South of about 35N latitude we grow ‘short day’ onions the best. That means we don’t have the longer days in the summer they do in the north. Long day onions never do get the day l ength signal to make a bulb down here and will stay green onions.
I get the granex stuff in bulk here:
https://www.hpsseed.com/dp.asp?pID=02789&c=275&p=Yellow+Granex+Hybrid+Onion
Johnnys seed also has short day onions as well and tells you the optimum latitude for each variety in the description:
http://www.johnnyseeds.com/p-7390-pumba-f1.aspx (yellow vidalia type)
http://www.johnnyseeds.com/p-7393-desert-sunrise-f1.aspx (reddish/pink type)
http://www.johnnyseeds.com/p-8857-white-castle-f1.aspx (white onion type)
Baker creek has 2 varieties that I know of that will work in the south:
http://www.rareseeds.com/violet-de-galmi-onion/
http://www.rareseeds.com/red-creole-onion/
Onions will start out as a thin little green stalk that will multiply into several stalks and the ‘leaves’ will get thicker as it gets older. At some point the daylight hours will get long enough and it will stop producing leaves and start to make a bulb. The difference in long day, intermediate day and short day onions is the length of day that triggers this. If you plant long day onions in the south they’ll make beautiful green onions but little to no bulb because the days never get long enough to trigger bulb growth. If you grow short day onions in the north, the days will be long enough before the onion plant itself has sufficient size to produce a big bulb and you’ll get teeny bulbs instead. The size of the green plant part at the point that bulb growth is triggered is one of the things that determines the size of the onion you ultimately harvest.
I’d love to grow the ‘ailsa craig’ onions down here. Ain’t happening. They’re huge and very long keepers. Would be great onions to have. Unfortunately they’re not really happy south of about 45N lat as they’re a scottish variety. Ask me how I know this :P
YMMV, of course. I learned the onion lessons the hard way.
QUICK! Make a CD of your brain gardening information and mail it using one day mail to my address - I love you. :o)
I will copy all you put in that post and study it. The lowly onion appears to be complicated. Here is the onion seed I have:
Evergreen Bunching
Onion Parade (Bunching Type)
Borettana Cipollini
Yellow Sweet Spanish Utah
Since I haven’t read all your info. yet, do you know just off the top of your head, that the Sweet Spanish won’t grow right for me in Conroe, Texas, 40 miles north of Houston?