Onion seed is notorious for being difficult to produce, short-lived and difficult to plant. “The seed is small and has a funny shape that doesn’t work well in most mechanical planters,”said Pete Zuck, onion product manager for Johnny’s Selected Seeds in Winslow, Maine.
The small size, irregular shape and lower germination rates, compared with other vegetables, makes crop consistency difficult. To improve yield, some growers are opting for pelleted seed, which is easier to plant and offers greater accuracy. The pelleting process reduces the shelf life of the seed so it must be planted in the year the seed is purchased.
“I am seeing a lot of movement toward pelleted onions away from raw seed,” said Luke Donahue, Northeast territory sales representative for Johnny’s Selected Seeds.
Some onion seed is primed to improve germination, but this also shortens the seed’s shelf-life. “It is not always known if a particular lot of seed is primed or not; often the vendor does not say one way or the other, so it’s best not to keep onion seed around for very long,” Zuck said.
Regardless of whether the grower chooses raw seed or pelleted seed, quality is imperative to growing a bountiful crop.
“Growers are looking for high-quality seed that has good disease resistance, high uniformity and pack-out of marketable onions and good yield per acre,” said Jeff Trickett, sales and marketing director at Bejo Seeds, Inc. in Oceano, California. “With professional seed companies, good germination is expected and guaranteed.”
Matching varieties geographically
Geographic location dictates the type of onions that can be grown.
“Growers are selecting varieties that have the correct attributes for their growing conditions and the market where they intend to sell,” Trickett said.
Onion bulbing is based on day length, and if the varieties aren’t matched to their adapted latitude, bulbs may not be produced. Short-day onions require 11 to 12 hours of sunlight, intermediate day onions need 12 to 14 hours and long-day onions need 16 to 17 hours of daylight to create a bulb for harvest.
Northern growers plant long-day varieties, southern producers choose short-day onions and areas that are in between both regions use intermediates. Overwinter varieties are planted in select locations.
After identifying the day length onion best suited for their area, growers then look for the onion types that best fit their market. “Vidalia types are big in the South, and white onions are popular in Latino cuisine,” Zuck said. “Storage onions are popular in the North, where the growing season is limited.”
Research and development
Onion breeders continuously work to improve their seeds.
“There is ongoing research to improve on existing material to increase disease resistance and to produce better onions in all aspects,” Trickett said.
Breeders are working on improving specific characteristics for seed varieties based on the challenges specific to the region they are grown. For example, with long-day onions, breeders are developing varieties that may be better in storage, whereas for short-day onions (Vidalia onions, for example), the focus might be on flavor and mildness.
Zuck said that seed breeders also focus efforts on improving a wide range of features including:
- disease resistance
- thin necks, which allow for faster drying
- upright tops, for easier cultivation and prevention of soil-borne diseases
- bolting tolerance (for overwintering varieties)
- single centers (for making better onion rings)
- skin quality
- germination and seedling vigor
- cold and heat tolerance
- ability to reliably produce a seed crop
Insect tolerance also may be a major consideration. Thrips are a problematic pest in many areas of the country.
Some onion seed varieties can endure the pest pressure better than others. Seed development is also important for organic growers who have fewer tools for dealing with pest and disease problems.
“Bejo does not use GMO in any of our varieties, but we do use [the] latest technology such as genetic markers to help speed up the natural breeding process,” Trickett said. “This means combining the best onion lines with highest probability of resulting in desirable traits for growers.”
Bejo Seeds and Johnny’s Selected Seeds share the most popular selling varieties for each of the major onion growing areas in the U.S. The list on the next page only highlights the top few varieties for each type of onion in general geographic areas.
Read more: 7 tips for growing your best onion