Oxalis

( OX - al - iss )

At-A-Glance Information

This genus of flowering perennials and annuals includes species which need light shade in warmer climates and regular water. These plants are commonly called Wood Sorrel, Yellow Sorrel, Pink Sorrel, False Shamrock, or Sourgrass. Leaves resemble those of Clover plants, and flowers can be pink, white, rose, or yellow. Use these plants to fill between stepping stones, add to containers or mixed beds, or as small-space groundcover plants. Take care when planting these in the garden, as all plant parts are mildly to moderately toxic to humans and pets if ingested.

Oxalis Species and Varietals

The genus Oxalis is a member of the plant family Oxalidaceae and includes 550 species. The genus name is derived from the Greek word 'oxys' which means sharp or sour, referring to the oxalic acid content of the plants which give them a sour flavor. The best growing zones for Oxalis vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Oxalis acetosella (Wood Sorrel, Shamrock, Stabwort, Alleluia, Fairy Bells, Irish Shamrock, Cuckoo Sorrel)
This species grows best in USDA hardiness zones 4-8 or Sunset growing zones 1-10 and 14-24; it is native to many northern temperate regions of the globe. It reaches 5 inches tall and spreads via rhizomes. Blooms appear in late springtime and are white with purple to pink veins. It can be somewhat aggressive in woodland areas.

Oxalis adenophylla (Silver Shamrock, Chilean Oxalis)
This species is best in zones 4-9 and 12-24, and is native to South America. It has a dense, compact habit reaching 4 inches tall and 6 inches wide. Each leaf has many grey-green leaflets. Flowers are lilac-pink and have deeper pink veins, blooming in late spring on 4-6 inch tall stems. These are great candidates for rock gardens and can also be grown in pots or in the ground. It needs great drainage, and should be planted in fall.

Oxalis alpina (Alpine Woodsorrel, Alpine Wood-Sorrel)
​These plants are native to North and Central America. The specific epithet alpinus refers to the species' habitat range in alpine environments. Individual plants reach up to 4-11 inches tall at maturity, and spread to form clumps. Green leaves are trifoliate and heart-shaped and flowers are pink, purple Alpine Woodsorrel grows well in USDA hardiness zones 6-9.

Oxalis articulata (Pink Sorrel, Pink Wood Sorrel, Windowbox Wood Sorrel, Chari Amilo, Sourgrass, Netho, Khatta, Saag, Pink Shamrock)
These perennial flowering plants are native to temperate regions of South America, and have been introduced to and naturalized in many other areas of the world. They are suited for USDA hardiness zones 7a-10b. They typically produce pink to violet flowers and reach 18 inches tall. This species is considered invasive in North America, Europe, Australia, and New Zealand.

Oxalis bowiei (Bowie's Wood Sorrel, Red-Flower Wood Sorrel, Cape Shamrock)
These plants are native to South Africa, and have naturalized in Australia. The species is named for Kew plant collector and botanist James Bowie, and produces flowering stems that exceed a foot in height. They produce cherry-pink flowers over a long season during the summer months and grow well in USDA hardiness zones 8-10. Bowie's Wood Sorrel is considered highly invasive in Australia, North America, Japan, and Europe.

Oxalis corniculata (Creeping Woodsorrel, Procumbent Yellow Sorrel, Sleeping Beauty, Creeping Lady's Sorrel, Sourgrass, Sour Clover)
These small, creeping plants grow well in moist climates in USDA hardiness zones 4-10, and are native to southeastern Asia. Leaves are green, turning maroon with exposure to sun. Flowers are small and yellow, closing when not in direct sun (hence the common name 'Sleeping Beauty'). Individual plants form mats of foliage to 2-8 inches tall and spread to form dense patches. Creeping Woodsorrel is considered invasive in Australia, Hawai'i, New Zealand, Asia, Canada, the United States, and regions of Central America.

Oxalis dillenii (Southern Wood-Sorrel, Slender Yellow Woodsorrel, Dillen's Oxalis, Dillen's Wood Sorrel)
This species is native to North America and is suited for USDA hardiness zones 5-11. Individual plants are low-growing and produce green foliage and tiny bright yellow flowers, reaching up to 4 to 16 inches tall when mature. Southern Yellow Wood Sorrel is considered invasive in Europe and Canada.

