Most of what is sold as spring onion or salad onions are simply early-maturing varieties of onion. They should be grown quickly- in about eight weeks from sowing to harvesting- otherwise, they become tough. In culinary terms, the distinction between different types of spring onion is purely one of size- they vary from the really tiny(thinner than a pencil) spring onions to those that are as large as a baby leek. Some varieties of spring onion have a markedly bulbous base, no particular basal swelling.
Spring onions have a mildly sweet flavor with a fresh, green snap, which makes them good in salads and thicker ones for cooking. The leaves can be used as a substitute for chives. Red spring onions look pretty in salads but don’t differ significantly in flavor from white spring onion. Unlike ordinary onions, spring onions. Unlike ordinary onions, spring onions do not store well. They can be kept for a few days in a cool place or in a refrigerator, but are best used really fresh.