There are several plants in the Oxalis genus, many of which have been grown as food crops for generations. Rather than focusing on the species grown specifically for food (looking at you, Rumex acetosa!), this article is about common wood sorrel (Oxalis stricta).
It’s a beautiful, multi-purpose plant that can be used as an attractive groundcover, ornamental, replenishing cover crop, and/or a food source.
All About Oxalis
You’ve undoubtedly encountered oxalis or wood sorrel countless times and didn’t even realize it. Wood sorrel is often mistaken for clover (Trifolium spp.), and one of its colloquial names is actually “false shamrock.”
Both plants have three leaflets (although clover can occasionally have a lucky four instead), but whereas clover leaves are oval, oxalis leaves are noticeably heart-shaped.
This wild wood sorrel is a herbaceous perennial and grows enthusiastically in sandy, loamy, slightly alkaline soil. You can find it in sunny spots around woodlands and meadows all over North America and it also grows sparsely in Britain, Northern and Eastern Europe, and parts of northern Asia.
It flowers between May and September, erupting in tiny little yellow blooms that open during the day and close up and droop during the night, a process known as nyctinasty.
Oxalis re-seeds itself around any area where it’s planted, but also reproduces via rhizomes and stolons. This can make it quite invasive and difficult to get rid of, so make sure you’d like to have it around for a long time before you consider planting it!
Planting and Propagation
Whether you’re establishing your Oxalis via seeds, bulbs, or rhizome cuttings, aim for a late summer/early autumn planting. To plant the seeds, rake the area well, broadcast the seed in wide sweeps, cover lightly with soil, and water in. As for bulbs and rhizomes, plant them several inches apart, cover well, and mulch on top.
The root systems should establish themselves the following season and will come up and start spreading within a year or two. Remember that with perennials, the rule is “sleep, creep, leap.
The first year is dedicated to root establishment, the second will be sparse green growth, and the third will explode into verdant splendor (sleep, creep, leap).
Alternatively, you could plant your oxalis in springtime if you start seedlings indoors. Start seeds eight to 10 weeks in advance, and transplant the seedlings outside after your area’s last frost date.
If you find that your wood sorrel isn’t spreading in all the right areas, you can give it some extra help. Plant additional seeds in those spots, or divide the root rhizomes in September and plant them in places that you feel are sparse.
Caring for Oxalis
Test your soil first to ensure it’s hospitable to this plant’s needs, and amend accordingly if it isn’t. Aim for a soil pH between 4.0-7.0, with plenty of sand and loam. These plants don’t like to get wet feet, so ensuring proper drainage is critical.
These plants can thrive in full sun right through to partial shade, so they can adapt to most areas you may have on your property.
You’ll be delighted to know that these plants basically take care of themselves and thrive on neglect. Since they do best in poor, disturbed soils, you don’t ever have to offer them any fertilizer. In fact, feeding them can be detrimental to their well-being.
As for watering, remember that they don’t like to have wet feet at all. In fact, they do remarkably well in dry conditions. You’ll only need to water them if your area experiences an intense drought.
As mentioned above, few herbivores feed on Oxalis plants because of the toxic oxalic acid in their leaves. This doesn’t dissuade all other species, however, and there are several insect species that may damage your crop.
In particular, wood sorrel aphids (Abstrusomyzus reticulatus) and mangold aphids (Rhopalosiphoninus staphyleae) can wreak a fair bit of havoc, as can various grasshoppers. Certain moth larvae can also devour Oxalis leaves. Wedgeling moths (Galgula partita) lay eggs on the undersides of wood sorrel leaves, and when the caterpillars hatch, they munch their way through all the tasty, lemony greenery they can find.
Oxalis can also fall prey to whiteflies and various mites. Keep an eye on your plants, and if you find that they’re being damaged, hose them down with neem oil or garlic spray. That should fend off the interlopers and keep the plants in good health.
