The decision to cut the green tops off your onions is directly tied to the goal of long-term storage. The “tops” refer to the green foliage that grows above the bulb. While attached, they serve as the plant’s nutrient-gathering system. Removing this foliage after harvest ensures the bulb remains firm and flavorful for months.
Why Cutting the Tops is Necessary for Storage
The primary reason for trimming the foliage is to create a sealed environment for the bulb. When onions are pulled from the ground, the neck—the area where the green top meets the bulb—is still moist and open. This moisture creates an easy pathway for decay-causing pathogens, such as mold and bacteria, to enter the bulb tissue. Leaving the tops attached means the bulb remains connected to a source of moisture and organic material, which accelerates spoilage during storage. Removing the foliage at the right time encourages the neck tissue to dry out and constrict, forming a natural, papery, protective seal around the top of the bulb, locking out external contaminants and extending the shelf life of the harvest.
The Timing of Cutting
The success of long-term onion storage depends entirely on the correct timing of this cut. The tops should never be cut immediately upon harvest while the foliage is still green and fleshy. Cutting a green neck leaves a large, open wound on the bulb, which significantly increases the risk of rot because moisture and pathogens can easily infiltrate the layers.
The entire plant must first undergo a curing period, typically lasting from one to three weeks in a warm, dry, and well-ventilated space. During this time, the green tops and neck must be allowed to thoroughly dry out. The sign that curing is complete is when the neck is completely shriveled, brittle, and papery to the touch. This change indicates the conductive tissue has died back and the bulb has formed its protective outer skin.
Waiting until the neck is fully dry ensures that the natural seal has formed before the top is removed. If the neck still feels soft, slick, or moist, the curing process is not complete, and cutting should be delayed. Premature trimming bypasses the natural sealing mechanism, which leads to poor storage and a high percentage of bulbs developing soft rot.
How to Properly Trim the Onion Tops
Once the neck has achieved that dry, papery texture, you are ready to trim the tops for final storage. The technique focuses on maintaining the integrity of the newly formed seal. Use a pair of sharp, clean shears or scissors to make a precise cut.
The cut should not be made flush with the bulb itself. It is important to leave a minimum of one to two inches of the dried neck material attached to the onion. This remaining stub acts as a physical buffer, protecting the delicate top layer of the bulb from potential damage.