How to Grow Onions, Shallots, and Leek from Seed

The following are a few tips gleaned from my own past blunders and successes in growing onions, shallots, leeks, and other alliums to help you get started with yours.

Onions & Shallots:

Depending on the type, onions are fairly flexible plants that will tolerate a certain amount of rule-breaking on your part. Bunching onions aka scallions tend to be tougher and can be direct sown outdoors in mid-Spring with some frost protection (a cold frame, bottle cloche, or cover).

Still, I usually sow a few indoors underneath lights along with my bulbing types so that I have a variety of plants available at slightly different times. Bulbing types require a longer growing season and must be started indoors early in cooler climates where the growing season can’t support them. The goal is to get seedlings into the ground sometime around or even before the last frost date. I try to start seeds around the beginning of Feb, but I find I can get away with as late as March in my region.

Don’t worry if you miss the early sowing period. Bunching onions are fast growers that can be harvested at any size. For that reason seeds can also be direct sown outdoors again just before the last frost date, and a final time in late summer in order to reap a fall crop.

If you’d rather forego seeds altogether, sets — small onions and shallots that are planted just like regular flowering bulbs — are another viable, albeit slightly more expensive option. I’ve had some luck with sets in the past, but will say that they tend to be more disease prone and are not as hardy and tough as seed-grown plants. There’s always a few duds in the bunch that don’t make it so it’s important to plant more than you hope to harvest.


Like bulbing onions, leeks are a long season crop that should be started indoors early when growing from seed. Like onions you can purchase seedlings later in the season so options abound should you miss the late-winter seed-starting window. Mature leeks are tough, hardy plants. I have managed to over-winter mine in the past, which results in beautiful, pom-pom-like flowers (and eventually seed) in their second summer.

Sowing Seeds:

  • I sow mine in trays, specifically recycled plastic clamshell packaging that I punch drainage holes into with a nail that I warm up over a tea light. Smaller pots with drainage holes (always with drainage holes!) are fine too when you’re doing a small amount of a particular variety.
  • Onion seedlings tend to grow a bit leggy indoors. It’s okay to give them a haircut with scissors now and again. Add the tender, young clippings to your meals!
Gayla Trail
Gayla is a writer, photographer, and former graphic designer with a background in the Fine Arts, cultural criticism, and ecology. She is the author, photographer, and designer of best-selling books on gardening, cooking, and preserving.

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19 thoughts on “How to Grow Onions, Shallots, and Leek from Seed

  1. I started the alliums about two weeks ago. I always have a hard time getting them to an equivalent transplant size of the ones at the nursery in the spring, so I’m trying an even earlier start this year.

    I also pick up sets in bulk at the country store. This seems to be the most cost effective option for sets at $1.69/lb IIRC. The selection is not the same as with seeds though. I’m growing ‘Parade’ green onions and ‘Ailsa Craig’ bulb onions along with ‘Hannibal’ ‘Giant Musselburgh’ leeks. (I’m also growing ‘American Flag’ leeks, received through a swap, though I discovered after sowing that they are apparently the same variety as ‘Hannibal’.)

    Have you ever experimented with growing your own sets? Dick Raymond mentions it in his book (the 1980s Joy of Gardening… I think you’ve mentioned it before) and I keep intending to try it, but the late-July early-August sowing of seeds never seems to quite mesh with my gardening and preserving schedule.

    I have had great success with overwintering leeks (even when temperatures dip below -20 for a week or more at a time) mostly ones that I missed harvesting in the fall!

    • I prefer to just grow from seed since I am starting them at a time when I don’t have too much going on. The late part of the season is too busy with preserving.

    • Hi Hazel, When overwintering your leeks, do you cover with dried leaves or straw, like one does garlic? Or do you just leave it uncovered through winter? Thanks.

  2. Yes, I have bunching Tokyo Green Onions that I sowed outside here in the SF Bay Area (already a few inches tall), and I sowed “American Flag” leeks on Feb. 2 indoors. It’s my first time trying leeks so it’ll be an experiment (as all of my seed starting usually is!). I also decided to set up a flourescent light after being inspired by your set up :)

  3. We love to grow all kinds of leeks,onions,shallots,walking onions,and egyption onions.
    Can we ever have enough of them?LOL! We eat them fresh,cooked,stirfried,in soups,on and everything we can get our minds to think up!
    I can’t wait to see their little grass like stems poking through the soil.We live in zone 9 and grow them all year long.

  4. I haven’t started mine yet, but thanks for the reminder! I have had limited luck with starting onions from seed, but I am always willing to give it another go. My winters are mild (US zone 7b), so perhaps I’ll sow them directly outdoors with the rest of my other winter-sowing project.

  5. Amy, I’m in zone 7a and I overwinter leeks, so give it a go for sure. I sowed leeks and green onions early last spring and had onions of varying size to pick all year. Anything I can direct sow is a plus, because sowing under lights is my least favorite gardening activity! And speaking of, thanks for the reminder, Gayla–I am already behind!

  6. I love the idea of heating the nail with a candle! When I tried to punch holes with a needle the plastic cracked, so I was cutting slits with an exacto knife. That didn’t work that well, so this year I will try the heated nail.
    The past couple years I’ve started tomato seeds in plastic solo cups only filled part way, and then when the seedlings are bigger I just add more soil so more roots can grow out of the stem. Probably not the best way, but it’s time efficient and reminds me how limited the space under my grow light is!

  7. I am curious to know if it would work to grow seedlings in a South facing window? I don’t have the money for lights but I have a shelf I can clear off in the laundry room and put in front of the window. Does anyone know if that would work well? Thanks!

  8. I see that you have cipollini onions in that collection of seed packages. I was wondering what sort of success you’ve had growing them in Toronto? I live in upstate NY (Mohawk Valley) and I’ve never tried to grow them as I always thought they were a short day onion and therefore I wouldn’t have much luck with them here. Is there something in particular you do to “trick” them into growing this far north?

  9. I just started my onions, although I’m only growing a few plants to see if I can actually get them to bulb up this year. Last year was my first ever vegetable garden, and my onions never got bigger than cocktail size! I was so disappointed. Any idea why this may have happened? I had a long-day variety. Thanks, and very much enjoy this site!

  10. When overwintering your leeks, do you cover with dried leaves or straw, like one does garlic? Or do you just leave it uncovered through winter? I’m in New England and have pulled and stored in damp peat and lost them all. Thanks for the reminder to get planting!

    • I have never done anything to mine. I’m guessing that mulching with peat may have been too moist… leeks generally prefer sandier or very well-draining soil.

  11. I started some evergreen bunching onion seeds in the window last week after reading this and getting inspired… but so far nothing has sprouted. I put some in the north window, and some in the south window, just to see which works better.

    I’m wondering if it’s too cold beside the windows… or maybe they take longer to sprout than I expected?

    • They will take longer if it is colder. I have some in a cooler spot as well and they haven’t germinated, while everything underneath lights have.

  12. Thanks! I will keep watering them, fingers crossed. I’m in Toronto too and I have to say the cold weather lately has kept it pretty frigid directly beside the windows. I can see why these onions don’t want to come up!

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