planting onion seeds

I have lots of experience with vegetable plants and vegetable gardening. Not bragging, just old. But I recognize that I’m not an expert on any of them, I’m very forgetful, and sometimes downright dumb. So like everyone else, I turn to the Internet.

One of the vegetables I’m very familiar with is the onion. Almost impossible to screw up, hardy, no real disease threats, and can be planted almost anywhere. But still, there’s more to know. I decided to start onion seeds indoors for the first time, and that’s what I did yesterday.

There are handy assets I can pull from; my brain, seed packet instructions, and the Internet. My brain doesn’t contain information on when to start these little seeds. The seed packet does. It says 10-12 weeks before last frost date. But there’s a wrench in the works. A different seed company says that if you want really big onions, start your seeds 14-16 weeks before frost-free date.

I do the math like a champ. 14 minus 10 equals 4. Dang, I’m good. 4 weeks equals 1 month. Told you. In my case that means now. And that’s an excuse to plant something in January. Baby!

I’m fairly obsessive about scouring the Internet when there are different answers to the same question, and that’s what I did. Forums, experts, seed companies. And as often happens, there aren’t agreed-upon standards for planting onions from seed. Plant them in flats, plant them individually in deep containers, plant them in huge bunches. Plant them in December, plant them in March, plant them in the garden.

Could be that they’re all good.

But I can use this confusion to try to end mine, by experimenting. Love those things. Experiments are like my own internal Internet. And they provide answers that I remember.

I’ll plant half my onion seeds now in January and half in a month. I’ll even try up-potting some of them into individual containers to see if it ultimately makes any difference in size.

Previous experience with other seedlings tells me that potting up to larger containers will make a difference. But I also have to consider my lighting real estate. What’s more important to me; tomatoes or onions? I’ll let you guess.

For this first batch of onion seedlings, I settled on 4-inch pots.

4" pots

They have more vertical space, which onions like, than flats or 6-packs. I filled them with the seed starting mix that I made yesterday and tamped each one down with the bottom of another pot. Then I stole my wife’s 1/8 teaspoon measuring spoon and filled it up (I figured about 50 onion seeds in each 1/8th tsp.).

50 seeds

Those were spread evenly over the soil in one pot and covered with about 1/4″ inch of the seed-starting mix, then pressed down again.


Finally, I spritzed the top of the soil to make sure the seeds got wet, and set the pots into water for 15 minutes to moisten everything without disturbing the seeds.

The final tally was four pots, or about 200 seeds, twice what I’ll need for the first part of the experiment. I’ll transplant some of them to nice, deep containers at some point, and leave the rest as is.

Then in about a month I’ll repeat the whole process, and hopefully determine whether planting early and/or up-potting are useful practices for onion seedlings.

My own answer. And one that I most likely will never have to look up again.


17 thoughts on “planting onion seeds

  1. I really like this plan! I have never had good luck planting onion seeds myself. Maybe I will give it another shot this way. Although, your math would be February in my part of the world. I did plant tomatoes very early one year, January I think. They got way too tall and gangly. I doubt onions would do this though. Good luck! Be sure to let us know.

    Liked by 1 person

  2. Great job, Dan. We start everything from seed each year, but being organic, we grow only the seeds that we harvest from the previous year. It also cuts down on the cost of buying each year. Keep up the great education for all of us to enjoy.

    Liked by 1 person

  3. In October, storage onion seed are broadcast in trays where they grow until being transplanted to the garden in February. Bunching onion seeds are broadcast to the garden in February. We’re zone 7b. Good luck with your plan, Dan!

    Liked by 1 person

  4. I’ve had no luck with onion seeds – I think the slugs eat the shoots – so I usually do sets. Maybe I’ll try seeds in pots this year to see if I can beat the slugs.
    Thanks for the inspiration.

    Liked by 1 person

  5. Do you grow any seedlings on using florescent lights, or strictly window growing? I’ve had some success in the past growing seedlings under regular 4-foot florescent shop lights, one cool and one warm bulb, each end propped on a paint can or stand about 6 inches over seedling trays, in a cool cellar. Once sprouted and growing, the coolness of the cellar seemed to lead to slower and more compact growth, giving me more time before planting out.

    Liked by 1 person

    • I do Daphne. All of my seedlings grow under shop lights with regular flourescent bulbs. I think you have a really nice situation with your cool cellar, because from what I’ve experienced thats where they do best, in a slightly cooler environment. If you’re so inclined, you might try those lights really close, like an inch or two, for 14 or 16 hours a day. Mine love that.


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