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Growing onions in home gardens

A quick guide to onions

  • You can grow onions from seed, transplants or small bulbs called “sets.”
  • Plant onions early in spring.
  • Soil for onions should be well-drained and high in organic matter.
  • Onions are shallow-rooted and require constant moisture for proper growth.
  • Harvest onions when about half the tops are falling over and dry.
  • Curing is essential if you want to store onions. You must dry them in a warm, dry, well-ventilated area.
Person holding freshly harvested onion.

Long-day and short-day onions 

Onions (Allium cepa) have relatives that include garlic, chives, leeks and shallots.

Storage onions grown in Minnesota generally are “long-day” types that require 14 or more hours of daylight to form bulbs. All onions require full sun for best growth. Overcast skies and cool temperatures during the growing season will delay bulb formation.

Sweet or mild onions are "short-day" onions. Although you can grow them in Minnesota, they will generally develop small bulbs. Bunching onions, including scallions and Egyptian walking onions, have green stalks.

Soil pH and fertility

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Planting

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How to keep your onion plants healthy and productive

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Cindy Tong, Extension post-harvest horticulturist 

Reviewed in 2018

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