Seem to have heard my name called. I have grown onions from Virginia to Georgia, but skipped over North Carolina. I am confident that you can grow both long day and intermediate varieties with few problems. You should avoid the long storage type long varieties, But all the Sweet Spanish types should do well. The same would hold true for intermediate types like Candy. In each case, you need pencil size plants ready to go in the ground as the ground has thawed and is reasonably viable. Short day onions are best grown in Winter. I sow seeds around labor day and transplant in early December for harvest in May. Intermediate day plants and long day plants are transplanted in February.Harvest June -July. Long day onions are a problem for me some years because the cannot take some of our summer temps. Triple digits takes them down. In your area at higher elevation, summer temps should not be a problem, but winter temps may be a problem for short day types. They do not like to be frozen.
The third photo is Golden Grande long day sweet Spanish type. The others are short day