Oxalis grandis (Great Yellow Woodsorrel, Large Yellow Woodsorrel)
These annual plants are native to the eastern United States, and bloom from May through June. Flowers are yellow and foliage is green. Leaves are somewhat larger in this species than those of others in the genus. These plants prefer to grow in sandy woods and alluvial soils. Large Yellow Woodsorrel grows well in USDA hardiness zones 5-7.

Oxalis hedysaroides (Fire Fern, Red Oxalis, Red Malunggay, Velvet Oxalis, Trébol Morado, Acederilla, Red Flame)
These plants are native to Colombia and Ecuador, and produce golden-yellow flowers. Leaves turn dark purple to reddish with sun exposure and close up at night. These plants typically reach about 12 inches tall with a 4 inch spread, and have a trailing habit. Fire Fern is suited for growing in USDA hardiness zones 10 and 11.

Oxalis hirta (Hairy Sorrel, Tropical Woodsorrel, Hairy Oxalis, Trailing Oxalis)
This species of Oxalis grows best in USDA hardiness zones 8-11 or Sunset growing zones 8, 9 and 14-24, and is native to South Africa. Reaches a foot tall and a foot and a half wide. It has an upright, branching habit that droops somewhat under the weight of the foliage and flowers. Leaves are small and pale green, and flowers are pink, blooming in late fall and winter. Plant goes dormant in summer. This species is a great candidate for rock gardens. This species is considered invasive in Australia and California (United States).

Oxalis lasiandra (Palm Tree Oxalis, Mexican Shamrock)
This species is best in USDA hardiness zones 7a-10b or Sunset growing zones 8, 9, 12-24, H1 and H2 and is native to Mexico. This plant has a taproot and forms a clump of foliage that reaches 16 inches tall and wide. Plants produce reddish stems and green foliage. Flowers are dark red to pink-magenta and bloom from summer through fall.

Oxalis montana (Mountain Woodsorrel, Wood Shamrock, Sours, White Woodsorrel, Common Woodsorrel)
These plants are perennials and are native to North America's eastern regions. Foliage is green, and flowers are white with pink central bands. Plants typically reach about 4 inches tall at maturity and have a 6-inch wide spread. Mountain Woodsorrel is suited for growing in USDA hardiness zones 3-7.

Oxalis oregana (Redwood Sorrel, Oregon Oxalis)
This species grows well in USDA hardiness zones 7-9 and Sunset growing zones 4-9 and 14-24, and is native to the forests on the coasts of Washington, Oregon, and California. It reaches 10 inches tall and spreads by rhizomes. It blooms in spring and fall, with flowers in white or pink with lavender veining. It makes an attractive shady area groundcover and will choke out other plants nearby. It is considered somewhat invasive, especially in favorable conditions. It can tolerate wet conditions, but will die back in cooler temperatures.

Oxalis pes-caprae (African Wood-Sorrel, Bermuda Buttercup, Buttercup Oxalis, English Weed, Goat's-Foot, Soursob, Soursop, Suring, Hommayda)
These plants produce yellow flowers and green foliage and are suited for USDA hardiness zones 8-11. They can reach up to 6-12 inches tall with flower stems up to 18 inches in height and spread rapidly via underground bulbs to form large carpets. This species is considered a highly invasive noxious weed in Mediterranean climates worldwide, including California, Portugal, Spain, Italy, Australia, and the Middle East.

Oxalis purpurea (Oxalis variabilis) (Purple Woodsorrel)
This species is best in USDA hardiness zones 8-10 or Sunst growing zones 8, 9 and 12-24. It is native to South Africa, and reaches 4 inches tall and 6 inches wide. Leaves are dark green and flowers are rose-red, blooming in fall and winter. It spreads by both bulbs and rhizomatous roots but is not aggressive or considered invasive. Plant bulbs an inch deep and 3-5 inches apart. Cultivars include 'Grand Duchess' (with larger flowers in rose-pink, white and lavender), 'Garnet' (with magenta blooms), and 'Ruffles' (with white double flowers). This species is highly invasive in Australia and California (United States).

