is full-sized but about seven to 14 days away from being ripe. Plaintains (Musa paradisiaca) are hybrids developed primarily for cooking and used when their starch content is still fairly high. However, they can be ripened and eaten as a fresh fruit, with ripening taking three to four weeks. The skin turns completely black and the fruit becomes soft. Plantains grow in USDA zones 8 through 11. Bananas and plantains grow in USDA zones 8 through 11.
Mango (Mangifera indica) is an example of fruit that ripens on the tree but is picked mature-green for marketing. In USDA zones 10 through 11 where mango is hardy, you can leave your mangoes on the tree until the skin turns from green to yellow, red or orange, depending on the cultivar. Then pick one and cut it open to see if the flesh next to the seed is yellow. If it is, the mangoes will be ripe in a week, when you can pick and refrigerate them; if birds and backyard wildlife threaten your crop, pick them early. Guavas (Psidium guajava), hardy in USDA zones 9 through 11, come in different varieties. You can allow them to ripen on the tree or pick them when mature-green as commercial growers do and ripen them at room temperature using the paper bag method.
- University of California Cooperative Extension Ventura County: Harvesting Avocados
- Urban Harvest: Gardening Advice: Mexican Avocados
- California Avocados: How to Choose and Use
- Oregon State University Extension Service: When to Pick and How to Ripen Pears to Perfection
- PickYourOwn.org: Pear Facts and Picking Tips
- University of Illinois Extension Hortanswers: European and Asian Pear
- Oregon State University Extension Service: How to Harvest and Store Kiwifruits
- University of Florida IFAS Extension: Banana Growing in the Florida Home Landscape
- Raw Food Health: How to Ripen Plantains
Cathryn Chaney has worked as a gardening writer since 2002. Her horticultural experience working in the nursery industry informs her garden articles, especially those dealing with arid landscaping and drought-tolerant gardening. Chaney also writes poetry, which has appears in "Woman's World" magazine and elsewhere. Chaney graduated from the University of Arizona in 1992 with a Bachelor of Arts in English.