I have not planted onions in a long time, would like to try a row or 2.
Is it too late in the winter?
Will a Vidalia type mature before bolting, in Stone Mtn? if planted in the next few weeks.
Or should I just wait until next fall early winter?
If you want a Vidalia type it's late and they will mostly likely not do well that far north even if they were planted earlier. Long day onions would be fine planted this time of the year and would be better suited for your area.
I've always planted mine early spring when the soil is first workable. Never had an issue making good bulbs. I always buy whatever sets the local feed store gets in.
I bought some sets from a place that are a super sweet Texas type. They are healthy enough to only have about 50 per 1.5 lbs. Planted a few lbs last year March 17th. Pic below was April 15th and you can already see bulbs getting decent size. They were plenty big enough late May/early June.
I never realized onions need a good bit of nitrogen in the early stage. You want as many green stalks as possible before they start bulbing. I've read that each stalk basically equates to a layer in the onion. I think you would be better served with a short or intermediate day variety. I start mine from seed in my garage. This year I started some in October and planted out Dec 21, some I started early Dec and planted out a couple days ago, and some I started Jan 12 and will plant out 2nd week of March. Trying to see if one batch does any better than the others.
Also, onions do not like competition at all! You have to keep them clean from weed competition and also keep the dirt very loose around the bulb while they grow so they don't have to fight to break the soil.