Answer: One important thing to remember about onions is that there are two different classes: long-day and short-day onions. Long-day onions are more appropriate for northern states because they are adapted to longer days. Southern states should use short-day varieties of onions. When you go to your nursery, they will usually list long-day onions as L and short-day onions as S. Short day onions develop bulbs with an average of about 12 hours of daylight. Long-day onions form bulbs with more sun, around 15-16 hours of daylight. You should grow the kind of onion appropriate for your region to ensure proper maturation of the onion bulbs. Red onions are long-day onions so they new 15-16 hours of daylight in order to form bulbs. You didn't mention where you live so it's possible that your region is better for short day onions.
Hope this clarifies things for you!
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