Oxalis stricta (Common Yellow Woodsorrel, Common Yellow Oxalis, Upright Yellow-Sorrel, Lemon Clover, Sourgrass, Juicy Fruit, Sheep Weed)
These plants are native to North America and east Asia. It has naturalized on most continents around the world. Flowers are yellow and foliage is green. Plants typically reach up to nine inches tall when mature and in bloom, though they can also be much shorter, depending on the climate. Common Yellow Woodsorrel thrives in USDA hardiness zones 3-11. This species is considered invasive in California (United States), Canada, Europe, and Asia.

​Oxalis spiralis (Spiral Sorrel, Spiral Woodsorrel, Volcanic Sorrel, Velvet Oxalis)
This sub-species grows best in USDA hardiness zones 9-11 or Sunset growing zones 8, 9 and 12-24, and its varieties are more well-known, and more widely grown, than the species. Cultivars include 'Aurea' (also called Golden Oxalis, with gold-yellow to copper foliage), 'Plum Crazy' (with dark plum-red leaves), 'Sunset Velvet' (with shifting foliage tones throughout the year), 'Zinfandel' (to 10 inches tall with black-purple foliage) and 'Molten Lava' (pictured, with green to orange leaves and yellow flowers).

Oxalis tetraphylla (Oxalis deppei) (Lucky Clover, Four-Leaf Sorrel, Four-Leaf Pink Sorrel, Iron Cross)
This species reaches 6-10 inches tall and forms a clump that spreads slowly by tubers. Leaves are medium green and are banded with purple at the base. Flowers are bright pink and bloom in spring through summer. This plant needs well draining soil and is great in containers. It grows best in USDA hardiness zones 7-10 or Sunset growing zones 7-9 and 12-24 and is native to Mexico.

Oxalis triangularis (Purple Shamrock, False Shamrock, Wood Sorrel, Love Plant, Butterfly Plant)
This species grows best in USDA hardiness zones 8-11 or Sunset growing zones 7-9 and 12-24 and is native to South America. It reaches 12 inches tall and 18-24 inches wide, and forms a mound of burgundy foliage. Flowers are light pink. Cultivars of this species include 'Atropurpurea' (pictured; with rich, deep burgundy foliage and light pink blooms), 'Mijke' (with lighter foliage and pink-purple flowers), 'Ebony Allure' (with purple-black leaves), and 'Charmed Wine' (larger than the species, with light pink flowers and dark plum foliage).

Oxalis tuberosa (Uqa, Oca, Yam, New Zealand Yam, Oca de Peru, South American Wood Sorrel)
These plants, native to the Andes, are crop competitors to the Potato. These plants are cultivated as crops in many areas of the world, including Bolivia, New Zealand, Peru, Venezuela, Colombia, France, and Mexico. Roots are harvested 150 to 210 days after sowing. Oca can be grown in USDA hardiness zones 6-9 

​Oxalis versicolor (Candy Cane Sorrel, Candy Cane Oxalis, Candy Cane)
​This species is best in USDA hardiness zones 7-10 or Sunset growing zones 6-9 and 14-24; it is native to South Africa. It reaches 3-6 inches tall (12 inches at the maximum) and 8 inches wide. Leaves are medium green, and flowers are white and funnel-shaped. Petals have crimson edges on their undersides, creating a candy cane pattern before they fully open.

Caring for Oxalis

Take care when planting these in the garden, as all plant parts are mildly to moderately toxic to humans and pets if ingested. Oxalis is typically grown from seed or purchased as corms or seedlings from reputable nurseries. Plant your Oxalis in a spot in the landscape that receives full sun. These plants ideally need between 6 and 8 hours of direct sun each day to grow well, but do appreciate some afternoon sun in warmer climates when temperatures are at their peak. Ensure that soil is well-draining, moderately fertile, and has a pH of between 6.0 and 6.5 (slightly acidic). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Lay down a 2-3 inch dressing of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and increase soil moisture retention.

Water newly planted Oxalis plants regularly to help them develop strong root systems. At maturity, these plants are drought-tolerant, able to get by on rainwater alone with some supplemental waterings in the warmest months of the year. Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prune in late summer or early fall when flowering is complete, removing dead, damaged, or diseased foliage. Deadhead spent flowers as they appear by removing the entire flowering stem to its base. These plants will need to be divided every few years, especially if they are grown in containers. For instructions on how to divide Oxalis plants, see the propagation section below. In especially cold weather areas, dig up the roots and store them in a cool, dark, dry place over the winter months. They can be replanted in springtime in the garden when temperatures rise again. In zones where Oxalis is perennial, they can survive in the landscape for decades before needing to be replaced. They spread over time, providing new plants indefinitely.

