how to save onion seeds

If Martha Stewart, Gordon Ramsay, Hester Blumenthal, and Anthony Bourdain all announce they’re going to show up at your house at the same time here’s what you need to do.  Fry some onions.  Maybe first you should make sure your phone is charged and Instagram updated, but then you should definitely fry some onions.

Nothing makes a kitchen smell like the cook knows what they’re doing like the smell of fried onions.  Baked cookies are fine for an open house, but if actual chef-like smells are what you’re trying to put out in the world, nothing tops a fried onion.  Lay a random weird ingredient like squid ink or dry ice on your counter and Martha, Gordon, Hester and Anthony will automatically give you chef status.  And not that stupid honorary status that Universities give to actors.

how to save onion seeds

Grow your own onions for cooking and they’ll be begging you to cook in their kitchens.  Save the seeds from your onions and grow them over and over year after year and tell them all about how you do it?  They’ll be asking you for cooking lessons.  ‘Cause you’ll seem JUST that smart, JUST that authoritative, JUST that committed to the world of food.


saving onion seeds

In the past I’ve shown you how to save tomato seeds.  I’ve also shown you how to save lettuce seeds.  Saving onion seeds is slightly different because onions are a biennial.

A quick explanation of seed saving:


There are 3 different types of plants:  annuals, biennials and perennials.

Annuals:  Plants that germinate, flower, produce seeds and fruit in a single season.  Then they die.

Examples of annuals in the vegetable garden:  Tomatoes, Squash, Cucumbers, Beans, Peas, Melons, Peppers, Potatoes.

Biennials:  Plants that produce fruit in a single season but don’t flower (which is where the seeds come from) until their second year.

Examples of biennials in the vegetable garden: Kale, Swiss Chard, Onions, Broccoli, Beets, Rutabaga. 

Perennials:  Plants that go through the entire cycle of producing and flowering every year, over and over for many seasons.

Examples of perennials in the vegetable garden:  Raspberries, Strawberries, Rhubarb, Asparagus.

A simple way to identify a plant as either annual or biennial is if the vegetable contains seeds right in the actual vegetable it’s an annual.  If there is no seed in the vegetable then it’s a biennial.

Also if every year you go outside and there’s that stupid plant again even though you wish you could kill it, … then it’s a perennial.

This isn’t true all the time and there are exceptions but it’s a good rule of thumb to go by.


saving biennial onion seeds

So how do you save the seeds from a biennial?  What zone you live in will dictate how you do it.  If you live in a  zone where the cold doesn’t kill your plants, you simply leave a few of your chosen biennials in the ground.  In the spring they’ll start to grow again, sending up a shoot with a flower on top.

That was the case with these green (spring) onions I left in the ground last year.

Other plants like swiss chard or beets may get killed by the cold so saving those seeds is a bit different.  I’ll get into how to save beet and carrot seeds in another post.

Onions will survive the winter in my zone of 6b.  So getting them to flower is just a matter of leaving them in the ground and remembering not to pull them in up the spring when you wonder what the hell this weird onion is doing in the middle of your garden.

Anywhere from May to July (depending on the variety and your gardening zone) the onion will send up a shoot with a big pretty flower on the top.  Just let it keep growing.  Eventually tiny seeds will form. When the seeds have formed cut the flower stalk and allow the flower to dry.  Once it does you can just shake the seeds out.

If you want to plant immediately you can also hand pick the seeds out of each tiny, individual flower.

The reason I cut the stalk off and let it dry on my porch is so I don’t lose all of the seeds.  If it dries in the garden all the seeds will drop into the soil.

A quick guide to saving onion seeds

I harvested these seeds in June and will be bringing them up to the garden with me today so I have a new supply of green onions.  And yes, I’ll be leaving a couple of them in the ground so next year I can harvest more seeds and do the same thing over and over again year after year.  I’m a perennial gardener.

One final tip before I go … don’t let Martha and Gordon sit beside each other at dinner.  Just trust me on that one.


