What Are The Largest Onion Varieties? (10 Big Onion Varieties)


When it comes to growing onions, you may want to go big or go home.  If that describes you, then you’ll want to check out this list of 10 large onion varieties.

So, what are the largest onion varieties?  The largest onion varieties include Ailsa Craig, Expression, Kelsae, Rossa di Milano, Scout, Sierra Blanca, T-448, Walla Walla, Yellow Granex, and Zoey.  With proper care, these onions can grow to a diameter of 4 to 6 inches and a weight of one pound or more.

Of course, the type of onions you can grow will depend on where you live.  You will need to pay attention to short-day (grows well in the south), long-day (grows well in the north), or day-neutral (grows well anywhere).

In this article, we’ll get into detail about 10 of the largest onion varieties.  We’ll also talk about short-day, long-day, and day-neutral onions and which you should choose.

Let’s get started.

What Are The Largest Onion Varieties?

The largest onions varieties include:

  • Ailsa Craig
  • Expression
  • Kelsae
  • Rossa di Milano
  • Scout
  • Sierra Blanca
  • T-448
  • Walla Walla
  • Yellow Granex
  • Zoey
red onions
Red onions are “hotter” than white or yellow onions and last longer in storage.

As long as they get proper care, all of these varieties have the potential to grow to a colossal size.  Let’s dive into the details for each one, starting with Ailsa Craig.

Ailsa Craig

Ailsa Craig onions are open-pollinated.  They are a long-day variety, meaning they grow best in the north (adapted to latitudes 38 to 60 degrees).

ailsa craig onion
An Ailsa Craig onion –
they can get quite large!
Image courtesy of:
MOs810 via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Cebula_cukrowa_Ailsa_Craig.jpg

They have a mild flavor and can grow quite large, with a diameter up to 8 inches and a weight of 6 pounds!

The bulbs are yellow and globe shaped, maturing in about 110 days.  Ailsa Craig onions will last less than 3 months in storage, so they are best used for fresh eating.

You can learn more about Ailsa Craig onions from Dixondale Farms.

You can find Ailsa Craig onions from Johnny’s Selected Seeds.

Expression

Expression onions are hybrids.  They are an intermediate-day variety, meaning they won’t grow as far north as long-day varieties, nor as far south as short-day varieties (adapted to latitudes 32 to 45 degrees).

They have a mild flavor and can grow quite large, with a weight of 1.5 pounds!

The bulbs are light brown and globe shaped, maturing in about 105 days.  Expression onions will last 3-4 months in storage, so they can be used for fresh eating or for short-term storage.

You can learn more about Expression onions from Fedco Seeds.

You can find Expression onions from Johnny’s Selected Seeds.

Kelsae

Kelsae onions are heirloom and open pollinated.  They are a long-day variety, meaning they are best adapted to northern latitudes.

They have a mild and sweet flavor and can grow quite large.  In fact, one of the largest onions ever grown was a Kelsae onion, weighing 16 pounds, 8.5 ounces!

The bulbs are light yellow and globe shaped with white flesh, maturing in about 110 days.  Kelsae onions are sweet and will last less than 3 months in storage, so they are best used for fresh eating.

You can learn more about Kelsae onions from W.H. Perron.

You can find Kelsae onions from West Coast Seeds.

Rossa di Milano

Rossa di Milano onions are an open pollinated Italian heirloom.  They are a long-day variety, meaning they are best for northern climates (adapted to latitudes 38 to 50 degrees).

They have a sweet and pungent flavor and can grow quite large, with a diameter of 4 inches or more!

The bulbs are reddish purple and grano shaped, maturing in about 100 days.  Rossa di Milano onions will last over 6 months in storage, so they can be used for long-term storage.

You can learn more about Rossa di Milano onions from West Coast Seeds.

You can find Rossa di Milano onions from Johnny’s Selected Seeds.

Scout

Scout onions are hybrids.  They are an intermediate-day variety, meaning they won’t grow as far north as long-day varieties, nor as far south as short-day varieties (adapted to latitudes 32 to 46 degrees).

They have a mild flavor and can grow quite large.

The bulbs are light yellow and globe or grano shaped, maturing in about 107 days.  Scout onions will last 3-4 months in storage, so they can be used for fresh eating or for short-term storage.

You can learn more about Scout onions from Stokes Seeds.

You can find Scout onions from Johnny’s Selected Seeds.

Sierra Blanca

Sierra Blanca (Super Star) onions are hybrids.  They are an intermediate-day variety, meaning they won’t grow as far north as long-day varieties, nor as far south as short-day varieties (adapted to latitudes 32 to 45 degrees).

They have a mild flavor and can grow quite large, with a diameter of 4 inches or more!

