This diverse genus is comprised of hundreds of species. There's a wide range of annuals, perennials, and even tropical types of oxalis. Many oxalis are bulb-forming plants while others form vigorous spreading plants that can create dense colonies. Several species can also make wonderful, easy-to-grow houseplants.
While many species of oxalis have beautiful blossoms, these plants are most commonly grown for their foliage. You can often find them in your local florist's shop around St. Patrick's Day as their leaves closely resemble shamrocks and they are often regarded as a sign of luck. These geometric-shape leaves, often triangular in shape, come in shades of purple, burgundy, pink, green, and silvery gray.
The plants bloom with small five-petal blossoms that have intricate details on the inner petals. These blossoms often begin as tubular flowers that twist open to show off dainty stripes and dark-color throats. They can be found in shades of pink and white, while other species feature yellow and orange blossoms. There are even species like Oxalis versicolor that have flowers that resemble peppermint candy: mostly white with an edge of red on the backside that creates a swirled look as the petals twist open.
Oxalis Care Must-Knows
Growing conditions can be quite different between the numerous species in this genus. One of the best bets to find out how to care for your oxalis is to research its origin for information on its natural habitat. Then you can learn its proper growing conditions. Many species of oxalis tend to be alpine plants and therefore need well-drained soil and will not tolerate any amount of standing moisture. These are also typically cool-growing plants and do not care for warm summer weather and may even have a summer dormancy period. Many other species are woodland plants which prefer more shaded garden settings and are generally more tolerant of typical garden conditions. There are also tropical species that are not hardy and are accustomed to warmer climates and will fare better in the summer months.
Related: Annual Care Guide
In general, oxalis are fairly versatile in their sun requirements. Sun exposure varies depending on your species. Many of the bulbous types of oxalis require a period of dormancy. The time of year they become dormant varies from species to species. During this period of dormancy it is important to withhold water to encourage dormancy and prevent the bulbs from rotting. This dormant period is also the best time to divide plants.
More Varieties of Oxalis
Oxalis tetraphylla 'Iron Cross' offers leaves divided into four leaflets. The center of each is decorated with a purple blotch that looks great against the pink flowers. It grows 10 inches tall and wide. Zones 8-9, though it also thrives as a houseplant.
This variety produces stunning orange-chartreuse foliage and decorative golden-yellow flowers all spring and summer. It grows 10 inches tall and wide. Zones 9-11, or try it as a houseplant.
Oxalis regnellii var. triangularis bears rich burgundy-purple foliage and pink-blushed white flowers. It grows 12 inches tall and 8 inches wide. Zones 7-10, though it's also a good variety to grow indoors.
This cultivar is native to areas of the Pacific Northwest and bears white or pink flowers in spring and summer over silver-splashed foliage. This groundcover grows 8 inches tall. Zones 7-9
Oxalis adenophylla is an easy-growing groundcover with silvery-blue foliage and pink flowers in late spring. It grows 5 inches tall and 6 inches wide. Zones 6-8