Source: Richard Jauron, Department of Horticulture,
Iowa State University Extension
In order to obtain the highest quality fruit, apples must be harvested at the proper stage of maturity. Once harvested, proper storage is necessary to maximize storage life.
The harvest period for apples varies from one variety to another. For example, Jonathan apples are normally harvested in mid to late September. The harvest season for Red Delicious apples is normally late September to early October. However, the harvest period for apple varieties is strongly influenced by weather conditions during the growing season. Gardeners, therefore, should base the harvest time on the maturity of the apples rather than a specific calendar date.
There are several indicators of apple maturity. Mature apples are firm, crisp, juicy, well- colored, and have developed the characteristic flavor of the variety. Red color alone is not a reliable indicator of maturity. Red Delicious apples, for example, often turn red before the fruit are mature. Fruit harvested too early are sour, starchy, and poorly flavored. Apples harvested too late are soft and mushy.
When harvesting apples, pick and handle the fruit carefully to prevent unnecessary damage. Sort through the apples during harvest. Remove and promptly use bruised or cut apples. Also, remove apples which exhibit insect and disease problems. Separate the apples by size and use the largest apples first as they don’t store as well as the smaller fruit.
Once harvested and sorted, store the undamaged apples immediately. The temperature and relative humidity during storage are critical for maximum storage life. Proper storage conditions for apples are a temperature near 32 degrees Fahrenheit and a relative humidity between 90 and 95 percent. Apple varieties, such as Red Delicious, stored under optimum conditions may be stored up to 3 to 5 months. Apples stored at a temperature of 50 degrees Fahrenheit will spoil two to three times faster than those stored at 32 degrees Fahrenheit. If the humidity during storage is low, apples will dehydrate and shrivel.
Small quantities of apples may be placed in perforated polyethylene (plastic) bags and stored in the refrigerator. Perforated plastic bags maintain a high relative humidity, while they prevent the accumulation of excess moisture inside the bags.
Apples may also be stored in unperforated polyethylene bags. Do not tightly seal the unperforated bags. Simply fold over the ends of the bags after the fruit has cooled down. Golden Delicious apples store best in polyethylene bags because of their tendency to dehydrate and shrivel. Most other apple varieties also store well in polyethylene bags.
Storage sites for large quantities of apples include a second refrigerator, cellars, unheated outbuildings, or the garage. Place the apples in polyethylene bags or plastic-lined boxes. The apples should be moved from unheated storage facilities prior to extremely cold weather as storage temperatures may drop well below freezing. Apples will freeze when temperatures drop below 30 degrees Fahrenheit. Frozen apples deteriorate rapidly once thawed.
If you have more apples than can be properly stored, the surplus can be dried, frozen, or canned.