Planting Onions From Seed


See also How to Start Seedlings Indoors

Growing Onions from Seeds or Sets?

I’ve grown most of my storage onions from seeds rather than ‘sets’ for years now. Originally I started sowing onion seed because I wanted to try some new varieties. When you purchase sets your choices are limited. There are yellow, red, and maybe white storage onions available in net bags widely available at hardware stores, nurseries, and the big box stores every spring.


Way back in the day (I’m dating myself a little bit!) I could get those bags of onion sets for about 2/$1. This year (2013) they cost $1.69 a bag. Not a bad deal if you are short on time, but pricier than starting from seed. You also get quite a few that are shriveled or moldy, so the 100 sets you start with is reduced a bit. The most recent packet of heirloom onion seed I bought came from Seed Saver’s Exchange in Iowa and ran me about $2.49. I just planted the last of those seeds after 3 years. They are ‘Yellow of Parma,’ an Italian variety that touts excellent storage qualities…to which I can attest. We still have a handful of sound specimens in my ‘root cellar’ and they definitely outlived the onions grown from sets.

Onions in my garden last year…right next to the strawberry bed.

Besides the fact that it is less expensive to grow your onions from seed and you have a greater choice in varieties, I have one more reason for choosing to plant onions from seed. I’ve found that onions from seed tend to ‘bulb up’ better than the onion sets purchased in the little net bags. Many of the sets produced very small bulbs or else they never formed a bulb at all. Instead, the bottom of the onion grew to about the same width as its ‘neck.’ Those puppies don’t store well and should be used up soon after harvest. The other problem I’ve found with onion sets is the tendency to go to seed in their first year.

A casualty…onion sets often have quite a few moldy or shriveled specimens in each bag.

Onions Are Biennials

If you are interested in saving seed from your onions to grow future crops, you will need to leave them in the ground over the winter to produce seed the second year. A good layer of mulch will protect them from freezing and rotting. The reason onions grown from sets sometimes flower and set seed their first year is due to the process used to raise them for market. Onion seeds are planted out, allowed to grow to the size of a small bulb, then they’re harvested, dried, and shipped to garden centers. We plant them out in our garden and give them the water they need to continue their life cycle. Sometimes this treatment tricks the onions into ‘thinking’ that they have lived out their first year, went dormant, and now they should produce seed for the next generation. I’ve never had onions from seed go to flower their first year, so I tend to get a better yield from them than I do from the sets.

Onion sets, ready to plant.

Planting My Onions This Year

Now don’t get me wrong…I still plant onion sets sometimes. I mean, really, how do you walk through the garden aisle at the hardware store without having a bag (or three) of those cute little onion sets jump into your cart? It’s nearly impossible for me to resist the temptation, even though I grow more onions than we usually can eat. So I already spied the onion and potato sets last weekend, but my willpower remained intact. However, it does tend to crumble after one or two trips to the hardware store. And now that I’m writing about the pros of planting onions from seed, I feel it’s my responsibility to plant both sets and seeds this spring to show you the differences this fall. (Sorry folks, that didn’t happen!)

The heat mat will help my seeds sprout quickly.

For Complete Seed Starting Instructions…

Please visit the chapter I wrote for Farm to Table Through the Year. My chapter is May and I give step by step instructions for starting seedlings inside and hardening them off.

But, I digress. Yesterday I planted seeds for the following: ‘Lancelot’ leeks, bunching onions, ‘Yellow of Parma’ storage onions, and ‘Copra’ storage onions. They have been watered in, labeled, and tucked into recycled ‘mini-greenhouses’ on a seed starting mat in the basement. Now I must wait for them to sprout and grow a bit before I transplant them into larger pots and move them to the greenhouse. I’ll harden them off and plant them out in rows when our temps remain above freezing for a bit.

Onions are biennials, meaning they flower and produce seed in their second year.

Do you plant onions from sets or seed? Which do you like better?



    • Lisa Lynn
  1. Carey
  2. littlemountainhaven
      • Deb
      • littlemountainhaven

Add Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.