
How do you grow your onions? I bet you buy small bulbs (A.K.A, “sets”) and then you plant them, don’t you? Well, let me tempt you with another method: have you ever thought about growing them directly from seed? Yes, like many other plants and vegetables you can literally sow your Allium cepa varieties and watch them grow into seedlings, and then get bigger and bigger bulbs till they are ready to harvest!
“Ok, that looks like fun,” you may say, “but why should I do it?” If you follow me, I’ll show you quite a few good reasons to grow onions from seeds and I will also show you how to do it right and get a bountiful harvest in due time – for very little money!
Curious?
Advantages of Starting Onions from Seed Over Sets
Grow Onions from Seeds and You Will Save Money!
Money talks, and onion seeds cost so much less than sets! You can literally fill a big vegetable bed with as little as 1.5 to 2 dollars, and have more to spare as well! Ok, it does depend on the variety, but their price is really ridiculous for the harvest you get.
True, you won’t need to take out a loan if you choose to grow them from sets either, but every penny counts, and, especially if you want to grow lots of them, seeds can save you quite a few bucks over time. Actually…
You Can Grow Onions from Your Own Seeds
Like with peppers and tomatoes, you can simply save the seeds of your own onions at the end of the season, and then sow them. In this case the cost is literally zero cents! To do it, pick one or more of the biggest onions, and let them flower and then go to seed. Once the stalk has dried up, they are ready.

But it is not all about money… You may have a variety that you want to grow next year, and, apart from the most common ones, you may not find the sets again next year…
One drawback is that you may lose some of the seeds, not all of them may germinate – but is this really a problem when you have so many and for free?
There’s another tiny issue too; seeds can be more variable in quality than sets. However, to be honest, onions are quite stable (they are not like fruit trees – you never know what you get), and you can turn this to your advantage… How? I have already told you… Let the biggest onions go to seed, next year, it is called human selection, and it’s how vegetables and fruits have become better and better and bigger and bigger over time (before hybridization and then GMOs).
This way, you can even develop “your own variety” over time…
There Are Many More Onion Seed Varieties Than Sets

One of the great advantages of sowing onions instead of buying small bulbs is that you will literally find a huge range of varieties, all of them if you look carefully. And nowadays, with online outlets, it’s even easier to find them.
When nurseries grow sets, they only pick a small range of the most common onion varieties, for many reasons, first of all, they have a limited space to grow them. But it’s also due to the market… Why should they grow small bulbs of lesser known types when they know they won’t sell them? And why should they take risks?
In fact, this “habit” of growing onions from small bulbs is limiting the range of varieties we find, the biodiversity… And this is an added, if you want ethical, or ecological advantage of growing them from seed.
Onion Seeds Preserve Better than Sets

And here is another advantage: onions preserve quite well overall, also big ones, but… Little bulbs can catch diseases if they are not kept in the right conditions, and they often travel a lot from the nursery to the retailer. What’s more, many outlets (big stores especially) don’t keep them in the best place (they are usually by the shop window, noticed?)
On the other hand, onion seeds will last in perfect health for at least one year, and up to three. Their germination rate will drop past the first year, but still. Once they have been put in the packet, they will have perfect conditions till you sow them!
Onions Grown from Seeds Are Stronger Than Those Grown from Sets

Interesting, isn’t it? If you grow onions from seed, they will be healthier and stronger! This is for a few reasons, including the fact that you will transplant them straight away… You don’t need to dry them up and, above all, they won’t need to travel and adapt to a new place.
Plants are not that dissimilar from us; they grow accustomed to a climate, and they also develop their immune system against local diseases if they are born and grow in one place.
You Can Hybridize Onion Seeds and Create New Varieties
And if you are a playful and innovative gardener, you can hybridize two varieties you have grown and see if you come up with a new one – who knows, it may make your fortune! Ok, this is not an easy job, and we won’t see it here, but in case…
Growing Onions from Seeds Is Good for Self-Sufficiency and…
If you need to buy little bulbs every year, you depend on nurseries and outlets – so you are not self-sufficient. But if you reproduce them by seed… And if you are a homesteader, I guess this point has clenched it for you, and, yes…
An added bonus… Not all sets (nor seeds) are organic, and when they are, they cost more. But what does “organic mean”? On the label, that they have been grown with no chemicals for 3 years. So, whichever onion seed you choose, after three years of sowing, reproducing, harvesting etc., they will be fully organic (and you will be sure about it)!
Finally… It’s a Lot of Fun!
We love gardening for many reasons, to have food or flowers, to save money etc… But deep inside we all do it for fun! And growing a plant from seed is a totally different and more fulfilling experience than transplanting a seedling or planting an onion set!
Are There Any Disadvantages in Growing Onions from Seed?
Yes, and I am always honest. There are some disadvantages…
And now that I hope I have convinced you to grow onions from seed and not sets, you will be asking me, “How can I do it, then?” Let me tell you…
Growing Onions from Seed Step 1 – Choosing a Good Variety for You (and Your Climate)

White, gold and red, shallots, sweet and small and big… Ok, that’s about color and flavor, then you can pick an heirloom variety or a new cultivar, but there is more. Choose a type of onion that grows well in your climate. And how? There are three categories; so, check it out before you buy seeds:
Next…
Growing Onions from Seed Step 2 – Time the Sowing

In any case, you will be sowing onion seeds in winter! Because you want them to move outdoors as saplings in early spring. This will give you the best growing conditions and all the season to fatten them up, aiming to harvest them by late summer.
But I want to help you to time it perfectly!
As we said, it takes 90 to 150 days to harvest the onions you have grown from seed. While you could pick them all year round in mild regions, you want to time your sowing well, so the crops are ready when you want them.
What’s more, you can start them indoors or outdoors, so, you need a breakup of the main phases.
So, they need 9 to 14 weeks indoors, depending on the growing conditions and varieties. Because you want to make the best of their outdoor season, calculate these weeks before soil temperature reaches at least 50°F (10°C) as a night minimum outdoors.
It will be spring, but when exactly depends on your climate region. Better be safe than sorry, if you ask me.
Growing Onions from Seed Step 3 – Sowing!

This is the moment you have been waiting for… Finally, it is time to sow your onion seeds! Let’s do it then…
Keep checking on them, and water them from below when the top soil is dry. Nothing else to do for the next 9 to 14 weeks… Till your onion seedlings are ready to go outdoors!
Growing Onions from Seed Step 4 – Acclimatize the Seedlings

When the seedlings are 3 to 5 inches tall (7.5 to 12.5 cm), it’s time to get them accustomed to the outdoor climate, as they will soon be living there. If you have timed it well, this will happen in early spring…
You don’t want your tender seedlings to be stressed when they move outdoors to your vegetable garden. That will delay their growth and it makes it difficult for them to establish themselves.
Therefore, when they approach that height, put them outside for 2 hours, in a sheltered spot in part shade, at the peak of the day’s temperature.
Then, step by step, increase the time they spend outdoors, adding one or 2 hours every day, till you leave them out from morning to sunset. Now they are ready to be transplanted.
Growing Onions from Seed Step 5 – Transplant the Seedlings

By now, your seedlings should be 4 to 6 inches tall (10 to 15 cm), and outdoor soil temperatures should be stable above 50°F (10°C), and it is finally time to transplant them!
Then wait till harvest time!
Growing Onions from Seeds to Harvest
So, growing onions from seed to harvest is not much different than doing it with other vegetables. But it’s certainly better for so many reasons, cheaper, more sustainable, you have healthier bulbs, a much bigger choice… But I go back to the main reason, at least for me – it is much more satisfactory and lots of fun!

Written By
Amber Noyes
Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.