Garlic growers aim to harvest the largest possible bulbs. Achieving this goal requires strategic management of the plant’s above-ground growth, particularly knowing which parts to remove and which must remain untouched. The choice of whether to trim the leaves or the scapes significantly impacts the final size and quality of the subterranean bulb. Understanding the distinct biological roles of the scape and the foliage is essential for maximizing yield.
Why Scape Removal Is Essential
The garlic scape is the stiff, coiling flower stalk that emerges from the center of the plant, typically in hardneck varieties. If allowed to develop fully, this stalk produces a flower and tiny aerial bulbils (seeds), requiring a substantial investment of the plant’s resources.
When the scape appears, the plant redirects significant amounts of energy, specifically carbohydrates produced by the leaves, away from the developing underground bulb. This energy shift is a biological priority for the plant, aiming to ensure the next generation of garlic. Removing the scape interrupts this process, forcing the energy to be channeled back toward the storage organ.
Removing the scape can increase the final size and yield of the garlic bulb by 20% to 30%. This makes scape removal one of the most impactful management practices for hardneck garlic. The scape acts as a nutrient “sink,” and its removal results in a surplus of energy deposited directly into the bulb.
The Importance of Garlic Foliage
In sharp contrast to the scape, the green leaves, or foliage, of the garlic plant are the primary machinery for bulb development. These leaves function as the plant’s solar panels, capturing light energy to drive photosynthesis. This process converts carbon dioxide and water into glucose, which serves as the plant’s fuel and building material.
The glucose is converted into complex carbohydrates and moved down to the underground bulb for storage. The size of the bulb is directly proportional to the total photosynthetic capacity of the foliage. Therefore, trimming healthy leaves drastically reduces the plant’s ability to feed the bulb, resulting in a significantly smaller yield.
Cutting just one healthy leaf can reduce the overall yield. Studies indicate that removing the top two leaves can decrease the ultimate bulb size by as much as 25%. Leaves should be left intact until the natural process of senescence begins, when they start to yellow and dry out.
When and How to Trim
The timing and technique for trimming are crucial to ensure the intended benefit without causing harm to the plant. Scapes should be removed as soon as they emerge from the central stalk and have formed one full curl or loop. Waiting until the scape has fully straightened means the plant has already diverted substantial energy away from the bulb.
To remove the scape, make a clean cut close to the top leaf, taking care not to slice the surrounding foliage. A clean snap by hand is often preferred over shears, as this prevents accidental cuts to the leaves. A leaf should only be trimmed if it is diseased or heavily damaged, and this is done only to prevent the spread of infection.
The final stage of the trimming cycle relates to harvest timing, which is indicated by the foliage. The bulb is ready to be harvested when the lower third to half of the leaves have naturally turned yellow or brown. At this point, the plant has completed its carbohydrate production and the bulb is fully formed.