House & Home / Houseplants

Oxalis Triangularis: The Last Growing Guide You’ll Need for Purple Shamrock

Oxalis triangularis: the last growing guide you'll need for purple shamrock

Looking for a colorful houseplant to add to your collection? You’ll love Oxalis triangularis, better known as the false shamrock. Its deep purple, butterfly-like foliage makes the perfect addition to any bright windowsill!

Keep reading for everything you need to know about Oxalis triangularis care and growing this charming houseplant indoors.

Common name(s)False shamrock, purple shamrock, love plant
Scientific nameOxalis triangularis
FamilyOxalidaceae (wood sorrels)
Height & spreadUp to 12 inches tall and 24 inches wide
LightBright indirect
Soil typeMoisture-retaining but well-draining
WaterLet first 1 to 2 inches of soil dry out
Disclosure: All products on this page are independently selected. If you buy from one of my links, I may earn a commission.
A mature Oxalis triangularis (purple shamrock) houseplant in an elevated pot displayed next to windows in a house

About Oxalis triangularis

Natural habitat

The purple shamrock houseplant is naturally found in much of South America, from Brazil down to the northern parts of Argentina. In Brazil at least, it grows in rocky zones by streams and rivers, although it has no problem spreading to areas marked by human activity. 

Because Oxalis triangularis is pretty hardy, it’s unsurprising that it has popped up as a naturalized species in various areas. It’s found in a bunch of states in the US (a 2021 report noted it in Arkansas, and it has also been found in Louisiana and Florida), as well as India.

Description

Oxalis triangularis was first scientifically described in 1825 by French botanist Augustin Saint-Hilaire. Although it’s often called a shamrock (which refers to the clover family), that’s not actually what it is.

Instead, Oxalis is a rhizomatous wood sorrel, which grows clusters of leaves from small, pinecone-like corms. This naming confusion has earned it the common name of “false shamrock.” 

The false shamrock is appreciated among houseplant enthusiasts for its trifoliate (three-petaled leaves), which are nyctinastic: They move according to the time of day. When it’s light out, the leaves will open, whereas at night they close up—similar to how prayer plants like Calathea makoyana, Maranta leuconeura, and Stromanthe sanguinea fold up their leaves at night.

False shamrocks are almost like butterflies with their shape and fluttering movements! Small, white to pink flowers add to the species’ whimsical charm.

It’s important to remember that Oxalis triangularis can go dormant, which is characteristic of bulb plants. Younger plants especially may die off yearly. They normally produce foliage and bloom for around half of the year, during the spring, summer, and early fall.

Did you know? You may find Oxalis plants labeled as Oxalis regnelli. This is the exact same species; the name is an accepted synonym. ‘Regnelli’ is sometimes used to refer specifically to the green version of the plant, but that’s not actually accurate.

Uses and cultural significance

While most people think of purple shamrocks when it comes to Oxalis triangularis houseplants, green varieties are commonly sold around St. Patrick’s Day because they look so much like the classic shamrock. If you’re looking for one, be sure to check out nurseries and garden centers around this time!

Like many of its other wood sorrel cousins (including True French sorrel and red-veined sorrel, which are more commonly grown in vegetable gardens), the false shamrock is noted as being edible. It’s high in oxalic acid, which means you shouldn’t overdo it, but this is what lends a lemony flavor to the leaves and flowers. The corms are also edible, being pleasant and sweet.

Another potential use of Oxalis triangularis is as a natural (food) coloring, something a few studies have explored. Apparently, the pigments (Anthocyanins) can be isolated and used for their attractive purple color.

Reddish-purple Oxalis triangularis houseplant in a white pot against a white wall dappled with sunlight

Oxalis triangularis varieties

Ever since this species became popular as both a houseplant and garden plant, nurseries seem to have been busy creating plenty of cultivars. There are loads of different Oxalis triangularis varieties out there! 

Here are the ones I could find, although I’m sure there are more out there:

  • Oxalis triangularis sp. Papilionacea: It isn’t always made clear whether this is a subspecies or a scientific synonym, but from my research, I’d say it’s the former. This variety has much larger leaves and also tends to grow taller.
  • Oxalis triangularis ‘Mijke’: Reddish-purple leaves and white flowers.
  • Oxalis triangularis ‘Atropurpurea’: Almost blackish-purple leaves with lighter purple centers.
  • Oxalis triangularis ‘Ebony Allure’: Fully purple-black foliage.
  • Oxalis triangularis ‘Fanny’: Fully green leaves and white blooms.
  • Oxalis triangularis ‘Sanne’: Leaves are green on top but purple on the bottom. 
  • Oxalis triangularis ‘Marmer’: Green leaves with lighter, silvery-green centers.
  • Oxalis triangularis ‘Amber’: Fully green leaves with pale pink flowers.
  • Oxalis triangularis ‘Irish Mist’: Dark and silvery green speckled foliage and white blooms.
  • Oxalis triangularis ‘Birgit’: Green leaves and very pale pink blooms.
  • Oxalis triangularis ‘Sunny’: Dark purple leaves with a hint of lighter purple in the center.
  • Oxalis triangularis ‘Burgundy Wine’: Dark burgundy foliage mottled with slightly lighter coloring.
  • Oxalis triangularis ‘Black Velvet’: Almost black foliage.

