Have you heard of oca before? Chances are you might have never tried it unless you’ve traveled in the Andes mountains, or have a great South American grocery store near you. It’s time to fix that.
Oca is a delicious, starchy tuber that gives you something a little different to eat or sell at the market from the usual potatoes that we all know and love.
If you’re fond of trying out new vegetables and would like to try cultivating them, read on! We have all that you’ll need to start growing oca in your own garden.
What is Oca?
Oca (Oxalis tuberosa) is a tuberous vegetable that’s indigenous to the Andes region. It grows prolifically throughout Bolivia and Peru, and is the second most popular edible tuber there, after the potato.
That said, it’s only recently gained popularity outside of South America. Many specialty grocers have begun to carry this delicious, waxy tuber to cater to our expanding palates. Hey, considering how nutritious (and tasty) these roots are, that’s hardly a bad thing!
Depending on where you travel, these roots can also be referred to as “apilla,” “quiba,” “papa roja” (red potato), “timbo”, “uqa,” or “hibias.” They’re absolutely delicious, and since the early 1800s, they’ve been naturalized in Europe, North America, Australia, and New Zealand, where they’re prized as delicacies.
Growing oca is a great idea if you’d like to expand your garden’s biodiversity. That said, it’s important to be aware that this vegetable can be very fussy to cultivate.
Oca Growing Requirements
First and foremost, in order for oca to develop its tuberous roots, it has to receive less than 12 hours of daylight. Furthermore, it needs to already be quite mature when this lack of sunshine occurs. It also needs fairly warm, consistent temperatures and humidity.
As a result, if you’re growing oca in the US, you’ll likely have the best luck if you’re in the Pacific Northwest. Anywhere other than that, and you’ll need temperature- and humidity-controlled greenhouse tunnels in order for your plants to thrive.
They don’t like too much direct sunshine either, and they’ll keel over and die in drought conditions. That said, they also need well-draining soil or their tubers will rot. (Did we mention that they’re fussy?)
Your best bet is to grow them in containers or raised beds. Fill these with well-draining, sandy potting soil such as cactus growing medium. These plants are heavy feeders, however, so work some well-aged compost into there too.
Furthermore, if you’re growing in raised beds, choose pots that you can move around easily. This is because you might need to transfer them between locales over the course of the growing season. Just know that you won’t get as many tubers in pots as you would directly in the ground.
Propagation and Planting
Growing oca tubers is pretty much identical to growing potatoes. Plant whole tubers a few inches into the soil after the last frost has passed. The plants spread out a fair bit, so plant them about a foot apart.
Many growers recommend saving the largest tubers from one year to the next. Then use those to start your next batch the following spring. Sure, smaller tubers will also grow into healthy plants, but the large ones will grow faster. They’ll also create more mini tubers, thus expanding your yield significantly.
If you only have a couple of large tubers but want to grow more plants, that’s not a problem. Tuberous propagation isn’t your only option when growing oca. They’ll grow really well from cuttings and slips. Just use a clean pair of snips to take cuttings that have at least a few leaves growing on them. Then keep those in clean water until roots form, and plant them as you would any other seedling.
You can earth up around the plants as they start to grow to increase their yields, but you don’t have to worry about the tubers going green. They don’t have arsenic like potatoes and won’t turn toxic with light exposure.
Watering and Feeding
When growing oca, make sure that their soil never dries out. They’ll pitch a fit and die on you in any kind of drought condition. Water them regularly, and check the soil daily to ensure that it’s sufficiently moistened.
If you live in a drier area, or if you experience a heat wave, consider adding some mulch around the stems. Straw or grass clippings will help to retain moisture so the soil doesn’t dry out too quickly. This will also keep the area cooler, which may help to calm down these temperamental tubers.
As mentioned, oca plants are heavy feeders. As a result, you’ll need to replenish the soil nutrients a few times over the growing season. Since you’re aiming for plump, healthy tubers rather than foliage, choose a low-nitrogen fertilizer. Then follow the instructions on the package
Potential Pests and Pathogens
Oca is remarkably free from both pests and pathogens. In fact, there are only two main culprits that you may encounter:
Not gonna lie here: these are complete bastards to contend with. They can stay dormant in the soil for years, and then attack your vegetables with great gusto. Few if any pesticides are effective against wireworms, so your best defense is a good offense.
Till your garden a good 10-12 inches down in the autumn, and then again in late winter or early spring. This should churn up larval worms and expose them. They’ll either freeze to death, or be eaten by birds, amphibians, moles, and other predators. Or both.
If you do find that you have a wireworm infestation, you can try fending them off with beneficial nematodes. Other than that, all you can do is pull up and burn affected plants.
Field mice, voles, and chipmunks seem to be quite fond of oca tubers. They’ll dig down into the soil to get to them and then chew chunks out of them. To prevent this, consider planting alliums such as chives or onions alongside your oca. They’ll help to fend off unwanted animal visitors, and will also attract beneficial insects.
Additionally, consider scattering predator poop such as cat, dog, fox, coyote, or wolf around the perimeter of your property. This will keep many rodents at bay for fear of becoming lunch. Growing oca tubers is difficult enough without ratty little mouths chewing on them.
Other Potential Issues
Not only are oca plants light-sensitive, but they’re also frost-sensitive. Quite simply, they’ll keel over and die at the first sign of frost.
Considering the fact that they won’t produce roots until the days are shorter (for example, in late November), that makes growing them successfully rather difficult. You may be out of luck in this regard if you live in the northeast states, Canada, Eastern or Northern Europe, or chillier parts of Asia. The only way you could grow them well is in a heated greenhouse.
Oca roots contain oxalic acid, which is also present in their cousin, wood sorrel (Oxalis acetosella). It’s also in leafy greens such as spinach and beet leaves. If you react badly to any of these plants, or you suffer from kidney issues or gout, then you might want to avoid oca tubers as well.
Harvesting and Preserving
Your oca tubers will be ready to harvest after the first frost has killed off the aerial parts. Once the foliage dies off and the stems start to wilt, it’s time to dig them up.
Oca is incredibly easy to store. Like potatoes, you can store them in sand or straw in a cold cellar and they’ll last for months. Alternatively, they’ll do just fine in a refrigerator. As long as they’re kept cool and dry, away from direct sunlight, you’ll be able to munch on them all winter long.
You can also preserve cooked oka the same way you would with potatoes. For example, if you made a soup or stew with them. Since they’re low-acid vegetables, you’ll need to pressure can them. Get yourself a great pressure canner and follow the directions on it that correspond with your elevation.
If you plan on growing oca again next season, be sure to replenish your soils deeply over the winter. It’s good to rotate your crops, so plan on where you’ll be cultivating them next. Then plant cover crops, and work in manure, bone meal, fish emulsion, whatever you can think of that will benefit these tubers.