Caring for Oxalis Indoors
Oxalis, in addition to being a great ornamental for the landscape, also makes a handsome houseplant. Ensure that the pot you are growing Oxalis in has adequate drainage holes on the bottom to allow excess water to escape. When grown indoors, use a potting soil amended with sand or grit to increase drainage. Water newly planted Oxalis regularly to help them develop strong root systems. At maturity, these plants are drought-tolerant, able to get by with some supplemental waterings during the warmest months of the year. These plants will need to be divided every few years, especially if they are grown in containers. For instructions on how to divide Oxalis plants, see the propagation section below.

Harvesting Oxalis
Oxalis tuberosus, also called Oca, Uqa or Yam, produces underground storage tubers that are similar to potatoes. These tubers are edible, and are gaining popularity as an alternative to more traditional starches as they are low in carbohydrates and rich in Iron and vitamin C. Tubers are planted out in springtime in well-draining soil. Full sun is the best exposure for the largest tubers. Each plant can grow to be three feet in diameter, and produce up to 50 tubers, which have a lemony flavor (akin to that of Kohlrabi or cooked Turnips) but are otherwise used pretty similar to potatoes. Their flavor becomes sweeter when cooked, and the citrusy tang can disappear if they are boiled or steamed.

The best time of the year to harvest Oca is late fall or winter, before the first hard frost of the year comes around. A good rule of thumb is to harvest when the leaves start to die back. Working from the outside in (to avoid damaging the roots with your tools), lift the mass of tubers out of the ground. Brush off any dirt that remains as well as possible, and then rinse them off either outdoors or in the kitchen sink. They are eaten with the skin on, and are delicious when roasted and served with other veggies, added to stews or soups, or even consumed raw.

​Disclaimer: Information contained on this website is strictly and categorically intended as a reference to be used in conjunction with experts in your area. Foraging and consumption of plant parts should never begin without the guidance and approval of a local plant specialist. The providers of this website accept no liability for the use or misuse of information contained in this website.

Propagation

Oxalis can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Shamrock plant, follow the instructions below:

Propagating Oxalis by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
  2. Harvest your seeds. The seed pods on plants are pretty easy to spot, they're left behind after flowers have faded, and stand erect on stems. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Oxalis by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:
  1. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
  2. Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
  3. Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
  4. Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.
Oxalis plants produce ridged, green capsules that look like miniature Okra pods. They contain between 10 and 50 seeds each, and burst open when fully ripe.
Oxalis seeds are tiny, flattened, and reddish-brown to tan.

Problems and Pests

Certain species are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Oxalis plants can be susceptible to developing issues with the following pests and diseases in the landscape:
  • Aphids
  • Whiteflies
  • Spider Mites
  • Fungal Leaf Spot
  • Powdery Mildew
  • Rust
For more information on these pest and disease issues, consult the following pages:
​

Gallery

Oxalis can form a nice groundcover for filling in around larger plants like Yucca.
Purple Oxalis paired with variegated Brunneria.
A simple low bowl filled with white-flowering Oxalis is used as a centerpiece on this front porch.
Many gardeners know Oxalis as a weedy plant, but many species make great ornamentals.
This simple lawn border features Dusty Miller, burgundy Oxalis, Snapdragon, and Petunia.
Chilean Oxalis is grown for its unique grey-green foliage as well as its gorgeous pink blooms.

Videos

All about growing Oxalis as a houseplant.
Growing tips for Oxalis plants.
How to get rid of Oxalis weeds.
How to plant and grow Oxalis.
Oxalis tuberosa produces edible tubers that are intentionally cultivated. Learn more in this video.
How to grow and eat Oca.

Resources

How to Grow and Care for Oxalis
How to Grow New Zealand Yams
How to Grow and Care for Shamrock Plants (Oxalis)
How to Grow and Care for Oxalis
Wikipedia: Oxalis
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 467 - 468, Oxalis