Bunching onions are a versatile and perennial member of the Allium genus, often known as scallions, green onions, or spring onions. These non-bulbing types, primarily Allium fistulosum, produce a cluster of long, hollow green leaves and a small, straight white base instead of a large, globe-like bulb. Understanding when and how to harvest them maximizes their mild flavor and sustained productivity. The ready-to-harvest stage can be reached through two primary methods: complete removal for a single yield or a strategic cutting technique for multiple harvests.
Visual Cues for Readiness
The time to harvest bunching onions is determined solely by the appearance and size of the stalk, as they do not form a traditional bulb to indicate maturity. A good general indicator is when the green tops have reached a height of at least six inches. The white base, which is the most tender part of the plant, should be about the thickness of a pencil, which typically translates to a diameter between one-quarter and one-half inch at the soil line.
Harvesting can begin at any point after the plants are established, but waiting until the base is pencil-thin provides the best balance of flavor and size. The texture of the green leaves should be crisp and smooth, and the flavor should remain relatively mild. If the plants are left in the ground for too long, they can begin to bolt, which means the plant prematurely sends up a thick, woody flower stalk.
Once bolting occurs, the energy shifts to seed production, and the quality of the edible stalk declines quickly. The central flower stalk that develops is tough and unpalatable, and the flavor of the onion becomes stronger and more pungent. The green tops may also start to yellow or become excessively tough, signaling the plant is past its peak tenderness.
Harvesting Methods for Single Use
Harvesting for a single, complete use involves removing the entire plant from the soil, which ends the life cycle of that stalk. This method is preferred when a recipe calls for the entire white base, including the root plate. The full plant is ready when the white shank has reached its desired thickness.
To perform a clean harvest, it is helpful to loosen the soil around the base of the plant using a hand fork or trowel before pulling. This step minimizes the risk of snapping the stem off at the soil line, ensuring the entire white portion remains intact. Gently grasp the base of the onion and pull straight up once the soil is sufficiently loosened.
After removal, the plant should be cleaned by trimming the roots close to the base with a sharp knife or scissors. Any papery or dead outer layers of the white stalk should be peeled away to reveal the clean, tender flesh underneath. This technique provides the largest possible single yield from the plant, but it requires replanting for a future harvest.
Harvesting for Continuous Yield
The most efficient way to harvest bunching onions is through the “cut-and-come-again” technique, which allows the plant to regenerate and produce multiple harvests from a single planting. This method relies on the perennial nature of the onions to maximize sustained production. The precise cutting location is the most important factor in ensuring rapid regrowth.
The green tops should be cut using a sharp tool, such as scissors or a small knife, leaving the white base and the root crown undisturbed in the soil. A cut made approximately one to two inches above the soil line is ideal, ensuring the plant’s growth point remains intact. Leaving this small section allows the plant to quickly draw on stored energy reserves to initiate new growth.
Following this strategic cut, the plant typically begins to show new growth within a couple of days. The stalks are usually ready for a subsequent harvest within one to two weeks, depending on growing conditions. This continuous harvesting process encourages the plant to tiller, or multiply its stalks, which leads to a larger bunch over time. This technique is recommended for gardeners seeking a steady supply of greens, as it maintains the health and productivity of the onion patch.