If you haven‘t grown or eaten jicama, you should try it! It is easy to grow in the tropics and is an exotic snack or a delightfully moist, crunchy, sweet addition to salads. We grew jicama (pronounced “hee-kah-mah”) for years in northern Haiti and now find it just as happy in the soil and climate of our back yard in Kinshasa, Democratic Republic of Congo. It‘s not fussy; you just plant the seed and a few months later dig up the tubers. Our Congo soils are infested with nematodes, and our tomatoes struggle under an onslaught of spider mites. Jicama, though, grows as if there are no bugs around. That makes sense, as the vine contains its own built-in insecticide in the form of rotenone.
So what is jicama (Pachyrhizus erosus)? Native to Central America, it is also known as the Mexican Turnip or Yam Bean. The edible part is a large tuber that develops just below the surface of the ground (Figure 3). The rest of the plant is mildly toxic. Written descriptions of the tuber never adequately prepare you for the first bite. It is like an enormous, sweet radish, except crunchier and not at all hot, or like a carrot but with white flesh like a potato. Its texture is like water chestnut.
Jicama won‘t displace potatoes or cassava in your diet but will make a special addition to salads or an exotic vegetable for a meal. Jicama is mostly eaten fresh but can be pickled or cooked. It can be used as a substitute for water chestnut in stir fries because it retains most of its crunchy texture even with mild cooking. Served fresh, it is sliced, diced, or cut in sticks. It does not discolor after slicing. Harvested early, fresh jicama is about 90% water. It is high in Vitamin C and fiber. If allowed to mature in the ground, the tubers become higher in starch.
Jicama is normally grown from seed and develops into a climbing vine (Figure 4). We usually trellis the vines to make room for other plants in the garden. At ECHO the vines are allowed to run as a ground cover. Jicama needs hot weather but not much water. The plant requires short days to form tubers. Hence, farmers in the tropics do not need to worry about competition from temperate regions. [Editors: At ECHO, jicama that is planted during the longest days of the year, May through July, begins to form tubers only when the days become very short. They are typically harvested in January. If planted later the plants only grow to about 2 feet tall.
We harvest the tubers for home consumption when they are 8 to 10 cm (3 to 4 inches) in diameter. At that stage they have a nice round, onion shape and are easy to peel and slice. They can grow up to a foot in diameter and weigh over 22 kg (50 pounds), but these large tubers are less appealing because they tend to be odd shaped and starchy. The tubers store well at room temperature in the tropics for several weeks. They store for several months when refrigerated.
The only problem we had growing jicama in Haiti was loss of the seed. Seeds didn‘t store well at room temperature. If you grow and like jicama, keep growing it regularly to keep a stock of fresh seed on hand. The seed are easily harvested from dry pods. Jicama is not weedy, but an abundance of seed can be produced in a few months if you have the discipline to not dig up the vines for the tubers.
The seeds are inedible because they contain rotenone.
In places where it is not yet widely grown (such as Kinshasa), jicama has the potential to be a major source of income to specialty vegetable growers. Try growing jicama—you‘re sure to succeed in the hot, humid tropics and you‘ll no doubt fall in love with it as we have.
Jicama seed can often be found in local markets in Southeast Asian and Latin American countries. Ask around in places where you see the tubers sold.
Niles, W. 2009. Jicama. ECHO Development Notes no. 102