Jicama, often referred to as the Mexican turnip or yam bean (Pachyrhizus erosus), is a large, edible root vegetable valued for its crisp, succulent texture and mild, slightly sweet flavor. This tropical and subtropical crop is cultivated worldwide for its tuberous root, which is typically eaten raw in salads or cooked in stir-fries. Jicama requires a long, frost-free growing season to produce sizable, starchy tubers. Successfully growing this unique vegetable depends on understanding the precise moment to lift the root and how to preserve its quality afterward.
Identifying Maturity: Visual Cues for Harvest
Determining the exact time to harvest jicama involves observing visual indicators, signaling that the plant has completed its primary growth phase. The plant requires an extended period, typically five to nine months, or approximately 150 to 200 frost-free days, for the tubers to reach optimal size and sweetness. The most reliable external indicator is the yellowing and subsequent dying back of the vine foliage. This change signifies that the plant is naturally redirecting its energy and stored starches down into the underground tuber.
Gardeners must prioritize harvesting before the first predicted frost, as jicama is highly susceptible to cold temperatures. Even a light frost can compromise the quality of the underground roots, potentially leading to decay or a shortened storage life. The size of the tuber can be checked by gently brushing away the soil near the crown of the plant. A mature, high-quality jicama tuber should have a diameter of approximately four to six inches and feel dense and heavy.
Experienced cultivators often harvest the roots just before or immediately after the plant begins to flower and set seed pods. Allowing the plant to fully flower diverts energy away from tuber enlargement, resulting in smaller, less desirable roots.
The Physical Process of Digging Jicama
Once the visual cues confirm the jicama is ready, removing the root must be handled with care to prevent damage that could shorten its shelf life. A garden fork or pitchfork is the preferred tool, as a traditional shovel can easily slice or puncture the skin of the tender tuber.
Begin digging at a generous distance from the plant’s crown, ideally 12 to 18 inches away, to account for the lateral spread of the developing root. The goal is to loosen the soil surrounding the tuber rather than attempting to pry it directly from the ground. Insert the fork deeply into the soil and gently apply leverage to lift the entire clump, which minimizes the risk of bruising the jicama’s thin outer skin.
The skin’s integrity is a major factor in how long the root will keep in storage. After lifting the root, carefully shake or gently brush off the bulk of the excess soil while still in the garden. It is important to leave the skin completely dry and avoid washing the roots at this stage, as introducing moisture will drastically increase the chance of fungal growth and rot.
Curing and Storing the Harvest
Post-harvest handling is critical for preserving the crispness and flavor of the jicama. The roots benefit from a brief period of air-drying immediately after they are removed from the soil and brushed clean. This short “curing” involves placing the tubers in a warm, shaded, and well-ventilated location for two to three days. This allows the skin, or periderm, to harden slightly, offering better protection against moisture loss and pathogens during long-term storage.
Jicama is exceptionally sensitive to cold temperatures and must be stored in specific conditions to prevent chilling injury. The ideal temperature range for storage is a cool, dry environment between 55°F and 60°F (13°C and 16°C). Storing the roots below 50°F (10°C) can cause internal discoloration, decay, and a loss of the characteristic crisp texture.
Under these optimal cool and dry conditions, jicama can maintain its quality for several weeks, sometimes lasting up to two months. The tubers should be stored unwrapped and kept dry, as any trapped moisture encourages spoilage. Only wash the jicama immediately before it is peeled and consumed.
Important Safety Note on Jicama Plant Parts
Only the large, starchy tuber is a safe and edible food source. The remainder of the plant, including the leaves, stems, flowers, and especially the seed pods, contains rotenone, a potent, naturally occurring toxin. Consumption of these non-root parts can be highly hazardous to humans and livestock, as the concentration is particularly high in the mature seeds, which must never be ingested. After harvesting the edible roots, all remaining vegetative material, including the vines and any seed pods, should be carefully removed and disposed of to prevent accidental consumption.