Onions, Bulbing

What to Plant:  Seeds, Seedlings, or Sets
Dates:  See Vegetable Planting Calendars
Season: Cool
Group:  G9
Rotation:  Root
Edible:  Bulb
Nutrition:  Vit C, B6, Manganese
Seeds/oz:  6500 – 8500
Seed Viability:  1 year
Soil Temp:  45 ºF – 95 ºF (75 ºF)
Planting Depth:  Seed:  1/4″ – 1/2″, Transplant: 1″ – 1.1/2″
Germination:  10 – 14 days
Spacing: 4″ – 6″
SqFt Spacing:  9
Days to Harvest:  7 – 8 months from seed; 3 – 4 months from transplant
Length of Harvest:  Onions have a long harvest period since they can be harvested at every stage from pencil size to fully developed bulbs.
Origin:  Central Asia, West Pakistan, Iran

Bed prep:  All onions like a well-drained, loose, fertile soil.  Prepare the soil 8″ – 12″ deep.  Add compost and fertilize with 1/4 to 1/2 cup of your favorite SROF and a bit of greensand before planting.  I use about 1/3 compost to garden soil and start out with 1/2 cup of SROF and about 1T of greensand per square in my square foot beds.

Planting:  Onions can be planted as seedsseedlings, and sets.  Each has a different planting method.  For planting details, click on the links.

Watering:  Once a week without sufficient rainfall.  Onions prefer well-drained soils and do well in raised beds.

Aftercare: Keep bed free of weeds – mulch.  Do not cultivate deeply as you may damage the roots or bulb.  Watch for disease or pests.

Harvest:  Onions can be harvested at several stages – as green onions once they reach pencil size, as small spring bulbs, or once they have matured as large bulbs.  At maturity the leaves will begin to yellow and fall over.  It is not necessary to bend the leaves over manually.  Unless you need the garden space, onions can be harvested as they are needed from April – June, but harvest within a month of yellowing or when 3/4 of the leaves have fallen over after which they should be dug, cured, and stored in the refrigerator for the longest storage.

Onion Pests:  Thrips – sucks nutrients; mulch to keep soil cooler, keep soil evenly moist but not soggy, apply additional fertilizer to build up the plants, spray with Spinosad.  Onion fly – feeds on roots; manage with crop rotation.

Additional Information:  Gulf Coast gardeners must plant short day varieties.  Check the seed packet for day length info and buy only known varieties of seedlings or sets.  Most onions labeled only “red”, “yellow”, or “white” will not bulb well here.  Read more about day length here.

Onions should be cured after harvest.  Dig or pull the onions on a dry, sunny day.  Lay the freshly dug onions out in a sunny place to stop the roots from growing and kick start the curing process.  After a day or so, spread the onions out in a dry, shady location and allow them to dry until their skins rattle.  This can take 2 – 3 weeks.  A shady porch or garage floor covered with paper is a good location.  It is not necessary to trim the leaves, but if you wish to do so, leave at least 1″ so the onion will seal itself off at the top.  Use any onions with damaged or soft spots first.

History:   Onions have been in cultivation for at least 5000 years and may have been one of the earliest crops in cultivation.  They were used for food, medicine, and in ceremonies.  Onions could be dried for easy transportation and later use. Egyptian pharaohs were buried with onions, a symbol of eternity with their circle-within-a-circle structure.  Onions are mentioned in ancient Chinese, Sumerian, and Indian writings.  Greek Olympians fortified themselves with a diet of onions before the games.  The Romans carried them on their conquests.  The earliest Pilgrims brought onions to the New World and planted them as soon as land was cleared.  They later found that onions grew wild and had been used by the Native Americans for food, medicine, and as a dye plant.  Read more about the history of this important food plant here.