Is It Better To Grow Onions from Seeds or Sets?

Join organic farmer Jenna Rich as she attempts to answer the age-old question: is it better to start onions from seed or sets?

A close-up reveals onions, their bulbs nestled in rich brown soil. The bulbs, plump and firm, promise a bountiful harvest. Their vibrant green leaves stretch outward, catching the sunlight, while neighboring onions blur softly in the background.


Onions and garlic are the base of every meal in my home so I love having them around all year long. Growing vegetables in the home garden, especially these culinary staples, is economical, rewarding, and fun. 

Depending on your region and when your soil can be worked, direct seeding onions may not be a realistic option. So should you start them from seed or purchase sets? How onions are propagated doesn’t affect the final outcome as much as you might think. 

Let’s get into the different ways you can start onions and which way is better

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Cabernet Bulb Onions

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Cabernet Bulb Onion Seeds

Walla Walla Bulb Onions

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Walla Walla Bulb Onion Seeds

Tokyo Long White Bunching Onions

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Tokyo Long White Bunching/Scallion Onion Seeds

Short Answer

The best way to grow onions is a personal preference based on the following:

  • The amount of time you’d like to invest
  • What your space allows
  • How much money you’re willing to spend
  • The variety you select
  • Your growing zone 

While starting onions from seed may seem intimidating, they’re easy and beginner-friendly. Gardeners who don’t have an indoor setup may direct sow onions in their garden, but since onions take a long time to grow to full size, transplanting sets may be the best plan, especially for northern growers where direct sowing isn’t practical.

Let’s get into the nuances of starting onions from seed versus purchasing and transplanting sets.

Long Answer

How you get your onions in the ground is a personal preference. I’ll discuss different types of onions, briefly touch on how to start them from seed, and what to look for if you purchase sets from a gardening retailer. First, let’s discuss the different types of onions and how to choose the right one for you

Selecting Varieties

A close-up of onion bulb tips nestled in earthy brown soil; each tip promising the potential of future harvests. The bulbs, tinged with a hint of reddish hue, stand out amidst the soil. Verdant leaves reach upwards, seeking light in the dim surroundings.
Neglecting to consider the appropriate onion type can lead to problems.

Depending on what zone you grow in, different types of onions will perform better. 

  • Long-day onions need 14-16 hour days to bulb up and have a longer storage life. This type is best for northern growers above 35° latitude. ‘New York Early’, ‘Rossa di Milano’, and ‘Yankee’ are well-known long-day onions. 
  • Day-neutral or intermediate onions bulb up with at least 12-14 hour days, perfect for growers in zones 5 and 6 nationwide. ‘Walla Walla’, ‘Talon’, and ‘Cabernet’ are popular day-neutral varieties. These do well almost anywhere, though.
  • Short-day onions bulb up when days are 10-12 hours, and they are popular among southern, Southwestern, and Gulf Coast growers. These onions tend to be sweeter with a short shelf life and are best if used immediately. They are often overwintered for a spring harvest in warm regions and greenhouses. ‘Yellow Granex PRR’ is a delicious short-day onion.

Not considering the type of onion may result in tiny bulbs, premature bolting, or no bulb at all. 

Starting Onions From Seeds

A cluster of onion bulbs rests in rich, dark soil, their papery skins glinting in the sunlight. Each bulb is neatly spaced, promising healthy growth. Behind them, a bundle of onions awaits planting, nestled in a brown paper sack atop the earth.
Ensure airflow around onions to deter gnats and algae.

If you have ample indoor seed-starting space, starting crops from seed is a fun gardening activity that’s good for your mental health. Not only does soil contain beneficial microbes that may lead to lower levels of stress and anxiety, but studies show the act of gardening and being outside also has health benefits. 

Sow onion seeds in January or February, about 10-12 weeks before your last expected spring frost. Heat mats set to 65-70°F (18-21°C) will help them germinate quickly and evenly. Keep trays watered well, but don’t allow them to become soggy. Once you see germination in most of your cells, remove them from the heat mats if used and put them under artificial light or direct sunlight in a greenhouse. 

Pro tip: Fans are your friend. Creating airflow around your onions will prevent gnats from hanging around and algae from forming on the soil surface. Onions are in these cells for quite a while, so this is crucial. Also, sow more densely than recommended in your trays and separate them at transplant for even more onions.

