Planting Onions From Seed or Seedling

Why grow onions from seed or seedling rather than sets?


First of all, those mesh bags of onion sets always seemed so iffy to me. You get to choose from a limited variety, onions simply called yellow, white, red, or multiplier. No idea of what onion it actually is, where, or how it was grown. Likely not organically!

Secondly, onions grown from seed are more disease resistant, and grow bigger, better and faster, too. I found this out after breaking my wrist, one spring long ago, being unable to drive to the shops. Tossed some seeds straight into the garden beds and had the best crop of onions I had ever grown. I have never gone back to sets since! 


When you grow from seed, you have a great selection of varieties to choose from, all sorts of whites and reds and yellows.

A couple of my favourites are Tropeana Lunga and Lunga di Firenze, long torpedo shaped onions that are mild and sweet in flavour.

Walla Walla onions are always a big hit here on the west coast, too. Though they are not good storage onions, we can sow the seeds right into the garden bed several times a year, for fresh eating pretty much year round, including an over-winter sowing for new onions in spring.  


To grow your own seedlings, sow the seeds in flats or six packs in January or February, ideally with bottom heat. Onion seeds do not last long in storage, so is best to order new, fresh ones each year.

You should see the tops popping through in about a week's time. 

Once or twice during the growing phase, snip back the tops so they are 1 to 2 inches tall. This will help them to size up faster. 

Feed with liquid seaweed or kelp every couple of weeks. They will be ready to go into a cold frame in March or April, and then into the garden beds in late April or May.   

Seeds can also be sown directly into the garden beds in early spring, and will thrive just fine, growing bigger and better than the sets ever do. 


How to plant those seedlings? 


Onions are heavy feeders, so start with great soil, rich in nutrients. Make sure the soil is loose and well draining.

Make 2 inch deep furrows in rows that are 6 to 8 inches apart. This makes it easy to weed between the rows throughout the growing season. The Winged Weeder is fabulous for this purpose, best hoe ever.

I dust the furrows with a wee bit of blood and bone meal.

Cut the tops of each seedling down to about 1.5 inches tall 

Gently separate the seedlings.

Cut the top green growth to about 1.5 inches tall, to promote faster rooting in

Place in the furrows, 4 to 6 inches apart. I grow mine close together so that I get lots of good sized onions, but if you are growing larger onions, space them 6 inches apart.

Push the sides of the furrow together around each seedling, making sure not to bury it too deeply.
Covering just the red (or white) part of the onion, to where the green tops start.

Water in well.

 Two weeks later, they are making new tops

You will know that your onions are well rooted in when the tops start to grow up tall again. In about two weeks time, yous should see lots of lovely new growth.

Side dress with manure during the growing season to give them that much needed, extra boost of nutrients.

Onions do not compete well with weeds for nutrients, so run your hoe between the rows every week or two. 


Water once a week throughout the growing season, slowing down on watering as they get closer to the finished stage. 

If the soil is too high around your bulbs as they start to size up, brush away the soil so that just the bottom part of the bulb is in the soil. They should look like they do in the picture above. 

As the tops begin to fold over at the neck, they are nearing harvest time. Do not water at this time, let them sit dry until most all of the necks have bent over. 


Then lift the onions, place in a shaded area to cure, with great air flow. It will take 3 or 4 weeks to fully cure the bulbs.  

Onion with thick bull necks will not cure, so clean those up and use them up as you can your homemade pasta or pizza sauces. They can also be stored in the crisper for a few weeks, or chopped and frozen to be used at a later date.        


Clean off the tops, or make them into braids. 

Store in a dry, cool pantry to be used as needed. Not all onions are good storage onions, some varieties, like the Walla Walla, will only keep for a few months. 

Onions store well in baskets, apparently I bought this basket from Homsense for $12.99 ; )

 Beautiful Cippolini onions, cured and ready for the pantry. 

For your own better crop of onions, try growing from seed or seedling this year, too! 

Happy Growing! 

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