Onions
Dates below are counted from the average last spring frost or the average first fall frost. Enter a ZIP in the calendar for NOAA 1991–2020 station averages, or pick a zone and use the zone table.
When to plant
Soil and site
Fertile and ruthlessly weed-free — onions lose to weeds every time.
Seedlings
Sets are the easy path. In the South, choose short-day or intermediate-day varieties; day length is what triggers bulbing.
In the garden
Variety choice matters more than anything else you do. Steady water; ease off as tops start to fall.
Picking
When tops flop over on their own, pull and cure in an airy, shaded spot for 2–3 weeks before storing.
Harvest
First harvest is about 90–110 days after sowing or planting outdoors. The picking window often runs about 2 weeks.
When the tops fall over on their own, pull the bulbs and cure them in an airy, shaded spot before storing.
Preserving
Plain onions are not in the USDA vegetable canning guide. Cure storage bulbs, or use a tested pickle or the freezing method.
Freeze chopped onions with the NCHFP method. Frozen onions are for cooking, not for serving raw.
National Center for Home Food Preservation: Freezing onions →Pickled pearl onions are a tested boiling-water recipe. It does not cover canning plain storage onions.
National Center for Home Food Preservation: Pickled pearl onions →Dry sliced onions with the NCHFP drying guide, then condition them before packing.
National Center for Home Food Preservation: Drying fruits and vegetables →Canning, pickling, and fermenting notes here are summaries of tested USDA and National Center for Home Food Preservation methods. Times, pressures, and amounts live only on those pages. This site does not publish home-invented processing times.
Gear placeholders
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Dates by zone
These pages turn the same frost offsets into calendar dates for each zone the calendar covers.