Growing an onion is not as simple as seeds, soil, water, and sun. There is some serious science behind seed types and growing regions.

We sat down for a fascinating conversation with seed specialist Zach Wortiska, a California Business Sales Manager at Seedway, to learn more about onion varieties and the science of seeds.

“Producing a new type of onion can take 8 to 15 years,” Wortiska said, “A lot is going on behind the scenes, from seed trials to growth testing. We’re always working to improve the onion varieties we have.”

Seed Specialization: Finding the Best of the Best

Wortiska and his team work closely with growers and farmers to understand what onions different markets need. They look closely at characteristics of ideal onions and work to consistently produce high-quality crops. Onion characteristics have a wide range of variety and purposes:

Shape

Different shapes work for different reasons — a globe shape is best for markets and in-person shopping, while flatter onions are sometimes associated with less pungency. Seed specialists work to avoid tall, long onion shapes.

Color

Different colors serve different purposes as well. Yellow onions are preferred for cooking, red onions bring flavor to grilled dishes and pickling recipes, and white onions are often used for garnishing. 

Size

If an onion is going to be processed, a large size is ideal. For markets and consumers, medium to large will work.

Flavor

The flavor of onions can vary from mild to strong, sweet to sharp. Each flavor profile is uniquely suited to different recipes and purposes.

Producibility

One factor that might be overlooked by consumers, but is essential to consider as a seed scientist, is producibility. This refers to how well a line of onions produces seed, so growers are able to efficiently replicate that variety.

Center

All onions are more desirable with a single center, but some varieties end up with two or even three cores. 

Other factors that go into variety production include how prone an onion type is to developing disease and how well it can withstand pests. There are so many attributes being considered as new onion varieties are developed!

How Growing Regions Affect Varieties

Onions are a photoperiodic plant, which means they’re influenced by the number of daylight hours they experience. There are three main types of onion varieties: short-day, intermediate-day, and long-day, which refers to the hours of daylight they need to trigger the onion bulb to develop. You can’t plant one of these varieties in the wrong region and just hope for the best — they each have specific needs relating to climate and sun exposure.

Short-Day Onions

Short-day onions typically need 11 to 12 hours of daylight for optimal growing conditions. These onions are grown in Southern California or Texas and often prefer mild winter climates (Zone 7 or warmer). Typically short-day onions are planted in the fall or winter and will reach maturity during the spring months. If these onions are planted north of the Mason-Dixon Line, their bulbs will never fully develop.

At Gills Onions, we use short-day onions grown in the Imperial Valley in California. Some short-day onions include Sweet Red, Georgia Sweet, Texas Sweet White, Red Creole, Vidalia, White Bermuda, Walla Walla, and others.

Intermediate-Day or Day-Neutral Onions

Intermediate-day onions are often referred to as day-neutral because they can handle a range of growing conditions. This makes them a more adaptable type of onion variety. They typically do best with 12 to 14 hours of daylight to form optimal onion bulbs, which puts their prime regions in Zones 5 and 6. The San Joaquin Valley grows intermediate-day onions, which are typically planted in the spring. 

We grow our intermediate-day onions in the Central and Salinas Valleys of California. Some intermediate-day onion types are Candy, Super Star, Sweet Red, Australian Brown, and Red Candy Apple.

Long-Day Onions:

Some onions need 14 to 16 hours of daylight to form bulbs, classifying them as long-day onions. These are grown in more northern and colder regions, like the Pacific Northwest and Northern California. These onions need more space in addition to more hours of sunlight and form a larger bulb. These are the best onions for storage, and they’re typically harvested at the end of summer.

Long-day onions include Purple Haze, Caliber, Ruby, Sweet Sandwich, and Stuttgarter.

Seed Science Partnerships

“Creating onion varieties is a long process,” said Wortiska. “We work closely with growers and customers to understand long-term goals and improve the varieties of onions that we have.”

As varieties are produced, they start with small seed trials before moving to larger and larger outdoor growth trials. 

“Growing these new varieties in fields really is quite the sight to see,” Wortiska said. “We’re invested in making these work well for different markets, and we want to help farmers have what they need.”

Want to learn more about onions grown “The Gills Way?” Check out this post all about how onion seeds are produced.