Allium × proliferum, Egyptian walking onions, tree onions, or top-setting onions. A wonderfully strange perennial onion that can provide years of harvests from a single planting. Use the tender green leaves like scallions, harvest the small underground onions like shallots, and eat or replant the clusters of miniature onions that form at the tops of the stalks.
 
They're called “walking onions” because the stalks eventually bend to the ground, allowing the top onions to root and start a new clump a short distance away.
 
Plant once and allow a patch to establish for a low-maintenance perennial supply of onion greens and small cooking onions. Very cold hardy and well suited to Pacific Northwest gardens.
 
Sun: Full sun to part shade
Soil: Fertile, well-drained soil
Spacing: 6–8 inches
Harvest: Greens fall through spring; topsets and bulbs in summer
Perennial: Yes
Edible parts: Leaves, underground bulbs and topsets

Available in 2" containers, with 1-2 bulbs, and 4" containers with 4-5 bulbs.