Onions: from seedlings to storage
Onions are a member of the allium family and are cousins of garlic, chives, leeks, and shallots. Onions are biennials which means they grow vegetatively the first year, then bloom the second year. The following are some varieties of onions:
Slicing onion: white, yellow or Spanish
Purple onions: have a mild sweet taste
Scallions or green onions: grown for their long stem and have little to no bulb
Pearl onion or pickling onions: usually small white and used for pickling
Shallot: mild tasting with a very small bulb
Leeks: Like scallions, mild but with a distinctive taste, the entire stalk is eaten
Vidalia onions: defined more by where they are grown than the variety
Onions first form a top and then depending on the variety and length of daylight, start to form the bulb. The size of the onion bulb is dependent on the number and size of the green leaves on top. For each leaf there is a ring of onion. The larger the leaf, the larger the ring will be. Onions are classified as long day onions or short day onions. Long day onions begin to form bulbs when there are 14-16 hours of daylight and are the best type of onion to grow in the northern states. Short day onions begin to form bulbs when there is 10-12 hours of daylight and are grown mainly in the southern states.
Onions are hardy plants, frost and freezing temperatures, and even snow will not kill them. It only slows their growth until warmer temperatures return. However, extended temperatures of 20-25 degrees will kill them.
You can start onions from seed in your home in late winter. However the most common way to grow onions is to buy seedlings or sets. Sets are onions that were planted from seed from last year. They look like a small onion about the size of a marble and come in varieties that are white, yellow, or red. Since this is their second year of growth they want to form seed heads. This hard seed stalk emerges through the center of the bulb and this is why onion sets do not last as long as onion seedling. The onion bulb which is penetrated by the seed stalk is hard when you harvest the bulb, but will prematurely decay, causing the loss of the entire bulb in storage. If you are storing onions, onions from sets need to be used first.
Seedling are small green onion plants with a tiny bulb which have been grown from a seed this year. They are usually in a mass and have to be carefully separated into the individual plants when they are planted. Onion seedling do not usually develop a seed stalk because this is their first year. Seedling are the best type of onion to store. Both onion set and seedling need to be planted out when spring temperatures reach around 48 degrees, and planted so there is 3-4 inches between each onion.
Onions are edible at any stage and immature bulb-forming onions can be thinned from the garden row and eaten. Harvest onions in late August to mid-September. It is time to harvest when 50 percent or more of the onion tops have fallen over. Gently push down the other plants, taking care not to break the stalk. Leave the onions in the ground for several days, then pull them and let them cure in a warm, airy place out of the elements for a week or two. Onions should not be left in the ground if there is a lot of rain in late summer, because they may begin to rot in heavy wet soil.
When properly dried for storage, onions will have a dry, shrunken neck and dry out skin. One thing you can do is to braid their tops together and store them in a cool dry place. Or you can cut off the dried tops and roots and let them air dry for 2-3 days to seal onions and avoid pre-mature spoiling. Than they can be stored in a mesh bag or nylon stocking. Place onion in nylon stocking or mesh bag, tie a knot between each onion, or use a plastic tie between each onion. Continue until the stocking is full. Loop the stocking over a rafter or nail it to the wall of a cool, dry building. When an onion is needed simply clip from the bottom, with a scissor or remove the plastic tie.
Another suggestion is to spread onions on a screen which allows adequate ventilation. Onions should not touch each other. The sweeter the onion, the higher the water content and the less shelf life, strong pungent onions will store longer.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.