Jicama is a crop almost nobody grows yet almost everybody enjoys once they taste it: a sweet, crisp tuber that snaps like a water chestnut and tastes like a mild, juicy apple. With a long, warm summer you can dig your own in fall, though it takes patience, because jicama needs five to nine months of heat to size up its roots, and only the tuber is safe to eat while the rest of the plant is poisonous. This guide covers every step, from starting seed indoors to feeding for bigger roots, harvesting at the right moment, and curing the tubers so they keep for weeks.
What Jicama Is and Where It Grows Best
Jicama (Pachyrhizus erosus), pronounced HEE-kah-mah, is a tropical vining legume in the bean family, native to Mexico and Central America and sometimes called the Mexican turnip or yam bean. The harvested root has the tan skin and white flesh of a turnip, but the resemblance ends at the plate: turnips taste peppery, while jicama is mild and faintly sweet. The plant climbs as a vigorous vine reaching 15 to 20 feet, and every part above the soil is toxic, leaving the underground tuber as the only edible portion.
As a warm-season crop, jicama grows best in USDA zones 7 through 10, where summers are long and hot. It wants full sun, at least eight hours a day, and soil that stays reliably above 50 degrees Fahrenheit, since sustained cold stalls growth. Like potatoes it is daylight sensitive, building vine and leaf during long midsummer days and shifting toward tuber formation as days shorten in fall, which is why it must go in early and stay undisturbed all season. Botanically a perennial, jicama is grown as an annual to lift the root; in frost-free regions a tuber left in the soil often resprouts the next spring, but anywhere that frosts it is replanted from seed each year.
Starting Jicama From Seed
Jicama has to be grown from seed. You cannot cut up a tuber and replant the pieces as you would a seed potato, and started seedlings are rarely sold. The seeds are large, flat, and roughly square, and a packet of around 25 lasts a couple of seasons; specialty and heirloom seed suppliers are the most reliable source, since big-box garden centers seldom stock it.
The seeds germinate slowly and unevenly, so give them a head start. Soak them in warm water overnight to soften the seed coat, then sow indoors about eight to ten weeks before your last expected frost. Warmth is the biggest factor: set the trays on a seedling heat mat and aim for a soil temperature of 70 to 85 degrees Fahrenheit, because even after soaking, sprouting can take up to 20 days. A grow light keeps seedlings sturdy rather than leggy once they emerge. If your seed is old, pre-sprout it between damp paper towels and pot up only the seeds that show a root, a quick viability check that saves weeks of waiting on duds when the whole season hinges on planting early.
When and Where to Plant Jicama Outdoors
Move jicama outside only after all danger of frost has passed and the soil has warmed to at least 50 degrees Fahrenheit, hardening off indoor-started plants over about a week so the move does not check their growth. In the warmest zones you can also direct sow into the bed in spring, an inch deep, thinning the seedlings as they grow.
Space plants 10 to 12 inches apart, with about four feet between rows, and choose the spot carefully because the vines will be there all summer. Jicama needs a sunny, open position and a sandy loam that is fertile yet free-draining, with a pH of about 6.5 to 8.0. Heavy, wet clay invites root rot and produces small, deformed tubers, so if your ground is dense, work in several inches of compost or grow the crop in a raised bed. Most importantly, give the vine something to climb: left on the ground it sprawls over everything nearby, so install a sturdy trellis, cattle panel, or strong wigwam at planting time. The mature vine is heavy, so flimsy supports will not hold it, and training it upward keeps foliage off damp soil, improves air flow, and makes the patch easier to manage.
Growing Jicama in Containers and Short-Season Gardens
You do not need a long-summer climate to grow jicama, but outside zones 7 through 10 the enemy is running out of warm days before the tubers size up, so the whole approach in a cooler region is about buying time: start seed indoors at the early end of the window, keep plants on a heat mat or in a greenhouse until nights are dependably warm, and be ready to cover them on cold nights into fall.
Containers are the most flexible tool for a short season because you can move them. Choose a large pot, at least 12 to 16 inches across and ideally 18 inches or more deep, roughly seven gallons per plant, so the tubers have room to swell; breathable fabric pots keep the root zone from overheating. Fit the pot with its own trellis, fill it with a fertile, free-draining mix, and place it in the sunniest spot you have, shifting it into a greenhouse or sheltered corner as the weather cools. The tradeoff is upkeep, since potted plants dry out and exhaust their nutrients faster. Tubers grown in cooler regions or in pots tend to be smaller than those given a full tropical season, but a modest homegrown harvest is well worth the effort.