Where to buy Oxalis triangularis plants:

Close-up of flowers on Oxalis triangularis (false shamrock) plant

Caring for Oxalis triangularis

Light and temperature

If you’d like to grow an Oxalis triangularis plant in your home, be sure to place it in a bright spot. False shamrocks that don’t receive enough light can grow leggy and lose their charm, so go for a window that gets plenty of bright indirect light. A little sun won’t be a problem either, though don’t blast the plant without acclimating it first.

In terms of temperature, it can be a little difficult to find the right balance for your Oxalis, especially during the summer months. It has evolved to go dormant if things get too hot, meaning these plants can die off temporarily if your home gets too warm or if yours is close to a heating unit.

Room temperature is fine, although temps down to 55°F shouldn’t be too much of a problem either. If it’s consistently over 75°F, you might find your false shamrock dropping leaves and going into dormancy.

Water and humidity

Watering is another part of Oxalis triangularis care that some houseplant enthusiasts find a little difficult to balance. As I mentioned earlier, this is a rhizomatous plant, and its corms can be sensitive to rot caused by standing water.

On the other hand, if you let things get too dry, you risk your false shamrock thinking the hot and dry season has started and dropping its leaves for a dormancy period. Still, it’s usually better to underwater a little than to overwater it.

During the summer months, you can let the first inch or two of the soil dry out before watering again. In winter, when houseplants don’t need as much water, wait until the soil is about halfway dry. Remember that good drainage is just as important as proper watering habits! 

In terms of humidity, this isn’t an overly demanding species. Unless your home is exceedingly dry, you shouldn’t have any trouble in this department.

Soil and planting

Good drainage is essential for rhizomatous plants, because standing water can cause rot to set in on their corms and gradually kill the entire plant.

Luckily it’s not difficult to put together a soil that works well for your Oxalis triangularis: combining a lightweight houseplant potting soil with some perlite for added drainage usually does the trick.

When it comes to planters for false shamrock, some houseplant enthusiasts prefer a hanging pot, but a normal one is also totally fine.

The most important thing is that the planter should always have a hole in the bottom to allow excess water to drain easily. Terracotta planters, which are porous, work well if you tend to overwater. Otherwise, any regular plastic nursery planter with a decorative overpot is perfect.

Recommended products for Oxalis triangularis plant care:

Fertilizing

An active Oxalis triangularis can grow pretty quickly during the summer months when there’s lots of light available. If yours is putting out new leaves on a regular basis, it’ll probably appreciate a little extra fertilizer. You can use a diluted regular houseplant fertilizer on a biweekly basis.

Don’t use plant food if your false shamrock isn’t actively growing, especially if it’s dormant (when all foliage is gone). Excess unused fertilizer can damage the corms and roots.

Recommended fertilizers for Oxalis triangularis:

Pruning

Your false shamrock plant won’t need any pruning, though if it drops leaves, you can remove them. You’ll be doing so regularly if yours is transitioning into dormancy. 

Dividing or repotting

This is not a houseplant that requires frequent repotting, although it does appreciate some fresh soil on a yearly basis. You can keep it in the same planter until the rhizomes grow too large, at which point you can opt to either divide or repot.

Repotting will get you a larger and larger plant over time, which can be quite a sight to see when an Oxalis triangularis is in full growing mode and very bushy. On the other hand, dividing the corms is an easy way to produce more plants for your own collection or to give away.

Hand holding a small potted Oxalis triangularis purple shamrock plant against a white wall

Propagating Oxalis triangularis

It’s not difficult at all to propagate your false shamrock plant; as I mentioned above, you can do so through division. Individual leaves do root, but they don’t regrow unless any of the plant’s base is included. The best time to propagate is when your Oxalis is dormant but you’re ready to wake it up (usually around springtime).

Dig out the corms and see what you’ve got to work with. There will usually be more than one, which means there’s no need to break them apart. If you do need to separate bulbs, it’s usually easy enough to do so wherever offsets have begun to appear.

Pot the corms up separately and wake up the plant by providing plenty of light and regular small waterings. Voilà, now you’ve got multiple pots of Oxalis triangularis!

Small Oxalis triangularis plant in a purple ceramic pot on a wooden surface

Common questions about Oxalis triangularis care

Sources
Pazmiño-Durán, E. A., Giusti, M. M., Wrolstad, R. E., & Glória, M. B. A. (2001). Anthocyanins from Oxalis triangularis as potential food colorants. Food Chemistry, 75(2), 211-216.
De Saint, A. F. C. P. (1829). Flora brasiliae meridionalis (Vol. 2). apud A. Belin.
SERVISS, B. E., HARDAGE, J. W., & PECK, J. H. OXALIS TRIANGULARIS (OXALIDACEAE) NATURALIZED IN THE ARKANSAS FLORA.

About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring—all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »

No Comments

    Leave a Reply

    This site uses Akismet to reduce spam. Learn how your comment data is processed.