Oca
Oxalis Tuberosa
Oxalis tuberosa, commonly known as Oca or New Zealand Yam, is a unique tuberous plant valued for its edible tubers. Native to the Andes, it thrives in well-drained soil and full sun, making it a favorite among gardeners seeking to grow unusual vegetables.
Everything it needs
9 essentials at a glance
Watering
Oxalis tuberosa prefers consistently moist soil but should not be waterlogged.
Water every 1-2 weeks, allowing the top inch of soil to dry out between waterings. In the growing season, increase frequency if the soil dries out quickly. Signs of over-watering include yellowing leaves and root rot, while under-watering can cause wilting and leaf drop.
Light
Oca thrives in full sun to partial shade, ideally receiving 6-8 hours of sunlight daily.
It can tolerate some shade, especially in hotter climates, but too little light may hinder tuber development. Ensure it is placed in a location where it can receive bright, indirect light during peak hours.
Soil
The ideal soil for Oxalis tuberosa is well-draining, rich in organic matter, with a pH range of 5.5 to 7.0.
A potting mix that includes peat moss, compost, and perlite or sand will provide good drainage and aeration, essential for healthy tuber growth.
Humidity
Oca prefers moderate humidity levels around 40-60%.
To increase humidity, consider using a pebble tray with water or a humidifier. Signs of low humidity include browning leaf tips and increased pest activity, while excessive humidity can lead to mold growth.
Temperature
Oxalis tuberosa thrives in temperatures between 60-75°F (15-24°C) and is hardy in USDA zones 9-11.
It can tolerate brief periods of cooler temperatures but should be protected from frost, as it is sensitive to cold.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10 during the growing season, applying every 4-6 weeks.
Reduce fertilization in the dormant season. Signs of nutrient deficiency include stunted growth, yellowing leaves, and poor tuber development.
Pruning
Pruning is minimal for Oxalis tuberosa.
Remove any dead or yellowing leaves to promote air circulation and prevent disease. If the plant becomes leggy, you can trim back stems to encourage bushier growth. Deadheading is not necessary as it primarily grows for its tubers.
Repotting
Repotting is usually needed every 2-3 years or when the plant becomes root-bound.
Signs include roots growing out of the drainage holes or stunted growth. Choose a pot 1-2 inches larger in diameter and refresh the soil. Carefully remove the plant, loosen the roots, and place it in the new pot with fresh soil.
Propagation
Propagation can be achieved through tuber division or offsets.
In spring, carefully dig up mature tubers and separate them, ensuring each piece has at least one eye. Replant them in well-prepared soil, spacing them about 12 inches apart. Tubers can also be grown from seeds, but this method is less common.
When it's unhappy
Yellowing leaves
Why it happens
Over-watering or nutrient deficiency.
How to fix it
Check soil moisture levels and adjust watering frequency. Fertilize with a balanced fertilizer if nutrient deficiency is suspected.
Wilting
Why it happens
Under-watering or extreme heat.
How to fix it
Increase watering frequency and ensure the plant is not exposed to excessive heat. Move to a shadier location if necessary.
Root rot
Why it happens
Poor drainage or over-watering.
How to fix it
Allow the soil to dry out and improve drainage. If severe, remove affected tubers and replant in fresh, dry soil.
Pest infestations (aphids, spider mites)
Why it happens
Dry conditions or overcrowding.
How to fix it
Increase humidity and space plants adequately. Treat infestations with insecticidal soap or neem oil.
Leggy growth
Why it happens
Insufficient light.
How to fix it
Move the plant to a brighter location with more direct sunlight to encourage bushier growth.
Care through the year
Spring
In spring, prepare the soil for planting by adding compost and ensuring good drainage. Begin watering regularly as new growth emerges.
Summer
During summer, maintain consistent moisture and provide full sun exposure. Fertilize every 4-6 weeks to support active growth.
Fall
In fall, reduce watering as the plant begins to enter dormancy. Harvest tubers after the foliage dies back, usually in late fall.
Winter
In winter, keep the plant in a cool, dry place if dormant. Water sparingly to prevent rot, and avoid fertilizing until spring.
Toxicity & Safety
Oxalis tuberosa is generally considered non-toxic to pets and children. However, excessive consumption may lead to digestive upset due to oxalic acid content. Symptoms of ingestion include nausea, vomiting, and abdominal pain.
Good to know
How often should I water my Oxalis tuberosa?
Water Oxalis tuberosa every 1-2 weeks, allowing the top inch of soil to dry out between waterings. Adjust frequency based on temperature and humidity.
What type of soil is best for Oca?
Oca thrives in well-draining soil rich in organic matter, with a pH of 5.5 to 7.0. A mix of peat moss, compost, and perlite is ideal.
Why are my Oca leaves turning yellow?
Yellowing leaves can indicate over-watering or nutrient deficiency. Check soil moisture and consider fertilizing if necessary.
Can I grow Oxalis tuberosa indoors?
Yes, Oca can be grown indoors as long as it receives adequate sunlight. A south-facing window is ideal for optimal growth.
When is the best time to harvest Oca tubers?
Harvest Oca tubers in late fall after the foliage has died back. This usually occurs about 4-6 months after planting.
What pests should I watch for on my Oxalis tuberosa?
Common pests include aphids and spider mites. Regularly inspect your plant and treat infestations promptly with insecticidal soap.
How do I propagate Oxalis tuberosa?
You can propagate Oca by dividing mature tubers in spring or growing from seeds, though tuber division is the more common method.
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