Commonly called clover, the three-petaled, pinwheel-shaped oxalis appeals as both a ground cover and an indoor plant. Oxalis resembles the yellow-flowered clover that was most likely used by Saint Patrick to describe the trinity, bringing Christianity to Ireland. Often sold in stores around St. Patrick's Day, oxalis is as an easy-to-grow substitute to the original.
Oxalidaceae, the family known as wood sorrel, hails from Africa and has between 800 and 850 different species. Foliage colors vary from green to purple or maroon, while blooms can be pink, burgundy, white or yellow. Species with yellow flowers resembling buttercup are the weedy varieties found growing naturally. Cultivated varieties provide rich purple and deep green shades of foliage, with large triangular-shaped tri-set leaves and a range of pretty blooms.
Wild oxalis species are commonly found growing prolifically in the southern United States, where it is known as creeping wood sorrel or southern yellow wood sorrel. Found from Florida to North Dakota, this natural form will grow and spread without care.
Oxalis stricts and Oxalis corniculata are the weedy varieties with yellow flowers that bunch together to make lush ground cover. Oxalis aceosella and Oxalis purpurea have shades of green triangular- or diamond-shaped leaves with pink or white flowers, depending on the cultivar. Oxalis regnellii has deep-purple leaves and white flowers. The good luck oxalis, O. deppei, is commonly taken for a clover, and O. rubra sports pretty pink blooms.
The oxalis grows on a rhizome and should be considered a bulb for planting purposes. This root structure will slowly spread, making it perfect to fill in rock garden spaces. In garden beds, oxalis prefers sun to light shade but may look better planted next to a brighter-colored plant. Plant in well drained, moist soil.
Oxalis needs continuous moisture but should not be allow to get soggy. Place in bright light but not direct sun. Fertilize lightly every two to three weeks during growth phase. Prune dead foliage and spent blooms regularly. Since a rhizome behaves like a bulb, the oxalis may begin to wilt and yellow at the end of a flowering period. Place it in a dark, cool area, and don't water until new shoots emerge.