As the onions grow, they’ll be thin and wispy. About four to five weeks before I plan to transplant my onions, I give them a haircut by taking clean, sharp shears and cutting them down to about ⅓ of the height. This forces energy into the root and bulks up the stalks of the onion as they regrow. 

Growing Onions From Sets

Various onion bulbs, each a different variety, sit snugly in assorted containers, ready for cultivation. Surrounding them are gardening tools, including a small rake, shovel, pruning shears, and pliers, suggesting meticulous care and preparation. The containers find their place amidst the brown, fertile soil, awaiting the gardener's touch.
Harden off onion sets before planting in the garden.

Maybe you don’t have an indoor seed-starting area, or perhaps you grow in zone 3 or 4, and it’s too late to start bulbing onions from seed. Enter onion sets. 

Onion sets can be found at local nurseries, or farm stands in the spring and summer, usually offered in four or six-packs. They’ll have been started indoors by seed 10-12 weeks before the area’s last frost, grown indoors for most of that time, and then hardened off before being offered for sale. When purchasing, consider how many onions you want to have on hand throughout the winter and buy accordingly. 

Allow the onion sets to settle into your garden’s environment by hardening them off for at least a few days before transplanting. Below, I’ve included a short list of things to consider before purchasing. 

To Transplant

A hand holds uprooted onion seedlings, their delicate leaves adorned with dark soil, and roots dangling beneath. The seedling, primed for planting, rests against the brown soil, ready to take root in the garden's nurturing embrace. In the blurred backdrop, black pots brim with onion seedlings, poised for their journey into the fertile earth.
Plant onions in rows with proper spacing.

When onions bulk back up after their haircut, and they’ve been properly hardened off, it’s time to get them in the ground. If you’re interplanting, plug them where you see fit in a hole 1 to 1 ½ inches deep. Squeeze them into place to secure good soil-to-root contact. Depending on the size, you may plant them in groups of two to four spaced at 12-15 inches or individually at 3-4 inches

If you are planting them in rows, create a furrow or dibble holes at your desired spacing and plug in your transplants. The soil should be well-draining, high in organic matter, and pH between 6.0 and 6.8. Onions should receive full sun. Since onions have shallow roots, consistent and deep watering is important. Soak them with drip irrigation one inch per week if no rainfall has occurred. 

Things to Consider When Purchasing From Retailers

A close-up reveals containers brimming with onion seedlings, their slender green leaves reaching upwards. Each delicate leaf exhibits a vibrant shade of green, contrasting beautifully against the red hue of the containers in which they're meticulously arranged.
Buy from reputable sources to avoid risks

Research the growing habits of any retailer you plan to purchase from. If you grow organically, only bring in transplants that have been grown the same way.

  • Ask what type of soil, fertilizer, and amendments they’re using
  • Examine plants for signs of disease and pests, including the root system 
  • Check that the leaves look healthy and the color they should be. No discoloration, dry soil, or drooping. Note cotyledons may have yellowed and that’s okay.
  • Ensure plants are not rootbound. It’s acceptable to gently pinch out the plants to inspect the bottoms!
  • Check the soil for visible pest eggs
  • Keep them indoors or in a greenhouse for one to two weeks before transplanting. Keep an eye on them before adding them to your plot. Return or discard them if you notice signs of disease or pests.

If you aren’t sure, steer clear. Only purchase from reputable sources. 

Consider Growing Green Onions

A close-up of green onions thriving in brown soil. The slender, elongated leaves of the green onions stand tall. In the blurred background, a multitude of green onions sway gently, a testament to nature's abundance.
Scallions are resistant to pests and diseases but mature much faster.

If bulbing onions aren’t your thing or you didn’t start them early enough in the season, try growing scallions! I squeeze these guys in between my full-size kale, head lettuce, and alongside my snap pea fence, and anywhere else I can; companion planting at its finest.

Their strong fragrance may deter rodents and pests. Like bulbing onions, scallions have very few pests and diseases, but they take much less time. Start them from seed and pop them in all season long to enjoy this delicious add-in, no matter your zone. 

Pro tip: Dehydrate chopped-up green onions and add them to soups, stews, and stir-fries all winter. 

Final Thoughts 

While you may think the how of deciding how to start your onions is the most important when in fact, it’s the what. No matter how onions are propagated, so long as they’re healthy and are planted in well-draining, fertile soil with lots of sunshine, they’ll succeed.

Select varieties that are known to perform well in your area and that you enjoy eating. Happy gardening!

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