Onions can be stored for at least 6 months and even longer by harvesting them at the right time. Farmers should be careful during harvesting the crop. And when the stems of the plants dry up to 15 to 20 percent and start to break, then the delay in harvesting of onions should be avertd. Because the longer the onion is harvested, the greater the risk of crop rot. ‘Thick-stemmed bunches of onions that are not fully ripe should not be stored.