  1. karin sorensen says:

    ah, that reminds me, one of my green things bolted and has a bunch of seed pots. i don’t know what to do with them. i wonder if i can apply your method to at least get some seeds out of the darn thing.

    i think it’s a radish… thus proving to the world that my gardening skills are less than stellar this year. i had a great spreadsheet at the beginning of the season, everything was labeled, in order and every little leave emerging was documented.

    did not quite account for the massive amount of greenery that was soon to take over the house, strangle the cats and give the husband the leavy old eyeball. so in a frenzy i threw everything outside and kinda forgot to label half the shite i grew…. yeah, i didn’t plan this all the way through. anywho, do you think your method for collecting seeds would work for the supposed radish?

    and thank you eternally for breaking down the three major plant groups, i finally got it. it’s stupid simple, but for some reason i couldn’t wrap my head around it before.


  2. Monica says:

    Question about the rhubarb: How much do I need to leave? As in, if I wanted to cut and freeze a large bag of the rhubarb plant I planted this year, could I cut off 90% of the stems? Or should I be leaving most of them in the ground?

    • Karen says:

      Hi Monica! I don’t think I’ve ever picked my rhubarb plant completely clean, but I’ve come pretty close. I’ll just leave a couple of the smaller newly sprouting leaves.
      It’ll continue to produce if it’s healthy until the fall. ~ karen!

  3. lisa says:

    Wait a sec…Kale comes back?
    Do I just leave it alone, or cut it back in the fall?

    • Karen says:

      Just leave it alone. But it depends on kale. Some are hardier than others. You can try to protect it with fleece etc. ~ karen!

  4. MartiJ says:

    Fennel. Because… I needa know how to grow my own on that one, please?
    I have two fennel plants growing bulbs. No idea where it goes from there.

    • Karen says:

      I know nothing about saving Florence fennel seeds! (those are the one with bulbs as opposed to just fronds). It’s a biennial but I’m not sure how hardy it is and whether or not it would survive a winter protected outside or if you’d need to pull it and replant it in the spring like beets.~ karen!

  5. Nancy Blue Moon says:

    OK…that’s cool!…I’m sleepy 😪 now…nite…….

  6. Sandra D says:

    Her mom would take them shopping, I mean!!

  7. Sandra D says:

    I forgot to tell you a story – related to “smelling like a chef”.

    My friend grew up on a farm in Alberta. Her dad would be out in the fields working, and she’d take the kids into town on a shopping trip. Well, it might be late when they got home, so the first thing she did was fry up some onions.

    Hubby would come home from the fields, smell the onions frying and figure supper was on its way. He’d sit in his favourite chair and have a nap. By the time he woke up (or was woke up), supper was on the table.

    I’ve had the opportunity to try it and it works fine (no visitors needed). Smellalicious.

  8. Sandra D says:

    I have what are called “jumping onions”?? I get them coming up every year. They’re best at green onion size. They never get big enough to be called onions.

    I love chives – they come up everywhere; I don’t bother buying green onions at the store in the summer, even if they’re 50 cents a bunch (remember when they were 25 cents)?

    I’ve also had tomatoes come up in the garden the next year. Too bad I’m in Calgary – no way they have enough time to grow.

  9. Sabina Missana says:

    So I planted green onion seeds in one of my containers two months ago and I’ve got green dental floss, wtf? Should I have planted sooner? I’m not too far from you so you know the kind of weather we’ve been having this year.

    • Erin says:

      Hi Sabina –
      If I am growing onions from seed, I have to start them in Feb. or March inside to get a decent sized onion (Bruce Peninsula.) They grow realllllly slowly. And the weather this year definitely isn’t helping.

  10. Linda in Illinois says:

    always great information. I planted seed of onion three years ago, from a major brand seed packet and this was the only one that came up, the plant comes in every year, but I have never gotten a seed head on it. Maybe it is sterile ? Or perhaps needs two to make a head? Advise?

  11. BaconBleuCheez says:

    Annuals: Plants that I kill in a single year.

    Biennials: Plants that would live two years, if I didn’t kill them in their first year.

    Perennials: Theoretical plants that “could” live multiple years. In the real world, aka my garden, they do not exist. I can kill anything in a single year.

