Oxalis is a large genus of about 500 species of annuals and perennials, mainly from southern Africa and South America. They are grown for their shamrock-shaped foliage and their 5-petaled flowers that are cup- or bowl-shaped and open only in sunshine. Oxalis are good for naturalizing, for growing in a rock garden, trough, or raised bed, or as houseplants. Some species are very invasive.
Noteworthy CharacteristicsClover-shaped foliage. Pretty 5-petaled flowers that look like closed umbrellas when in bud.
CareIndoors, Oxalis need gritty soil and bright filtered light and low humidity. Water moderately and fertilize monthly while in growth. Keep barely moist when dormant. Outdoors, grow hardy woodland species in moist, fertile, humus-rich soil in full or partial shade. Other hardy Oxalis species need full sun and well-drained, organic soil of moderate fertility.
PropagationSow seed at 55° to 64°F in late winter or early spring. Divide in spring. Small pieces of rhizomatous species root readily with bottom heat.
ProblemsRust, seed smut, powdery mildew, and fungal leaf spots are common, while leaf miners and spider mites sometimes occur.