Use as Groundcover or Ornamental
Wood sorrel makes an attractive groundcover thanks to its vibrant green leaves and friendly, tiny blossoms. The leaves are also incredibly soft to the touch, and are far more pleasurable to walk or sprawl on than grass.
Additionally, it’s excellent as groundcover if your soil is quite depleted and inhospitable to plants that require more nutrients. Consider interplanting with creeping thyme for a beautiful, low-maintenance yard with the added benefit of repelling mosquitoes and other unwanted insects.
You can also grow wood sorrel as an ornamental, especially if you don’t have much time to dedicate to plant maintenance. It looks absolutely gorgeous in ceramic or stone planters, or spilling out over halved whisky barrels.
Benefits As a Cover Crop
Since wood sorrel thrives in depleted, disturbed soil, it can be excellent as a green manure to help replenish an area. Its rhizomes can help to break up clay and compacted earth, while the aerial parts that die off every winter decompose and add to the soil layer.
If you’re aiming to replenish an area, consider a green manure that incorporates oxalis but isn’t solely comprised of it. For example, a mix of wood sorrel, red clover, vetch, winter rye, and barley will add a wide variety of nutrients while also fixing nitrogen.
Oxalis as a Food Source
Wood sorrel has a bright, acidic, astringent flavor reminiscent of lemon. While this may sound rather exquisite, please note that these plants contain high levels of oxalic acid, which can cause kidney damage if eaten in large quantities.
You can use the little leaves as a garnish or toss a handful into a salad to add bursts of tartness here and there. I like to chop them and add them to potato salad along with chive flowers, and their lemony flavor also works well in soups and sauces.
This plant is high in vitamin C and has been used in tea form to help fight off summer colds. In the past, people ate it to treat scurvy, especially after long sea voyages, or as a replenishing springtime potherb.
Many folks survived on dried foods all winter long, so the vitamins C and A in these plants did them a world of good when they were available again.
Note that wood sorrel isn’t solely beneficial to humans as a food source: these plants feed numerous species year-round. Although herbivorous mammals generally avoid their leaves, the seeds feed sparrows, juncos, buntings, larks, finches, and small fuzzies such as mice and shrews.
It isn’t just the seeds that nourish our wild cousins: numerous insects love Oxalis pollen and nectar and can often be found flitting around patches. You may find cabbage white butterflies on your wood sorrel plants, as well as various bees, flies, and moths.
Note: never feed sorrel leaves to rabbits or equine species. It can kill rabbit companions, and cause severe colic in horses, mules, and donkeys.
Although we’re focusing on common wood sorrel (Oxalis stricta) here, there are lots of beautiful and interesting species worth growing.
Oxalis species are very far-reaching and can be found on almost every continent. Their uses are similar, though some have greater toxicity levels than others. As a result, it’s essential to identify your local species if you plan on eating them.
- Oxalis acetosella grows primarily across Europe.
- Oxalis montana is an Appalachian species with pink and white blossoms.
- Oxalis triangularis grows primarily in South America, and has deep purple leaves.
- Oxalis caerulea thrives in the American Southwest.
- Oxalis suksdorfii is found on the west coast from Washington to California.
- Oxalis oregana, aka “redwood sorrel,” is only found in BC, Washington, and Oregon.
- Oxalis melanosticta is native to the Cape Provinces of South Africa.
- Oxalis latifolia can be found in Mexico, South America, and parts of Australia.
- Oxalis griffithii grows abundantly throughout Asia, from Bhutan and Nepal to China, India, the Philippines, Korea, and Japan.
- Oxalis corniculata (shown above) thrives throughout southern China and Southeast Asia.
As you can see, Oxalis is a beautiful, versatile plant that can benefit any area. Do some research to see which species thrives best in your area, and consider adding some around your property!
Wood sorrel makes a lovely edging plant around walkways and along driveways and can also thrive around various tree species. However you cultivate it, enjoy its delicate prettiness, and sneak a leaf to chew on now and again.