The walking onion, also known as the Egyptian Tree Onion or Topsetting Onion, is a perennial member of the Allium family that has captured the attention of gardeners due to its unusual name. This plant’s moniker comes from its remarkable method of self-propagation, which allows it to gradually “walk” across a garden bed over time. This hardy vegetable offers continuous harvests.
Defining the Walking Onion
This unusual plant is botanically classified as Allium x proliferum, representing a natural hybrid between the common onion and the Welsh onion. This variety is a true perennial, surviving the winter and returning year after year, often thriving in cold hardiness zones as low as 3. It forms dense clumps of thin, hollow green stalks, similar to scallions, which can grow up to two feet tall. The walking onion provides three distinct edible parts: underground clusters of small, pungent bulbs; green leaves and stalks used like chives; and aerial bulbils, or top-sets, which form instead of a flower.
The Mechanics of “Walking”
The process that gives the walking onion its name is a form of vegetative reproduction called vivipary. Instead of producing seeds, the plant forms a cluster of miniature bulbs, or bulbils, at the top of its stem. These top-sets grow larger, sometimes sprouting secondary clusters. As these bulbils mature, their collective weight becomes too heavy for the stalk to support.
The stalk bends over, lowering the cluster of bulbils to the ground. Once the bulbils touch the soil, they quickly develop roots and establish themselves as new, independent plants. Because the new plant is rooted a short distance from the parent, the clump appears to have taken a small “step,” slowly migrating across the garden over several seasons.
Culinary Uses and Harvest
Every part of the walking onion is edible, offering a sharper, more intense flavor than most common scallions or chives. The young green shoots can be snipped throughout the growing season for use in salads or as a garnish. The flavor profile of the green tops is often described as a blend of garlic and onion.
The aerial bulbils, which mature in summer, can be harvested while still firm and are frequently used as a substitute for shallots or pearl onions. These top-sets are popular for pickling due to their small size. The underground bulbs can be harvested in late summer or fall, much like multiplier onions, but are pungent and usually cooked rather than eaten raw.
Planting and Care
Walking onions are easy to grow and require minimal attention once established. They are most commonly propagated by planting the bulbils harvested from the top-sets, or by dividing the mature underground clump. The best time to plant the bulbils is in the late summer or fall, setting them about an inch deep in the soil.
These hardy plants prefer full sun exposure but tolerate partial shade, thriving in average, well-draining soil. As a perennial, the plant acts as a permanent fixture, providing a continuous harvest. It is only necessary to divide the underground bulbs every few years to manage the size of the clump.