Purple Shamrock (Oxalis triangularis)

The Purple Shamrock (Oxalis triangularis) does two things no other common houseplant does: it stops people in their tracks with deep violet, butterfly-shaped leaves, and it moves — folding its leaflets closed at dusk and reopening them at dawn in a daily rhythm called nyctinasty. It’s not a trick. It’s the plant responding to light, the same way it would in the understory forests of South America where it originates.

In spring and summer it also produces delicate blush-pink flowers on slender stems above the foliage. Fast-growing, easy to care for, and striking in any light — it’s one of the most rewarding plants you can keep on a windowsill.

Toxicity note: Mildly toxic to cats and dogs if ingested in large quantities (contains oxalic acid). Keep out of reach of pets that chew on plants.

What Makes This Plant Special

• Moves with the light: Leaves fold closed at dusk and reopen at dawn — a daily display that makes it feel alive in a way most plants don’t.
• Unmistakable color: Deep violet to burgundy-purple foliage that holds its color in a wide range of light conditions.
• Flowers too: Soft pink blooms appear in spring and summer, contrasting beautifully against the dark leaves.
• Fast grower: Visibly fills out week to week during the growing season.
• Goes dormant, then returns: May die back in winter — this is normal. Keep the bulbs dry and cool, and it will resprout in spring.

Ed’s Plant Profile

• Botanical Name: Oxalis triangularis
• Common Names: Purple Shamrock, False Shamrock, Lucky Shamrock, Love Plant
• Family: Oxalidaceae
• Native Range: Brazil, Bolivia, Argentina, Paraguay
• Growth Habit: Clumping, from underground corms; 6–12" tall
• Toxicity: Mildly toxic to cats and dogs — keep away from pets that chew plants

Care Guide

• Light: Bright indirect light brings out the deepest purple color. Tolerates morning sun well. Avoid harsh afternoon direct sun which can bleach the foliage. Can adapt to medium light but color will be less intense.
• Water: Keep soil evenly moist during active growth — allow the top 1" to dry before watering again. Reduce watering significantly in winter when the plant may go dormant.
• Soil: Well-draining, slightly acidic mix (pH 5.5–6.5). A standard potting mix with added perlite works well.
• Humidity: Average household humidity (40–60%) is sufficient. No misting needed.
• Temperature: 60–75°F. Protect from drafts and temperatures below 55°F.
• Fertilizer: Monthly with a balanced water-soluble fertilizer (10-10-10) in spring and summer. Stop feeding during dormancy.
• Propagation: Divide the corms (small bulb-like structures) at repotting. Offsets form readily and can be potted separately.
• Dormancy: May die back completely in winter — this is normal and not a sign of death. Stop watering, store the pot in a cool dry spot, and resume watering in late winter or early spring to trigger regrowth.
• Pests: Generally trouble-free. Monitor for aphids or spider mites and treat early with insecticidal soap.

Troubleshooting

• Leaves not opening during the day: Insufficient light. Move to a brighter spot — the plant needs good light to complete its daily open/close cycle.
• Fading purple color: Too much shade. More light = deeper, richer color.
• Yellowing leaves: Overwatering or the start of natural dormancy. Check soil moisture and the time of year.
• Plant dying back completely: Likely entering dormancy — normal in winter. Don’t discard the pot. Keep dry and cool, and it will return.
• Leggy, stretched stems: Needs more light. Move closer to a window.

More Resources

Read our complete Oxalis Care Guide for in-depth guidance on dormancy, propagation, and seasonal care. Also available: Oxalis triangularis ‘Gold’ if you prefer chartreuse-yellow foliage.