Walking onions are similar to common onions (A. cepa), but with a cluster of bulblets where a normal onion would have flowers. Genomic evidence has conclusively shown that they are a hybrid of the common onion and the Welsh onion (A. fistulosum). However, some sources may still treat the tree onion as A. cepa var. proliferum or A. cepa Proliferum Group. Tree onion bulblets will sprout and grow while still on the original stalk. They may bend down under the weight of the new growth and take root some distance from the parent plant, giving rise to the name “walking onion.” It has been postulated that the name “Egyptian onion” derived from Romani people bringing tree onions to Europe from the Indian subcontinent.
Harvest bulbils in late summer and replant immediately or store them in a cool dry frost-free place and plant them out in late winter or early spring. Division of the bulbs after the leaves die down in late summer.