PlantWhy

Purple Shamrock (Oxalis)

Oxalis triangularis · Houseplant

Quick answer: Water: When the surface is dry; little in dormancy. Light: Bright, indirect light; good light brings more flowers. Soil: Loamy, well-drained potting mix. Pets: The ASPCA lists shamrock plants (Oxalis species) as toxic to cats and dogs because they contain soluble oxalates. Listed signs include drooling and tremors; kidney failure is rare in cats and dogs. Keep it out of reach, and if your pet chews it, ask your vet.

A houseplant with deep purple, triangular leaflets that fold down at night and small pale flowers. It grows from small rhizomes and takes regular rests: when leaves fade, it is usually going dormant, not dying.

Purple Shamrock (Oxalis)
Photo: KENPEI, CC BY-SA 3.0 · Wikimedia Commons
💧WaterWhen the surface is dry; little in dormancy
☀️LightBright, indirect light
🐾PetsToxic to pets

Care at a glance

Light
Bright, indirect light; good light brings more flowers
Water
Keep slightly moist; let the surface dry between waterings; very little while dormant
Soil
Loamy, well-drained potting mix
Temperature
About 60 °F nights and 70 °F days; outdoors only in USDA zones 8–11
Pot size
A snug pot; it does well slightly pot-bound, 6 in is typical (estimated)
Pot
Drainage holes; roots are shallow, so a wide, shallow pot works
Growth
6–18 in tall, 1–2 ft wide; rests for 1–3 months
Lifespan
Perennial; many years from rhizomes (estimated)

When?

It grows indoors all year but rests now and then, often after summer heat or as days shorten in autumn. Repot or divide just as new shoots appear after a rest (estimated).

Step by step

  1. Place it in bright, indirect light, such as near an east window.
  2. Water when the surface of the mix is dry; keep it slightly moist, never soggy.
  3. Feed lightly during active growth; follow the product label.
  4. When leaves yellow and collapse, cut them off: the plant is going dormant.
  5. During dormancy keep the pot dark, cool and nearly dry for 1–3 months.
  6. When new shoots appear, move it back to bright light and water lightly at first.
  7. Divide crowded rhizomes at the start of new growth to make more plants.

Common problems

Leaves yellow and die back all at onceUsually dormancy; stop watering, rest it, and wait for new shoots.
Long, floppy stemsToo little light; move to a brighter spot.
Soft, rotting baseOverwatering or a pot without drainage; let it dry and repot in fresh mix.
Pale speckling and fine webbingSpider mites; wipe or rinse the leaves and raise humidity.

Pets

The ASPCA lists shamrock plants (Oxalis species) as toxic to cats and dogs because they contain soluble oxalates. Listed signs include drooling and tremors; kidney failure is rare in cats and dogs. Keep it out of reach, and if your pet chews it, ask your vet.

Related tools

Soil and mulch calculator

Similar plants

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Sources

This page is general guidance; no pesticide doses are given.