Most dry onions enter a period of dormancy after harvesting, which explains why they can usually be stored for several weeks; however, their keeping qualities do depend on the variety.
Strong onions that don’t have high water content, like yellow onions, have better keeping qualities than the white onion. Yellow onions keep for 2-3 months in a cool, dry place, while red onions only keep for 2-4 weeks. Don't store onions in the refrigerator. Their odour tends to spread to other food, and don't store with potatoes as they absorb their moisture, causing them to rot and sprout. A good way to store onions is to hang them in a basket in a well-ventilated, cool dry place. To freeze, simply peel and chop the onion, blanching is not necessary.