Popular in Latin America and tropical regions of Asia, the perennial jicama (Pachyrhizus spp.) produces a crisp, sweet, white-fleshed tuber root tasty in culinary dishes. Grow it from seed or from small developing roots in a hot, sunny part of the garden for harvest in fall before the first frost. If your climate's summer is at best only warm and lasts less than four months, consider buying roots at the market rather than growing your own.
Two species of jicama remain popular, differing only in the potential size of tuber roots: Pachyrhizus erosus and Pachyrhizus tuberosus. They hail from tropical America, from southern Mexico southward into South America's Amazon River basin.
Jicama develops viney stems that reach lengths of 10 to 20 feet. Its green leaves comprise three heart-shaped leaflets, just like other members of the bean family. In summer, stems bear white flowers that later develop into green bean pods numbering about six to a cluster. Underground, the tubers enlarge over the growing season or over several years, resembling elongated turnips or potatoes with a tan-colored skin. According to the University of Florida, in five months of growth tubers reach 6 to 8 feet long and weigh 50 pounds or more. Usually roots look round and beet-like with a distinctive taproot when grown for shorter periods in a vegetable garden.
Plant seeds or young roots of jicama when there is no threat of frost, preferably when soil temperatures no longer drop below 50 degrees Fahrenheit. To develop bigger roots worth harvesting, at least five to nine months of a long, warm to hot growing season is needed. Soil should be moist but well-draining such as a sand or loam rich in organic matter. Provide at least six to eight hours of direct sunlight daily. Removing flowers before seed pods develop tends to lead to better tuber root production.
All above-ground parts of the jicama plant contain the toxin rotenone and must not be consumed. All root tubers that do not emerge from the soil are safe to eat.
Remove the peel of jicama root, including the fibrous flesh directly under the skin. Cut or slice and serve raw or use as a substitute for water chestnuts in recipes. Jicama remains crisp after cooking, fried or sauteed, and it can be incorporated into Asian and Indian curry dishes.
In hot summer regions, jicama acts as a ground cover in the vegetable garden, as it is one of the few crops to tolerate oppressive heat and humidity and torrential afternoon thunderstorms such as the summer norm in peninsular Florida and other tropical regions.