Onions are a versatile vegetable that are grown worldwide and are a delicious staple in many dishes, such as soups and stews, and a flavorful addition to meats and sandwiches. Onions have been harvested in the wild for thousands of years by many indigenous peoples and are believed to have been cultivated as long as 5,000 years ago in China and India. In ancient Egypt, they were so highly esteemed, they had religious significance.
Proper selection, harvesting and storage of onions in the fall ensures that they will last well into the winter. In the cold dark days of winter, it is a treat to enjoy an onion from your own summer garden. Onions are categorized into two different types: short-day varieties which produce bulbs when the day length reaches 10 to 12 hours and long-day varieties that don’t develop bulbs until days are 14 to 16 hours long. Short-day varieties are higher in sugar content and are better suited to more southerly climates. Generally speaking, longer-day varieties are not as sweet, and have higher levels of sulfur, giving them a more pungent, as opposed to sweet flavor. These are the onions that cause you to cry when chopping. The long-day varieties, which do better in our climate, also store longer.
The optimum time to harvest onions is usually in the fall when the tops of the onion leaves begin to yellow. The yellowing is an indication the plant has reached maximum growth and is starting to go dormant. If the leaves do not fall over on their own, you can bend the tops to the ground. Wait about 24 hours and then you can start pulling them. Use a fork or other similar implement to loosen the soil under the bulbs, and then pull them gently from the ground by their tops. The plants can be shaken to rid them of excess dirt, but vigorous brushing or any kind of scrubbing can cause bruising which in turn can lead to rot.
Cure the onions before storing them in a warm dry place. Good air circulation is essential. Garage or shed floors work well. Keeping them out of direct sunlight will avoid sun scald. Lie whole plants-leaves, roots, bulbs- in a single layer and leave them to dry for 2 to 4 weeks. Onions are completely cured when the tops are dry and brown, and the skins rustle when touched. At this point, you can either cut the tops off or braid them together. Remove roots and lightly brush off remaining dirt.
Place onions in mesh bags or crates. Braided onions can be hung. Onions preserve best when stored in a cool, dark space where the temperature is between 32-40° F.
Onions with thick stalks that remain green and soft even after curing will not store well. An excellent way to keep them from spoiling is to caramelize them. Slow cook chopped onions in oil, add brown sugar and balsamic vinegar. When completely caramelized, the onions can be cooled, placed in freezer bags and frozen for future use.