Oxalis triangularis
Oxalis triangularisUSDA | Grow Zone
9-11Outdoors all year in zones 9 to 11. Anywhere colder, keep it as a houseplant. Protect it below 50°F.
- Light
- Bright, indirect
- Water
- When top 1 in is dry
- Humidity
- 50-70%
- Temperature
- 60-75°F (15-24°C)
- Difficulty
- Beginner
- Growth
- Moderate
- Mature size
- 12-18 in tall, wide
- Pets
- Mildly toxic to pets
Oxalis triangularis, also known as the purple shamrock, is a striking plant known for its unique triangular leaves that fold at night. Native to South America, it is cherished for its ornamental beauty and ease of care, making it a favorite among houseplant enthusiasts.
Ask Vesper about Oxalis triangularis
Ideal temperature
60-75°F is where it grows fastest. Below 50°F cold damage starts.
Spacing and harvest
- Mature size
- 12-18 in tall, wide
- Plant apart
- 12-18 in
- Frost
- Half hardy: light frost only
Everything it needs
9 essentials at a glance
Watering
Oxalis triangularis prefers to be watered thoroughly, allowing the top inch of soil to dry out between waterings.
During the growing season (spring and summer), water every 1-2 weeks, adjusting frequency based on humidity and temperature. In fall and winter, reduce watering to every 2-4 weeks. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause leaf curling and wilting.
Light
This plant thrives in bright, indirect light but can tolerate partial shade.
Ideally, it should receive about 4-6 hours of light daily. Direct sunlight can scorch the leaves, so placing it near a window with filtered light is best.
Soil
Oxalis triangularis prefers a well-draining potting mix, ideally a blend of potting soil, perlite, and sand.
A pH range of 6.0 to 7.0 is optimal. Ensure that the pot has drainage holes to prevent waterlogging, which can lead to root rot.
Humidity
This plant enjoys moderate to high humidity levels, ideally around 50-70%.
To increase humidity, consider misting the leaves, using a pebble tray with water, or placing a humidifier nearby. Signs of low humidity stress include browning leaf tips and curling leaves.
Temperature
Oxalis triangularis thrives in temperatures between 60-75°F (15-24°C).
It is hardy in USDA zones 9-11. Protect it from extreme cold, as temperatures below 50°F (10°C) can cause damage.
Fertilizing
Use a balanced, water-soluble fertilizer with an NPK ratio of 10-10-10 every 4-6 weeks during the growing season.
Reduce or stop fertilizing in fall and winter. Signs of nutrient deficiency include pale leaves and stunted growth.
Pruning
Pruning is generally not necessary, but you can remove any dead or yellowing leaves to encourage new growth.
Use clean, sharp scissors or pruning shears. Deadheading is not applicable as this plant does not produce significant flowers.
Repotting
Repot Oxalis triangularis every 1-2 years or when it becomes root-bound.
Choose a pot that is 1-2 inches larger in diameter. Signs it needs repotting include roots growing out of the drainage holes and stunted growth. To repot, gently remove the plant from its current pot, loosen any tightly bound roots, and place it in fresh potting mix.
Propagation
Propagation can be achieved through bulb division or offsets.
The best time to propagate is in spring. Carefully remove the bulbs from the soil, separate the offsets, and replant them in well-draining soil. Water lightly until new growth appears.
When it's unhappy
Yellow leaves
Why it happens
Over-watering or insufficient light.
How to fix it
Adjust watering frequency and ensure the plant receives adequate light.
Wilting leaves
Why it happens
Under-watering or low humidity.
How to fix it
Increase watering frequency and humidity levels.
Browning leaf tips
Why it happens
Low humidity or over-fertilization.
How to fix it
Increase humidity and reduce fertilizer application.
Root rot
Why it happens
Excessive moisture in the soil.
How to fix it
Allow the soil to dry out and ensure proper drainage; consider repotting if necessary.
Pest infestations (e.g., aphids)
Why it happens
Poor air circulation or high humidity.
How to fix it
Increase air circulation and treat with insecticidal soap or neem oil.
Care through the year
Spring
In spring, resume regular watering and fertilizing as the plant begins to grow actively. Ensure it receives plenty of bright, indirect light.
Summer
During summer, maintain consistent watering and humidity levels. Monitor for pests, as they can thrive in warmer conditions.
Fall
In fall, gradually reduce watering as the plant enters dormancy. Stop fertilizing and allow the plant to rest.
Winter
In winter, water sparingly and keep the plant in a cool, bright location. Avoid over-watering to prevent root rot during dormancy.
Toxicity & Safety
Oxalis triangularis is mildly toxic to pets and children. The leaves and bulbs contain oxalic acid, which can cause symptoms such as nausea, vomiting, and abdominal pain if ingested in large quantities.
Good to know
Why are my Oxalis triangularis leaves turning yellow?
Yellow leaves can indicate over-watering or insufficient light. Ensure you are allowing the soil to dry out between waterings and that the plant is receiving adequate indirect light.
How often should I water my Oxalis triangularis?
Water your Oxalis triangularis every 1-2 weeks during the growing season, allowing the top inch of soil to dry out. In fall and winter, reduce watering to every 2-4 weeks.
What type of soil is best for Oxalis triangularis?
A well-draining potting mix is ideal for Oxalis triangularis. A blend of potting soil, perlite, and sand with a pH of 6.0 to 7.0 works best.
How can I increase humidity for my Oxalis triangularis?
You can increase humidity by misting the leaves, using a pebble tray with water, or placing a humidifier nearby. Aim for humidity levels around 50-70%.
When should I repot my Oxalis triangularis?
Repot your Oxalis triangularis every 1-2 years or when it becomes root-bound. Look for roots growing out of the drainage holes as a sign it needs repotting.
Is Oxalis triangularis toxic to pets?
Yes, Oxalis triangularis is mildly toxic to pets and children. The leaves and bulbs contain oxalic acid, which can cause nausea and vomiting if ingested.
What is the ideal temperature for Oxalis triangularis?
Oxalis triangularis thrives in temperatures between 60-75°F (15-24°C). Protect it from temperatures below 50°F (10°C) to prevent damage.
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