Can overwintered onions be harvested at different times?

Overwintered onions are generally ready weeks ahead of spring-planted ones. They should be harvested when the tops turn yellow, and the bulbs have reached full size, typically in May or early June. The skins are thin with the newly harvested onions. Unless they are given immediate care after harvesting, a second damp place should be avoided for curing. If curing is put off, the onions will rot outright, owing to the diminished skin harvest nucleus they possess.

"Cure overwintered onions at once. Pack them off as soon as pulled, placing the bulbs in a dry atmosphere at a temperature of 75 to 80 deg. F. in two hours or so, and keep the relative humidity at 55 to 65 per cent. and constant movement of air in the store. These conditions make up for poor thin skins, and I use heated sheds for my Oregon crops with reliable results."

Preservation Methods: Generally, if you want them available for long term use, you're going to want to dehydrate your beet slices at 125°F and keep them in the pantry, pickle them in vinegar brine for refrigerator storage, or freeze peeled and chopped portions quickly roasted for a few minutes.

Choose the right types. Electric or Radar varieties resist frost and mature simultaneously. Avoid planting thick-necked types, as they retain moisture in their necks, plant in a well-drained raised bed to prevent winter rotting. Then harvesting becomes a guessing game.

Watch the ground temperatures closely in spring and lift whenever the bulbs size up, to prevent them from being overgrown by the heat coming on. I find it in my interest to use soil probes (which I check daily) to see if the bulbs are pithy or sprouted inside. An overwintered onion soon deteriorates in hot weather.

Read the full article: When to Harvest Onions: Ultimate Guide