  12. Cheryl Rosbak says:

    A timely post – my onion just bloomed last week and I was wondering what to do with it.

  13. Kelly says:

    By every time I cook onions I walk around smelling like BO and I don’t realize it until the next day when I can still smell the clothes I was wearing!

    What’s the trick for not offending other’s nostrils after you cook the onions then leave the house? (Besides not leaving the house?)

  14. Mary W says:

    How do I know when the onion seeds are ‘ripe’? If I pick them too soon, they will not be ready – if I wait, they will drop in the garden. When is the perfect time to pick the seed heads? I don’t grow them, was just curious. I re-seed my annual flowers when I can but sometimes I pick the flowers that are not ripe and the seeds not ready – waste of a good flower.

    • Karen says:

      Once you can see the seeds in the flower head. You’ll see they’re black. Then you know they’re good to go. ~ karen!

    • Diane says:

      As long as you pay reasonable attention to your green onions, you don’t have to worry too much about losing too many seeds. Like Karen said, when you see the black seeds is when it’s ready. If it’s been black for a bit, you’ll still get plenty of seeds out of it. It seems to take weeks for mine to drop nearly all of their seeds, but it’s not too windy in my area so that plays into how many seeds drop. Just don’t worry about being a few days late, it’ll be fine.

      PS. Karen… I don’t like the Choose File button. I never pay attention and I always click it instead of Post Comment. I don’t care if you keep it or change it. I just wanted to whine.

  15. Dale R Lacina says:

    Gordon Ramsay has ruined me for going to fancy restaurants to eat. If I am not hearing obscenities coming from the kitchen, I don’t think I am getting good food. LOL

  16. Kathleen Aberley says:

    Gordon Ramsay at MY dinner table? Not a chance! (I was going to say, not a F*#k, but thought I should not lower myself to his level) :)

    PS I have to thank you for introducing me to The Tragically Hip. I’m sure there are not many South Africans who know their music. Besides Bobcaygeon, I am loving Cordelia. Actually, just loving their music. Thank you again.

  17. I know you must have put something in your posts about getting broccoli to make heads bigger than 1 cm, but I can’t find one. My broccoli is nearly three feet tall (slight exaggeration, but not much) and I get little yellow flowers and miniscule little heads widely spaced on stalks. It doesn’t look like any broccoli I have ever bought in a store. I grew the broccoli from small plants I bought at a garden centre.

    Any suggestions?

    • Ev Gilmar says:

      There are many different varieties of Broccoli (as there are with other plants) and your broccoli sounds like one of them – not your usual de Chico variety.

    • Karen says:

      Hey Madeleine. Yeah, things with heads seem to be more difficult to grow successfully. Broccoli, cauliflower … It could be your variety. I grow Green Goliath broccoli and it *usually* gets a decent sized head, although sometimes not. Also make sure you’re fertilizing. Ultimately it could just be the weather. Or vegetable gardening demons. ~ karen!

    • Jenifer says:

      I’m with you on the broccoli. I tend to leave them too long and they go to flower. I’ve found that if I cut the crowns BEFORE they go to flower, the world is a better place. Once they go to flower there is nothing to be done except to open a(nother) bottle of wine and eat leftovers!

      Last year I had over 60 (yes, sixty) broccoli plants that I grew from SEED (thank you, thank you very much) and I head. NOT ONE! Best guess is that some bastard bug (snails?) ate them as they started. bastards. Still makes me want to cry.

      Good luck to you and your broccoli adventures and beware of the evil forces (or bugs, whatever…)

      • Madeleine says:

        You grew 60 plants?! I’m humbled.

        As for not getting any heads, this means war. Next year I’m going to do my research and do WHATEVER IT TAKES to get at least one broccoli head. We will not be defeated by broccoli!

  18. Dale R Lacina says:

    One biennial you will not see in my garden is Kale. Just won’t happen. See no reason to sacrifice ANY space in my garden for Kale. Sorry Kale fans. No interest in Kale. No way…no how.

  19. Flash says:

    Ok. Got to give something new a try.

Leave a Reply

Your email address will not be published. Required fields are marked *

  • About Karen