Watering, Feeding, and Pruning for Bigger Tubers
Jicama is not drought tolerant, so consistent moisture is essential while the vine grows. Keep the soil evenly moist, supplying roughly two inches of water a week and more in hot, dry spells, but never let it sit soggy. Water at the base in the morning with a soaker hose or drip line rather than wetting the foliage, since wet leaves invite fungal trouble and saturated soil causes root rot. About two weeks before harvest, stop watering so the tubers firm up and cure in the ground, which improves how well they store.
Feeding is where the most common advice goes wrong, and it pays to understand why. Because jicama is a legume, it fixes some of its own nitrogen, and adding more only pushes lush vine at the expense of the roots. Skip high-nitrogen feeds and use a fertilizer formulated for root crops, with more phosphorus and potassium than nitrogen, such as a 5-10-10 or 3-5-7 blend, since potassium in particular drives tuber development; feed once the plants are established and again partway through the season. The size and number of tubers come down to two things you control: season length and where the plant spends its energy. To steer that energy underground, pinch off the flowers as they appear so the plant does not waste resources setting toxic seed pods, and prune back excessive vine. Done well, a plant can yield several tubers; in a short season or without flower removal, you may get only one. Either way, aim for medium roots rather than giants, because oversized tubers turn woody and lose their crisp texture.
Pests, Diseases, and the Poison Problem
The same toxin that makes most of the plant inedible also protects it in the garden. The leaves, stems, flowers, and seeds contain rotenone, a naturally occurring insecticide, so established plants are rarely troubled by the aphids and pests that ravage neighboring crops. This cuts both ways: those parts are poisonous to people and pets, so keep children and curious animals from nibbling the foliage or seed pods, and never compost the pods in a cold pile where the toxin lingers. Chopping spent vines into a hot compost pile breaks the compounds down safely.
A few problems still warrant attention. Weevils occasionally feed on foliage and stems; pick off any you see and drop them in soapy water, and a band of diatomaceous earth on the mulch discourages them from climbing. Aphids can stop by and spread mosaic virus, which yellows leaves with a mottled bluish-green pattern and has no cure, so pull and destroy infected plants promptly. The disease most likely to ruin a crop is root rot from overwatering or poor drainage, which leaves tubers sunken and deformed, so well-drained soil and careful watering matter more than any spray. Bacterial blight, showing as small water-soaked spots on the undersides of leaves, is best avoided by watering at the soil rather than overhead and staying out of the bed when it is wet.
Knowing When and How to Harvest Jicama
Patience is the hardest part of growing jicama, and digging too early is the most common mistake, since the tubers do most of their swelling late in the season. Wait until the plant has had its full run, generally 150 days or more, roughly five to six months from transplanting. Three signals tell you it is time: the day count, once you are past about 150 days; the vine, when the foliage begins to yellow and die back; and, overriding everything in a cold climate, the calendar, because jicama is killed by frost and tubers left in frozen ground rot from the inside, so lift them before the first hard frost regardless of the day count. In frost-free regions you have more leeway but should still harvest before the roots grow oversized and woody.
To dig, follow each vine down to the soil, loosen the ground around it with a garden fork or trowel, and work carefully outward to avoid spearing the tubers, whose skin bruises easily. Lift the roots by hand once loose, cut away the vine, and brush off the soil. A well-grown plant may produce one to five tubers, typically three to six inches across, and the sweetest, crispest flesh comes from medium-sized roots.
Curing, Storing, and Eating Jicama
Stored correctly, jicama keeps for up to two months, but it is fussy about temperature. If you did not stop watering before harvest, cure the freshly dug tubers in a warm, dry place, ideally around 80 degrees Fahrenheit, for a week or two so the skin firms up. Do not wash them before storage, because surface moisture encourages mold; brush off the soil dry and rinse only when you cook. For storage, the target is cool but not cold, roughly 50 to 60 degrees Fahrenheit in a dark spot such as a heated basement, garage, or root cellar. This is the detail that trips up beginners: jicama is damaged below about 50 degrees, so a standard refrigerator is usually too cold for whole tubers and breaks them down over time. Reserve the fridge for pieces you have already peeled and cut, which keep about a week in an airtight container; for longer storage, dehydrate the flesh into chips, freeze prepared pieces, or pickle the tubers.
When you are ready to eat, peel off the tan skin and the tough fibrous layer beneath it to reach the crisp white flesh, which conveniently does not brown in the air, so you can prep it ahead. Enjoy it raw in sticks, salads, and slaws, seasoned Mexican-style with lime and chili powder, or cooked gently to keep its crunch; the one rule that never changes is to eat the peeled root and nothing else from the plant.
Growing jicama asks for a long, warm season and patience, but few crops surprise a garden visitor the way a freshly dug tuber does. Start the seed early, give the vine sun and a sturdy trellis, feed it for roots rather than leaves, and lift the tubers before frost arrives. Order a packet of seed this winter, get it on the heat mat at the first opportunity, and plan for a crisp, homegrown harvest come fall.