When do onion plants form seed stalk?
Onion plants grown from seeds rarely form seed stalk unless they are severely chilled by heavy frosts or freezing temperatures. Onions from sets generally form seed stalks only when individual sets are larger than 3/4 inch in diameter when planted. Harvest plants that start to form seed stalks and use for green onions or break off seed stalks immediately and use full size onion fresh – do not store it.
