United States Edition

Oca   

Oxalis tuberosa

Oca is part of the Oxalis genus. Its scientific name is Oxalis tuberosa. The botanical name epithet for Oca (tuberosa) means 'tuberous'.

Oca is a perennial plant that is grown as an annual. This is the same situation as the potato. If you leave the tubers in the ground, they will regrow. Unfortunately, they will be too crowded and yields in subsequent years will be poor. Oca is best dug and replanted every year if the goal is to use it as a food plant.

There are many varieties of oca – at least 16 are available from sellers in North America. More varieties are available in the UK and Europe. Hundreds of varieties exist in the Andes, although there is now very little exchange of varieties between oca’s native countries and the rest of the world due to export restrictions.

Blooms appear in these approximate colours:   Yellow and   Red. When mature, blooms are roughly 1.5 cm (that's 0.58 inches in imperial) in diameter.The blooms display an average of 5 petals. It is a flowering edible vegetable that typically grows as an annual/perennial, which is defined as a plant that can matures and completes its lifecycle over the course of one year or more. Oca is known for growing to a height of approximately 1.62 feet (that's 50.0 cm in metric). This plant tends to bloom in late summer, followed by first harvests in early winter. This plant is a great attractor for bees, so if you are looking to attract wildlife Oca is a great choice. Consider White, Pink, Orange, Red and Sunset to grow as they are very popular with home gardeners.

Peru is believed to be where Oca originates from.

Oca needs a moderate amount of maintenance, so some level of previous experience comes in handy when growing this plant. Ensure that you are aware of the soil, sun, ph and water requirements for this plant and keep an eye out for pests.

This plant info is provided by the myfolia gardener's wiki. All details about Oca have been kindly provided by our members.

How to grow Oca

  • Partial Sun

    OR +
  • Full Sun

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  • Medium

The foliage of oca is known to fall over under its own weight in late July or early August; this is normal and is to be expected. The tubers do not begin to grow until the days get shorter in late September; so harvesting times (at least in the Northern hemisphere) are commonly late November to early December. The foliage of oca is killed by frost; however, the tubers continue to grow for a couple of weeks thereafter. It is therefore recommended to wait a couple of weeks after frost has killed the tops before harvesting, which is said to increase tuber yield greatly.

Some growers report good results from hilling up oca like potatoes. Others report damage to the plant from this practice. It seems more who report good results grow in mild climates. Yield does not appear to be greatly different in either case.

Try to plant in a location that enjoys partial sun / full sun and remember to water moderately. Use Zone 7 - Zone 9 as your guideline for the appropriate climate for this plant. Keep in mind when planting that Oca is thought of as tender, so it is imperative to wait until temperatures are mild before planting out of doors.

Growing Oca from seed

You can start from seeds or tubers. Tubers are the most common method of propagation. They will naturally begin to sprout over winter; if kept in the dark, you’ll end up with a mass of spindly sprouts that will break when separated. Therefore, check tubers regularly whilst in storage and, upon signs of sprouting, place in a cool, well-lit place to “chit”, in the same way as for seed potatoes.

Seeds are tiny and require light in order to germinate, so should be surface sown. They are better raised as transplants but can be started outdoors. Plants grown from seed will be unique, although they can be propagated indefinitely from tubers after the first generation.

Ensure a distance of 1.62 feet (50.0 cm) between seeds when sowing - look to sow at a depth of approximately 0.0 inches (0.0 cm). Soil temperature should be kept higher than 15°C / 59°F to ensure good germination.

By our calculations*, you should look at sowing Oca about 60 days after your last frost date .

Transplanting Oca

There seems to be general concensus among growers that oca tubers are best planted indoors in mid-March, and then planted out, in full sun, after the last frost.

Seedlings are somewhat fragile and are best transplanted after they have reached 5-8cm. It can take 60 days or more to get them to this size; performance of seedlings is quite variable.

Ensure that temperatures are mild (minimum night temperatures should be around 5°C / 41°F) and all chance of frost has passed before planting out, as Oca is a tender plant.

By our calculations*, you should look at planting out Oca about 0 days after your last frost date.

Harvesting Oca

Harvest is best delayed as long as possible. If you have a truly frost-free climate, plants will generally die in March. In most climates, frost will kill the plant before that. Tubers continue to increase in size for two to three weeks following frost-kill of the top growth, so you should account for that when harvesting. Frozen soil will kill the tubers, so if you expect a hard freeze to any significant depth, it is best to dig the tubers even if you would normally wait longer.

Varieties have different rates of maturity and frost tolerance.

Seed Saving Oca

Oca has a tristylous system of incompatibility. Each flower has its filaments and styles arranged in three tiers; one tier is styles and the other two are filaments. Flowers are classified as long-styled, mid-styled, and short-styled depending on whether the styles are in the top, middle, or bottom tier. You must have varieties of at least two of these flower types in order to have a good chance of producing seed.

Oca seems to set seed under mild and moist conditions. High humidity, night temperatures of 10-15 degrees C and daytime temperatures not exceeding 20 degrees C appear to be ideal. Under such conditions, oca may flower from June until the frost (northern hemisphere). Under less than ideal conditions, oca may refuse to flower until fall, or fail to flower at all.

Companion plants for Oca

These plants have been known to grow well alongside Oca so consider planting:

Many plants that complete their growth by late summer are good companions for oca, since it does not begin to put on rapid growth until later in the season. Bush peas seem like a particularly good match. Other growers have found success with tomatoes and peppers.

Repellent plants for Oca

These plants will not grow well with Oca so avoid planting these within close proximity:

Planting with other tuber and root crops is generally not a good idea, since oca’s late maturity would conflict with timely harvest.

Common Oca problems

These problems, diseases and pests are known to affect Oca plants:

Oca appears to have few problems with disease in ideal climates. In warm climates, it may suffer from stem rot.

Oca is very pest resistant. Deer and rabbits tend to sample it, but rarely eat much if other options are available. Slugs and snails leave it alone. Ducks will eat the foliage to the ground. Burrowing rodents may cause problems around harvest time.

Other names for Oca

Oka, Oxalis Yam, New Zealand Yam

Oxalis crenata

Oca care instructions

How long does Oca take to grow?

These estimates for how long Oca takes to sprout, grow and harvest are from real observations from real gardeners, right around the world. Start logging and journaling your observations to participate!

When should I plant Oca?

Our when to plant Oca estimates are relative to your last frost date. Enter your frost dates and we'll calculate your sowing and planting dates for you!

Footnotes

Oca Forums

  • Oca Growers

    This group is for those who grow (or wish to grow) Oca (Oxalis tuberosa), a South American tuber which seems to be ga...

    13 members / 7 topics
  • Shamrock (Oxalis) Growers

    This group is dedicated to the discussion of growing Shamrocks (Oxalis). This group is intended for all varieties of ...

    4 members / 3 topics

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