How to Grow Onions from Seed

comments (12) March 10th, 2009

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Click To Enlarge Photo: Lynn Karlin

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Into the ground they go
If you are fortunate enough to have a garden you can work  early in the season, you may opt to seed your onions directly in the ground. I generally set out my transplants (also sets if I have any) mid-May, when they’re about half the size of a pencil.

Whether growing from seed, set, or transplant, onions need soil that is high in organic matter and well drained—no standing water after a rain. Onions prefer fertile, loose loam with a pH of 6 to 6.5. I work in a 5-10-5 fertilizer or ProGro 5-3-4, an organic fertilizer, depending on what I have on hand.

I transplant the seedlings 1⁄2 inch deep, 4 to 6 inches apart. If the mature bulb is large, I give it 6 inches; if smaller, 4 inches is adequate. Once they’re in the ground, I cut the top-heavy leaves back to 6 inches. I plant some varieties closer and thin them as summer progresses. I use thinned onions in salads and cooking.

Transplant into the garden
Transplant onion seedlings into loose, fertile loam, spacing them about 6 inches apart.
 

I used to plant single rows of onions. This year, though, to conserve space, I planted double rows 8 inches apart, with 1 to 2 feet between the double rows. Plant­ing in rows, as opposed to beds, cuts down on maintenance, because rows are easier to weed. I keep onions well weeded to avoid competition for light, water, and nutrients. And I pull weeds by hand to avoid damaging the shallow onion roots.

  Brush soil away from the base
  As the onion matures, brush soil away from its base so it perches on top of the ground. Here, the roots of 'Ailsa Craig Exhibition' firmly anchor it to the soil.
   
Water and nutrients are an important part of onion growing. The soil surface should be evenly moist. I give onion plants at least 1 inch of water a week, and make sure there is a constant supply of moisture during the bulb-enlarging stage. If it’s too dry and plants are grown under stress, the bulbs will be smaller and have a stronger flavor. If you have a dry season, consider mulching onions with grass clippings or leaves. Be sure to keep the mulch away from bulbs to avoid disease and rot.

Onions are heavy feeders, so besides the initial feeding at planting time, they’ll benefit from fertilizer or a side dressing of manure when the bulbs begin to swell. Give onions adequate potassium or their necks will thicken and the bulbs won’t store well. As the onions start to mature, ease up on water and fertilizer to encourage dormancy.

One more tip: As the onion matures, pull the soil away from most of the bulb, so that only the roots and the lowest part of the bulb are in contact with the dirt. It will look as if the onion is sitting on top of the soil, as it should. This will aid in the drying process by keeping moist soil away from the papery skins. To ensure healthy bulbs, rotate the crop yearly.

If onion maggots are a problem in your area, don’t plant too early in the spring, and consider using row covers to discourage the egg-laying flies. When all is said and done, onions really are an easy addition to the garden, and they are virtually pest- and disease-free.

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posted in: onions

Comments (12)

VaneelaCharon writes: One of the great info for gardeners!!
Posted: 1:43 am on May 25th
Reechoclara writes: I love this info, it's truly valuable. thanks for sharing this!!!
Posted: 5:45 am on March 31st
APZ writes: Am delighted to have found this site. Am new into farming infact havent lasted even 3 mnths but have got the resiliance to give it a shot. Have started with onons and seams tricky,My onion starts shot up quickly and then flopped over and the foliage disintegrated. What did I do wrong or what should I do. Thenks for the article
Posted: 12:17 pm on October 10th
chuck50 writes: I have successfully grown onions from sets, with this drought not many producers in our area are planting for sets. I am planting seeds for the first time, both in the garden and in a flat to use as sets. I will see which works best here in central Texas! Thanks for the article

Posted: 4:16 pm on November 5th
AmandaMomRoss writes: My onion starts shot up quickly and then flopped over and the foliage disintegrated away. I read that the planting depth could have been to shallow or its possible I overwatered. Any thoughts? BTW: thanks for the article! This is my 4th year gardening and I still feel like I know next to nothing! Glad to have found a website with decent articles.
Posted: 10:25 am on April 2nd
Ruth writes: Good one, myseasons. I haven't exactly flunked Onions 101, but I've never gotten higher than a C-. Onions are one of those tricky crops for me (along with eggplant and melons). But I keep trying, and I hope you will, too. Even undersized onions have a lot of flavor.
Posted: 9:11 am on January 20th
myseasons writes: I have failed Onions 101 three times now. With this instruction sheet I will try one more time. Wish me luck.
Posted: 11:03 am on January 19th
gardengrower writes: Thanks for the great information. I'm going to link to your article on my gardening blog. Can't wait to try my onions from seed this year, last year even my sets didn't do well.
Posted: 10:56 am on January 19th
HunkieDorie23 writes: I am starting my onions from seed this year and appreciate the pic. I already started with individual seed trays but will try the trays next year. I planted my onions in rows of two last year and it worked great. Planning to do it again this year.
Posted: 9:52 am on March 30th
maybee writes: We live in Mississippi and last early summer planted onion seeds. Went out today to start cleaning the old beds and we have about 20 green onions growing. What a surprise!
Posted: 4:55 pm on March 16th
lettucegrow writes: The best article on growing onions yet. I have done ok. A little less than ok actually. Small bulbs but still tasty. I want big bulbs! I'll be using your tips this year. Thank you.
Posted: 2:47 am on October 18th
Lorithyme writes: This is a great article - so complete. Thanks
Posted: 12:47 pm on March 14th
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