Garlic is a long-season, cool-climate crop that requires an overwintering cycle, planted in late autumn and harvested the following summer over eight to ten months. This extended timeline is necessary because the plant needs the cold temperatures of winter to complete the fundamental biological process required for proper bulb development. Planting in the fall ensures the developing cloves are exposed to the necessary chilling period to initiate growth.
The Necessity of Vernalization
Garlic must be planted before winter due to vernalization, a physiological requirement. Vernalization is the process where prolonged cold temperatures trigger the division of the central clove. Without this cold signal, the single planted clove will fail to form a segmented bulb with multiple cloves.
Garlic needs six to eight weeks where temperatures remain consistently below 40°F (4°C). This chilling period signals the plant’s growth point to transition from vegetative growth to reproductive differentiation. Insufficient vernalization often results in a non-dividing, single-clove bulb known as a “round.” Gardeners in warmer climates often mimic this process by pre-chilling cloves in a refrigerator before planting.
The Full Growing Cycle
The timeline for growing garlic begins in late autumn, typically October or November, several weeks before the ground freezes. Planting allows the cloves to focus initial energy on root establishment throughout the late fall before the plant enters dormancy. During winter, the planted cloves remain largely dormant, anchored by established roots, enduring the cold exposure required for vernalization. Top growth is minimal, but the physiological changes necessary for bulb formation occur below the soil surface.
As soil temperatures rise in early spring, the plant emerges from dormancy and begins rapid vegetative growth, producing numerous flat leaves. Leaf development is important because the final size of the harvested bulb is directly related to the amount of foliage the plant develops before bulbing starts. Bulb formation occurs in late spring and early summer, driven by increasing temperatures and lengthening daylight hours. The plant’s energy shifts from producing leaves to swelling the underground bulb into distinct cloves.
The crop reaches maturity and is ready for harvest in mid-to-late summer, approximately eight to ten months after planting. A reliable sign that the garlic is ready to be dug up is when the bottom third to half of the plant’s leaves have turned yellow or brown and dried out.
Understanding Hardneck and Softneck Varieties
Garlic varieties are categorized into hardneck and softneck types, a distinction that influences planting success based on climate. Hardneck varieties are characterized by a stiff, woody central stalk, or scape, produced in early summer. These types are more cold-hardy and require a higher vernalization period, making them the preferred choice for regions with consistently cold winters.
Softneck garlic lacks this woody central stalk, allowing its leaves to remain pliable, which is why this type is often braided for storage. Softneck varieties require a less intense or shorter vernalization period, making them better suited for areas with milder or warmer climates. Softneck garlic is the type most commonly found in grocery stores due to its superior storage life, often lasting up to 9 to 12 months.