you’re lucky, you might get very small onions.
Intermediate-day varieties are in the middle, and are ideal for gardeners in the middle latitudes of the U.S., but can typically be grown successfully by most continental U.S. gardeners not at the extreme north or south points of the country.
2. Sweet vs. Storage Onion Types
Onions are bred for varying degrees of pungency, moisture, and skin thickness. These three things in combination plus growing conditions and curing quality account for how well an onion will keep.
Sweet onions, like our famous local Walla Walla Sweets from Washington, or Georgia’s (also famous) Sweet Onions, are absolutely delicious for fresh eating. They are low in pungency, high in sugars, juicy and mild. They are not, however, great keeping onions.
Storage onions like Copra are drier and higher in the sulphurous compounds that give onions their punch. Lower moisture and higher pungency mean longer-keeping potential. A tight, small neck and close, protective skins help keeping onions dry and cure well, and limit the potential for rot in storage.
In addition, all varieties of bulb onions can also be harvested early in their growth to use as spring onions. Spring onions are tender and mild, with a small bulb and tender, scallion-like greens. I often deliberately plant my onions a bit close, and yank every-other-onion before they start to crowd each other. The thinned onions are delicious as spring onions.
3. Selecting an Onion Variety
Selecting a variety is easier once you’ve narrowed it down to varieties that suit your latitude. Within that framework, if your goal is a delicious fresh eating onion you can slice and add to summer barbecue burgers, go with a tender sweet type. If you want something you can cure and tuck away and count on for cooking all winter long, grow a dedicated storage type.
Hot tip! Sweet onions don’t actually make the best sweet, caramelized onions. Plain ol’ yellow onions are best for caramelizing onions like a pro.
The seed catalog or purveyor you are buying from should clearly specify both the day-length and the keeping-quality of their onion options. If they do not – go buy from somebody else. I mean it!
If you are an urban gardener or otherwise short on space, concentrate on growing fresh-eating sweet onions. The flavor difference on a truly fresh, just harvested homegrown sweet onion is up there with snap peas and corn. You’d have to taste it to believe it. Also, there’s a bit of an art and science to properly finishing and curing onions so that they will last as long as possible. If land is limited, outsource this task to your friendly local onion farmer.
If you have the land and the inclination, growing both a sweet variety and a storage crop of onions will pay off for the entire year, and it sure feels like an accomplishment to cook an onion you pulled out of the ground eight months earlier!
Specialty onions like cippolini and non-globe onions are worth considering if you are primarily interested in unique vegetables and flavors. I tried growing cipollini three years in a row and was not overly impressed in the yield-to-effort ratio compared to the globe types I grew.
Up here where I can high-five Canada, I only grow long-day varieties of onion. If any of you more southern readers want to chime in with your favorite sweet and storage varieties of onions in the comments, please do!
I’ve had great luck with the following varieties:
Recommended Long-day Storage Variety Onions
- Copra – The standard in yellow storage onions, these have stored very well in years when I’ve been diligent about about knocking down the tops and curing them well.
- Red Wing – A long-lasting red onion with great color.
Recommended Long-day Sweet Variety Onions
- Walla Walla – The best onion in the entire world, I’ve regularly grown sweet Walla Wallas that hit 2 pounds or more. Eat them first since they aren’t a great keeper.
- Ringmaster – A white Spanish type, I don’t think Ringmaster is quite as delicious as Walla Walla, but it’s mild and sweet and does last a bit longer.
4. Growing from Seed, Set 