When I first started gardening, I didn’t know whether I should plant onions from seeds or sets. Both methods have pros and cons, as I have learned from my experience and research on growing onions, but here is my recommendation, as well as other information I have collected.
So, should you plant onion seeds or onion sets in your garden? In most scenarios, it is better to plant onions from seeds because it will give you the best chance for large onions that you can enjoy immediately after harvest or store successfully for the winter.
Difference Between Onion Seeds and Onion Sets
There are some key differences between planting onions from seeds versus sets. First, we need to make sure we understand the meaning of an onion set.
Onion sets are plants that were started from seeds – normally in the middle of summer to fall. The onion grows to the size of a small bulb and is then pulled out of the ground. It is dried and stored in a dormant state and can then be used to plant as a “set” the next spring.
What are some advantages and disadvantages of using onion seeds and onion sets?
- Very easy to plant
- Can be planted in spring when the ground is thawed
- More instant gratification as a gardener when you see new growth happening quickly
- Much more expensive to buy
- Do not store well over winter, must be used right away after picking
- High risk of flowering and producing seed instead of growing a large onion bulb
- Less likely to know what condition the onion sets were grown in – organic, chemicals, pesticides, etc?
- Seeds are much cheaper to buy
- Seeds can be planted just about any time because they don’t mind the cold
- No risk of flowering, will put all energy into growing large onion bulbs
- Can store the onions over winter if cured properly
- Will be happier and healthier plants because their growth won’t be stopped like sets
- Peace of mind that you have grown your onions in a 100% organic environment
- May be more intimidating to plant seeds
- Takes longer to see growth
I think you can see why I recommend growing onions from seeds instead of sets, right?!
We are all about frugal living and growing organically in our home. You will easily spend $5 or more on an 80 count bag of onion sets. However, I buy my onion seeds from MIgardener and get 250 seeds for $1!! Wow, what a difference! I also like knowing that my onions grew in my own organic conditions from seed to onion and not partially grown somewhere else where I have no idea what kind of soil was used for them to grow.
Another big reason why we grow onions is so we can cook with them and not buy them from the store. Since onions grown from sets don’t store well, we’d have to use all the onions right away, which isn’t possible. Growing onions from seeds allows us to grow a large amount of onions, dry and cure them properly after being harvested, and store them for use all winter long!
Just knowing that starting onions from seeds is the best path to success isn’t quite enough. It’s also very important to pick out the right type of onion to grow for your area.
What Type and Variety of Onion Seed Should I Plant?
There are different types of onions that you can grow based on your location and hardiness zone.
- Form bulbs with 10 to 12 hours of daylight
- Generally for hardiness zones 7 or warmer, so if you live in the southern US, these are the onions you should be growing!
- Can grow in the north but won’t form large bulbs
- Form bulbs with 12 to 14 hours of daylight
- If you live in the middle of the US, or zones 5 to 6, you could grow day-neutral onions successfully
- Can really grow anywhere except for the far south
- Form bulbs with 14 to 16 hours of daylight
- Ideal for northern gardeners zones 6 or colder
- Will not form bulbs if grown in the southern US
The variety of onion is also important and all depends on your personal preferences and goals with how you’d like to use your onions. There are so many different kinds of onions that I won’t try to list them all out here. However, onions are grouped into some common categories. Here are some common varieties and generally how they are best used.
Yellow onions are probably the most common and versatile type of onion. It’s probably the type of onion you have most commonly bought at the grocery store! They have the best balance of sweet and strong flavors and can be used in almost any dish. Yellow onions are usually about medium in size. One big advantage to yellow onions (other than their versatility) is that they last the longest in storage.
White onions have a stronger and more pungent flavor than yellow onions. Certain varieties can also be larger in size. You can cook white onions but they are more commonly used fresh on sandwiches, in salads, and in salsas. These onions do not store as well as yellow onions.
Red onions can be the most astringent type of onion depending on personal taste. They are similar to white onions in that they are used most often in raw form. Red onion is probably the most common type of salad onion. Red onions do not store as well as yellow onions.
I enjoy experimenting with many different types of onions. We grew red onions this year for the first time and they turned out well! Check out a picture of them at the top of this page. Their purple/reddish look is very unique and satisfying.
Our red onions that you see in the picture were very easy to grow and required little care or maintenance. Read on to find out how we started them from seed!
What Are Some Easy Ways to Plant Onion Seeds?
Since I began growing onions, I have started our onions indoors in a seed tray in late winter – specifically, somewhere around 12 weeks before my last frost date. I use a homemade potting mix of 4 parts peat moss, 1 part vermiculite, and 1 part perlite. I also add some of my own worm castings to the mix. You can sprinkle multiple onion seeds into each cell of your seed tray. Onions are very hardy and don’t mind being planted close together! I put them under a grow light in my basement. Check out our Best Seed Starting Products page for help with getting you starting with this process!
I plant my onions outside once the ground has thawed and the soil can be worked. Onions don’t mind the cold weather and can handle a frost. The onions are bundled close together as mentioned in the method I described above. Onions are strong, so you can just pull apart each individual onion and plant them in the ground. Leave the white bulb part of the onion just at soil level. It’s really hard to mess this up because onions are pretty hard to kill!
You can also try starting your onions from seed outdoors to avoid the need to transplant. I have not tried this method myself yet, but I definitely am going to try! You can plant the seeds in your soil in the fall, cover with mulch, and they will come up next spring. Onion seeds will do fine even during a cold and frozen winter! You can also wait until late winter or early spring to plant seeds outside.
“Through him all things were made; withoutJohn 1:3
himnothing was made that has been made.”
When Are My Onions Ready to Harvest?
This is pretty much the easiest part in my experience. Onions will tell you when they are ready! Well, they don’t actually speak, but the green tops of the onions will begin to fall over when they are ready to be harvested. Once the crown or stem which is the part closest to the bulb starts to soften up, the onion can be pulled out of the ground.
At this point, it is important to dry out the onions for two to three weeks so they can be stored. This is called curing. Either hang them or lay them out on a screen in a place that is covered to ensure the onions do not get wet. We used a screen over top of a wheel barrow on our covered porch. Keep your onions out of the rain and have good airflow to dry them out!
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How long does it take to grow onions from seed? This mostly depends on the variety of onion you are growing, but onions generally take 110 to 175 days to form large bulbs. The specific amount of time will be shown on the back of your seed packet.
How many onions grow from one seed or set? Each seed or set that you plant will give you one onion bulb.