The bulbs are white-skinned and globe shaped, maturing in about 109 days.  Sierra Blanca onions will only last 1 month in storage, so they are best used for fresh eating.

You can learn more about Sierra Blanca onions from Jung Seed.

You can find Sierra Blanca onions from Johnny’s Selected Seeds.

T-448

T-448 onions are hybrids.  They are a long-day variety, meaning they grow best in northern latitudes (adapted to latitudes 50 degrees or higher).

They have a mild flavor and can grow quite large.

The bulbs are bronze and globe shaped, maturing in about 95 days (265 days if planted in fall in the north).  T-448 onions will last 1-2 months in storage, so they are best used for fresh eating.

You can learn more about T-448 onions from Logan Zenner Seeds.

You can find T-448 onions from Johnny’s Selected Seeds.

Walla Walla

Walla Walla onions are open pollinated.  They are a long-day variety, meaning they grow best in northern latitudes (adapted to latitudes 35 to 55 degrees).

They have a mild flavor and can grow quite large, with a diameter of 4 inches or more!

The bulbs are yellow to light brown and globe shaped, maturing in about 125 days.  Walla Walla onions will last less than months in storage, so they are best used for fresh eating.

You can learn more about Walla Walla onions from Gurney’s.

You can find Walla Walla onions from Johnny’s Selected Seeds.

Walla Walla onions also come in a sweet variety, which you can find here.  You can sow this variety in late summer and winter them over (harvest in 300 days).

Yellow Granex

Yellow Granex onions are hybrids.  They are a short-day variety, meaning they grow best in southern latitudes (adapted to latitudes 20 to 36 degrees).

They have a mild and sweet flavor and can grow quite large, with a diameter of 5 inches or more!

The bulbs are light yellow and (flattened) globe shaped, maturing in about 140 days.  Yellow Granex onions are not recommended for storage, so they should be eaten right away after harvest.

You can learn more about Yellow Granex onions from Dixondale Farms.

You can find Yellow Granex onions from Johnny’s Selected Seeds.

Zoey

Zoey onions are hybrids.  They are an intermediate-day variety, meaning they won’t grow as far north as long-day varieties, nor as far south as short-day varieties (adapted to latitudes 32 to 45 degrees).

They have a mild flavor and can grow quite large, with a diameter of 4 inches or more!

The bulbs are light brown and globe shaped, maturing in about 107 days.  Zoey onions will last 3-4 months in storage, so they can be used for fresh eating or for short-term storage.

You can learn more about Zoey onions from West Coast Seeds.

You can find Zoey onions from Johnny’s Selected Seeds.

What Is The Largest Onion?

According to the Guinness Book of World Records, the largest onion weighs 18 pounds, 11.84 ounces (8.5 kilograms).  Tony Glover in the UK grew this onion of mammoth proportions.

Of course, most onions won’t get quite so large.  However, it is possible to get onions with a diameter of 3 to 4 inches in your home garden.

onion plants
Onion bulbs can grow to a diameter of 6 inches, but most will be less than 4 inches wide.

Big onions are more likely if you grow some of the largest onion varieties mentioned above.  However, the right onion will depend on your location and latitude (north or south).

The following table provides a summary of 10 large onion varieties and where you might have success growing them.

Onion
Variety
Day
Type
Suitable
Locations
Ailsa
Craig
long
day
northern
(latitude
38 to 60)
Expressionintermediate
day
middle
(latitude
32 to 45)
Kelsaelong
day
northern
Rossa di
Milano
long
day
northern
(latitude
38 to 50)
Scoutintermediate
day
middle
(latitude
32 to 46)
Sierra
Blanca
intermediate
day
middle
(Latitude
32 to 45)
T-448long
day
northern
(latitude
50+)
Walla
Walla
long
day
northern
(latitude
35 to 55)
Yellow
Granex
short
day
southern
(latitude
20 to 36)
Zoeyintermediate
day
middle
(latitude
32 to 45)
Large onion varieties with their type
(short, intermediate, or long-day)
and growing locations.

Remember:

  • Short-day onions will start to form a bulb when there are 10 to 12 hours of daylight. They are suited for southern latitudes.
  • Intermediate-day onions will start to form a bulb when there are 12 to 14 hours of daylight. They are suited for middle latitudes.
  • Long-day onions will start to form a bulb when there are 14 to 16 hours of daylight in a day. They are suited for northern latitudes.

You can learn more about how big onions get in my article here.  You might also be interested in learning more about how to grow larger onions in my article here.

You can find even more large onion varieties in this helpful chart from Johnny’s Selected Seeds.

Conclusion

Now you have a starting point for selecting onion varieties if you want to grow huge onions.  You also know which ones will be best for the area you live in.

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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