Egyptian Walking Onions are an unusual perennial onion, Allium x proliferum.   They are a cross between Allium cepa, the cultivated onion, and Allium fistulosum, the Welsh onion.)  These are a top setting onion type which grows to about 2 feet tall (61 cm) and produces a cluster of bulbils, at the top of a sturdy stalk.  If the bulbils are left unharvested by late summer,  they will eventually fall over or "walk" and replant themselves.  In the fall and winter,  the onion plant will dry out naturally and become haggard looking.  Then in early spring, the onion shoots will regrow.  These perennial onion plants are hardy in zones 3-10.  

Egyptian walking onions are quite easy to propagate. Just break off the bulbils and plant! Place them no more than an 2.54 cm (1 inch deep) and 10-12 cm (4-5 inches apart). They can be separated easily but will grow as a clump very well. They don’t need to be replanted as the similar multiplier onions do. They also multiply from the base, so established clumps can be divided as well. This is best done in spring.