Here are my tips for growing great onions:

Site, soil type:

Plant onions in soil that has medium fertility; not real rich, but not void of nutrients either.

Plant in soil that is light and well drained.

Onions like plenty of sunshine.

Planting requirements:

Start bulb onion seeds indoors in January for planting outdoors when soil can be worked.   Plant eight inches apart.

Plant green onions outdoor when soil can be worked.  Sow seeds ½ inch apart and 1/8 inch deep.

Nutrition/Fertilizer needs:

Before planting add 1 cup organic fertilizer per 10 foot row.

Water needs:

Ensure plentiful, even moisture.

Other tips:

Onions are good at repelling pests, due to their odor.  Plant them throughout the vegetable garden.

For storage of onions – When onion tops begin to dry out and fall over, push the rest of the tops over.  Wait a week and dig the bulbs.  Spread bulbs out in the sun to cure for a week to toughen the skins. Store in a dark room at 55 degrees.

Onions regulate their stages of growth by the amount of daylight.  A significant amount of light available early in the season will produce larger bulbs.   Long day varieties (described as such in the seed catalogs) should be planted above 36 degrees latitude.  Short day varieties should be planted below 36 degrees latitude.

36 degrees for onions

The graphic above shows the 36th parallel.

“Missouri Compromise Line” by Tintazul: Júlio Reisderivative work: JWB (talk) – US_Secession_map_1865.svgFile:Blank US Map.svg. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Missouri_Compromise_Line.svg#mediaviewer/File:Missouri_Compromise_Line.svg