
Planting, Growing, and Harvesting Onions
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Onion varieties are categorized based on whether they’re “long-day”, “short-day”, or “day-neutral” varieties. This is because they are “photoperiodic,” meaning that hey grow in response to day length—the number of daylight hours needed to trigger bulb formation.
Short-day onions grow best in the southern United States, between 25° and 35° north latitude, and start bulbs when day length reaches 10 to 12 hours. The earlier that short-day onions are planted, the larger they get. In the South, onions can be planted in the fall and overwintered. Since they continue to grow throughout the winter, they will be ready for harvest in the spring.
Intermediate, or day-neutral, onions are best suited to the middle tier of U.S. states, approximately between latitudes 32° and 42°, and start bulbs when day length reaches 12 to 14 hours.
Long-day onions grow best in the northern states, between latitudes 37° and 47°, and start bulbs when day length reaches 14 to 16 hours.
Do not try to fool Mother Nature: Short-day onions planted in a long-day zone will result in small bulbs—not an early harvest.
Long-day varieties:
- ‘Yellow Sweet Spanish’: large, round shape; yellow-white.
- ‘First Edition’: high-yielding, stores well, flavorful, creamy-yellow
- ‘Red Wethersfield’: flat bulbs that store well, white flesh, red-skinned
- ‘Aisa Craig’, ‘Walla Walla’: huge bulbs
- ‘Buffalo’, ‘Norstar’: produce early but keep only until late December
- ‘Copra’, ‘Southport Red Globe’, ‘Sweet Sandwich’, ‘Yellow Globe’: keep well
- ‘Red Florence’: heirloom; 4- to 6-inch long, dark purple-red, torpedo shape; mild, sweet
- ‘Ailsa Craig’: heirloom; named for a Scottish island; large, up to 8 inches in diameter; average 2 pounds; pale yellow skin, globe shape; mild, sweet
- ‘Gold Coin’: cipollini; 1-1/2- to 3-inch yellow flattened bulb; pungent flavor sweetens when cooked
Short-day varieties:
- ‘Stuttgarter’: sold in sets, early maturity with a slightly flat shape, yellow
- ‘White Bermuda’: extremely mild, with thick, flat bulbs; white
- ‘Red Burgundy’: good table onion with mild, sweet white inside; short-term keeper
- ‘Crystal Wax White Bermuda’: a great onion for pickling when harvested at pearl size
- ‘Hybrid Yellow Granex’: sweet, Vidalia type
- ‘Red Creole’: heirloom; 3- to 4-inch, dark red globe shape; pungent
- ‘Southern Belle’: ruby color throughout
- ‘Texas 1015-Y Supersweet’: stores well
- ‘Yellow Granex’: Vidalia type; 3- to 4-inch, yellow, flattened globe shape; crisp; said to be the sweetest of the super sweet
Day-neutral or intermediate varieties:
- ‘Candy’: golden, thick-flesh, jumbo bulbs; stores well
- ‘Red Stockton’: large, red-ringed, white-flesh bulbs
- ‘Super Star’: large, sweet, white bulbs
- ‘Purplette’: mini onion, at 1-1/2 inches; glossy, burgundy red when raw; pastel pink when cooked or pickled; mild, sweet
- ‘Southport Yellow Globe’: early; 2-1/2- to 3-1/2-inch thick-skin yellow globe; mild, sweet
Cooking Notes
To make onions taste milder, soak them in milk or pour boiling water over the slices and let them stand for 20 minutes. Rinse with cold water.
Chopping onions can sometimes look daunting: There’s the skin and the layers… Where to begin? Check out our tips for chopping onions in four easy steps. Onion skins actually have several health benefits, too, so don’t throw them out!
Check out more tips on using onions in the kitchen and cooking them correctly.
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If you grow Spanish-type onions from seed they should be started indoors in February. If you can buy onion sets you can plant the small bulbs in the ground about the same time you plant peas. Spanish onions need long days to produce their bulbs. The onions will grow tops in cool weather and form bulbs when the weather warms.
I plant my onions in a raised bed bed approx. 4 ft. off the ground.my box is 10 ft. long and 6-7 in. deep.i plant my sets about 4-5 in. deep so that I get more of the white edible part of the onion. I use a hand trowel to remove them when it is time.been doing it that way for years. planted lettuce last year in the boxes to keep the rabbits from getting to it. if a rabbit jumps 4 ft. to get to my lettuce, he deserves it !!
All good ideas here that anyone who visits this page can benefit from. Thanks for sharing, Dale. (Sounds like the most work here is building the box!) Best wishes for a bountiful season!
I have a raised bed also, so did I understand you to say you plant your onion sets 4 to 5 inch deep? Everything I have read says only 1 inch but mine didn't do very well, so you might be onto something good. Also, do you water when you first plant them?
can you email me at tim.a.buell@culinary.edu to tell me how you built your box. I'm very interested in growing my own onions. thanks I go to the CIA right now and am very curious about the subject thanks!
Hi Tim,
Here’s a link to how to build a raised bed.
http://www.almanac.com/content/raised-garden-beds-how-build
Hi, am planning to start onion farming kindly advice me. Am from kisii Kenya
Hello. I live near Dallas TX and planted onion sets in March in a mature, raised bed. I was able to harvest and eat some of the 1015 sweet onions but the red onions wasn't worth bothering with. As an experiment I left some of the onions in the garden to stalk and flower. These flowers produced seed pods, dried out and have since produced small sets about 6-8" tall where the seed pods fell. It's now November 20 and I've harvested my fall crop of other vegetables and the only thing left are these mature, segmented bulbs from spring and these new sets. I'd like to have onions again in the spring. Should I leave them in the ground as is, dig them up and transplant now or dig them up and transplant in the spring? If I dig them up for spring, how do I care for them over the winter?
Over the years, I have had the same problem with red sets. Out of 100 red sets, I would be lucky to get 10 bulbs worth keeping. On the other hand, my yellow sets have always produced at least 90% yield. Does anyone have a trick to getting red sets to produce?
For advice for your climate, you might check out these pages from Texas A&M AgriLife Extension:
http://aggie-horticulture.tamu.edu/archives/parsons/publications/onions/ONIONGRO.html
http://aggie-horticulture.tamu.edu/archives/parsons/vegetables/SEED.html
Common onions are biennial, normally flowering the second year, although unusual weather flucuations may trick them into thinking it is time to flower that first year.
Note that if you grew a hybrid variety, the seeds may not yield plants with the same characteristics as the parent.