You can keep many varieties of apples for up to six months if you store them properly. Red Delicious, Golden Delicious and Jonathan are all excellent candidates for long-term storage. Avoid trying to store early ripening varieties such as Lodi apples, if possible. These might go bad after as little as a week even with proper storage. The two most important factors to consider when storing apples are the humidity and temperature, so an accurate thermometer and humidity sensor are vital if you wish to store apples successfully.
Sort through the apples you wish to store. Remove any that show signs of damage, such as bruising, cuts, scratches or holes. These apples are not good candidates for storage. You can discard them or use them to make apple products that you can then store, such as apple juice or apple sauce.
Place the apples into the polythene bags. These bags will help maintain the correct humidity level, which ideally should stay between 90 and 95 per cent. Fold the ends of the bags under the apples, but do not tie the bags completely shut. Keeping the apples in an airtight bag can cause carbon dioxide to build up in the bag, leading to spoilage.
Store the bags of apples in a cool, dark place. For the longest storage, you should keep the apples at -1.11 to 0 degrees Celsius. Apples do not freeze until their temperature drops below -1.44 degrees C, so maintaining a temperature slightly above that is crucial. If you do not have the resources to store the apples at this precise temperature, simply put them in the coolest, darkest place you can find that never drops below -1.11 degrees Celsius. This might be a root cellar or a basement. Ideally, the temperature should not rise above 4.44 degrees Celsius.
Check the temperature and humidity levels of your apples every two to three weeks to ensure that the storage environment is still ideal.
Remove any apples that show signs of spoilage to prevent them from contributing to faster spoilage of the entire group.
Do not store McIntosh apples at -1.11 to 0 degrees Celsius, as this might lead to brown streaks within the apple. The ideal storage temperature for this variety is 2.22 to 3.33 degrees C.