These Spring Onions are perrenial as they come up evey year. Not sure if they can be eaten (I imagine) however I generally use them for colour and to deter pests from other plants.... love the flower heads (which can also be eaten). This year I grew Spring Onion White Lisbon for eating (they are delicious) which I've planted in the ground and in containers. They grow better and faster in containers (probably as my ground isn't the most fertile).
This picture was taken in June; pictured left of the spring onion are sunflowers and left again, potatoes - all grown a bit too close together but I still got results. (see 11 August blog for how much the sunflowers grew in 2 months).