Here in Texas, SHORT day onions are the proper onions to grow. Short day onions will bulb here where the days are shorter than in the north. Northerners grow long day onions. There is also an Intermediate onion for central states.
This is the bag of onion bulbs that Atwoods sold me. I closely examined the label, but nowhere did it state whether these were long or short day onions. I figured that surely the garden supply buyer for a big outfit like Atwoods would have a basic understanding of what to buy for this region of the country. WRONG. So I bought the onions and when I got home I looked on the onion’s website. Well, the website said these were long day onions! So I printed out that page and showed it to the clerk when I returned the onions next time I went to town.
What this means is that you have got to realize that merchants don’t always know or care what they sell you and you need to know what will really grow in your area. Get the right onions if you want them to mature with bulbs.
Long day onions need 14+ hours of light a day to start forming that bulb. Intermediate onions need 12-14 hours of daylight to bulb and short day onions need 10-12 hours of daylight to bulb.