Skip to Content

Growing Onions from Sets vs Seeds: Which is better?

Gardener holding up a bushel of picked onions with greens and long roots

Onions are one of the easiest vegetables to grow. They can grow in small pots indoors, or in the garden, they only require watering once a week, and they typically produce a pretty high yield without too much effort. They are a greater starter crop for gardening novices. Onions can be grown from sets or seeds, but which is better? Both have their own benefits and downfalls. Keep reading to find out if you should start your onion garden from sets or seeds. 

How do you care for onions?

Though onions are pretty low maintenance, they still have a specific set of conditions that will make them grow their best, and produce the highest yield. There is no one-size-fits-all when it comes to gardening, but luckily onions aren’t too complicated. Growing onions from sets or seeds will require similar care instructions with just a few tweaks. 

Stargazer Perennials Mixed Red, White and Yellow Onion Sets 8 oz | Organic Non-GMO Bulbs - Easy to Grow Onion Assortment…

When should you plant onions?

Both onion sets and seeds can be planted in the Spring. Onion sets can be planted as soon as the soil can be easily worked after the last freeze. Onion seeds should be grown indoors for 6 weeks[1] before being planted into the garden. Onions can also be planted in the fall but will lay dormant over the winter. Fall planted onions should be planted 4-6 weeks before cool weather, as they will need warm soil to properly root. Through the cold months, onions will lay dormant and will sprout in the Spring. 

How much sunlight do onions need?

Onions require full sun, so when planting, pick a spot that will get plenty of sun for the majority of the day. The bulbs will grow larger the more sun they can get, so be sure they are not being blocked by other plants. If you are growing your onions indoors in a pot, be sure to place them in a sunny spot like a window sill or another area that gets direct sun for several hours out of the day. 

What kind of soil do onions need?

Onions grow best in soil that has a neutral pH. When planting in the garden be sure the soil is free of any rocks or large debris. Onions prefer loose and well-draining soil. Well-draining soil will make sure your onion bulbs are being watered to the root, but not being drowned out by excess water. Soil that is too tightly packed will inhibit the growth of onion bulbs. 

How much water do onions need?

Onions need “about 1 inch of water per square foot per week”[1]. You should water more often during hotter weather to keep onion plants from bolting. If you live in a warm climate that doesn’t get much humidity you can lay mulch on top of your onion plants to keep the soil moist. 

What kind of fertilizer do onions need? 

Onions love compost and fertilizer as it gives the soil much-needed nitrogen and phosphorous. “Phosphorous is critical to bulb formation, so select a balanced fertilizer or one that has more phosphorous than nitrogen”[3] when planting your onions. 

Stargazer Perennials Mixed Red, White and Yellow Onion Sets 8 oz | Organic Non-GMO Bulbs - Easy to Grow Onion Assortment…

What are onion sets?

Onion sets are little immature onions that can be planted directly into the soil. They mature completely over a period of 14 weeks[1]. Onion sets look like small onion bulbs and can be purchased at most grocery stores. They should still be planted in the Spring or Fall depending on when you want to harvest and require full sun just like onion seeds. Onion sets can grow in loose prepared soil in the garden, or in gardening pots indoors or outdoors. Onion sets should be planted 2-6 inches apart[1] allowing them enough room to grow full bulbs and should be planted no further than an inch into the soil. 

Benefits of growing onions from seeds

One of the main benefits of growing onions from seeds is that they are much more affordable. A pack of onion seeds will set you back just a few dollars, or sometimes even less. Onion sets are more expensive and are sold in quantities less than the number of seeds. Onion seeds can also be planted any time of year, and are less likely to flower or bolt as they will put all of their energy into growing large healthy onion bulbs. Additionally, onions grown from seed can be stored much better over the winter[2] whereas onions grown from sets do not store well and should be used immediately after harvesting. 

Disadvantages of growing onions from seeds

Growing any plant from seeds can be more intimidating as seedlings are very vulnerable and require more delicate care. They also take much longer to grow which can be seen as a major disadvantage. Seeds also typically require replanting. Seedlings are usually grown in a seedling tray until firmly rooted and then transferred into the ground. The transferring process can sometimes shock the seedlings if the ground is not properly prepared, or if they are planted during inconsistent weather.

Yellow Onion Sets | 40 Onion Bulbs Onion .for Planting

Benefits of growing onions from sets

Onion sets are great for novice gardeners. The biggest advantage of growing onions from sets is that they are super easy to plant. They can be planted directly into the garden in prepared soil, or in a pot to start. They can grow to maturity in a pot without having to be transplanted, but you will have less space to grow in a pot. Another benefit for a novice or impatient gardeners is that you see practically instant growth and transformation. Onion sets will also grow faster because you can cut down on the time that would be spent growing onions from seedlings to the size they are when they are planted as sets. 

Disadvantages of growing onions from sets

Though sets may have a lot more benefits for you if you are a novice gardener, they do come with a few downsides. For one, they are much more expensive than onion seeds. You can get a hundred onion seeds for just a few dollars whereas sets are much more costly for much fewer onions. Onion sets when they mature also do not store well in the winter[2] and typically need to be used right away after harvesting. Additionally, because onion sets don’t have to focus as much energy on growing their early bulbs, they pose a higher risk of flowering and bolting. Another downside is because onion sets are purchased already partially grown, you likely won’t know the conditions they were initially grown in. Onion sets may have been grown with harsh chemicals or pesticides that you are unaware of. 

30 Walla Walla Onion Plants- Sweet,Delicious for fresh slices on sandwiches

Which is better?

Growing onions from sets or seeds both come with advantages and disadvantages. Whether you choose to grow onions from sets or seeds will depend on your climate, how much daylight your home gets, your experience level, and personal preference. If you are growing onions in the ground rather than in pots or raised garden beds, you will also benefit from knowing which types of onions grow in your specific climate naturally. 

So, which is better? Well, the answer is, it’s up to you! For novice or impatient gardeners, you may prefer growing onions from sets. For gardeners who want more variety, or want to control the growing process entirely of their onions, you should grow from seeds. Growing onions from seeds will likely result in larger onions that you can story all winter, but growing onions from seeds have a quicker payoff, and you can enjoy them a bit sooner. Both will require similar care, like plenty of sun, and adequate water. No matter which you choose, onions are relatively low maintenance, with seeds being slightly more high maintenance, and sets a little more simple. Regardless, onions are a great addition to your garden and will add some extra flavor to your dishes. 


Article Sources:

  1. Almanac. “Onions
  2. Do Not Disturb Gardening. “Should I Plant Onion Seeds or Onion Sets in My Garden?
  3. SFGATE. “What Soil Amendments Do Onions Like?

Our Most Popular Herb-Growing Guides