A Better Way To Start Onion Seeds Indoors

Last year, I started onion seeds indoors for the first time. They transplanted nicely, and I was able to harvest a few dozen small onion bulbs, but I really didn’t start them in the most efficient manner. So, I wanted to update you on a better way to go about starting onions indoors.

In my first tutorial, I showed you how I was starting my onion seeds in dixie cups. I guess I imagined the bulb growing in there, and I didn’t want to crowd each seedling.

But… ahem… it doesn’t exactly work like that. It takes MONTHS before a bulb forms! So, it’s actually quite alright to crowd them in the beginning.

With this knowledge tucked firmly under my belt, I was a little smarter this year, and broadcast planted my seeds in a tray. Onion seedlings are super tiny, so all you have to do is sprinkle them over the surface of some wet seed starting mix, cover them with a very fine layer of more seed starting mix, and water with just enough water to wet the top again.

To help the seeds germinate, I either use a salvaged deli tray with a lid, or I put my trays or cups in an open ziploc bag to create a little greenhouse and to help lock the moisture in. Then I place them on top of my fridge for a few days, checking every day for growth. Once the seedlings emerge, I put them under a shop light, about 2-3 inches from the bulbs.

Here’s my whole setup. I keep them in a tray with a little water for the seedlings to soak up. It’s very important the soil doesn’t dry out, and bottom watering is much better than trying to sprinkle them from above and disturbing the soil and roots. These are some red onions I started 8 days ago. (Thanks SJ!)

I’ll try to remember to direct sow some this year as well, and see how they do.

Do you start onions from seed? Have any pointers you can share?!

About Kendra 1103 Articles
A city girl learning to homestead on an acre of land in the country. Wife and homeschooling mother of four. Enjoying life, and everything that has to do with self sufficient living.


  1. Heres what I do—When I buy green onions from the store or from my garden-
    I chop a little above the roots and replant them. keep soil watered when dry, soon another green onion grows! Have fun in the garden.

  2. I start my onion seeds according to your second directions and have had very good luck with them. They do take quite awhile to form bulbs. The last couple of years I have purchased the onion sets from the hardware store, since I didn’t have my new seed starting set up done. This year I plan to start my own seeds again, and onions are one of the crops I want to start myself. You have so many more choices as to variety, rather than just red, yellow or white!

    Thanks for the reminder that I need to get moving on my set up 🙂

  3. Have you ever tried winter sowing? I am doing that with my onion seeds this year as space under lights is limited. I also want to try my hand this summer at making my own onion sets.

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