Oxalis Triangularis in 6″ Pot

A clump-forming, herbaceous perennial from a tuberous rhizome (often called “corms” in cultivation). Height 15–30 cm (6–12 in), spread 30–60 cm (12–24 in). No aerial stem; long, delicate petioles (15–25 cm) rise directly from the base, each topped with a trifoliate leaf. Leaflets are sessile, obtriangular to obovate-triangular, 2–7 cm across, glabrous, and in the purple form a deep burgundy-maroon (wild type is green). The three leaflets look like butterfly wings or shamrock leaves; they exhibit nyctinasty—folding down at night, during disturbance, and in harsh light, and opening wide in morning light. In summer to autumn, slender stems carry umbels of 2–5 small funnel-shaped flowers, white to pale pink-lavender, 5-petaled, about 2–3 cm across; they also close at night. The plant is deciduous and has a natural winter dormancy: foliage collapses and dies back, then resprouts from the underground rhizomes in spring.

Quick care: bright indirect light to some gentle morning sun (east/west window). Purple pigment is strongest in good light; too little light causes greenish or leggy growth; harsh midday sun scorches leaves. Warm 15–24 °C (60–75 °F) during growth; can tolerate down to 10 °C (50 °F) but goes semi-dormant below ∼15 °C (59 °F). Soil: loose, well-drained, humus-rich (potting mix 60% + perlite 20% + leaf mold/cocopeat 20%); pH 6.0–7.5. Water when the top 2–3 cm dry—keep evenly moist in spring–summer, never soggy; reduce and then stop as foliage dies back in autumn. During dormancy (4–8 weeks in winter) keep the pot almost dry in a cool (13–16 °C), dim spot. Resume light watering when new shoots appear. Feed every 3–4 weeks in active growth with a balanced or high-potassium liquid fertilizer at half strength; none during dormancy. Propagate by dividing the scaly rhizomes/corms in late winter/early spring (plant 1–2 cm deep). Repot every 1–2 years. Watch for spider mites and aphids; overwatering causes rot. Toxic if ingested in quantity (oxalates)—keep away from pets/children (can cause stomach upset). Great for pots, hanging baskets, borders in mild climates (USDA 8–11); edible in tiny amounts but not recommended for regular consumption.