Oxalis Triangularis Care Guide (Purple Shamrock)

The Purple Shamrock’s unique and eye-catching foliage is sensational. Make sure the Purple Shamrock (Oxalis triangularis) gets a front and center location in your home where it can be admired. It’s not just the color and shape of the foliage that are spectacular; Purple Shamrock leaves open and close with the light, giving the appearance of a bunch of butterflies hovering around the plant.

Origin and History of Purple Shamrock Plants

The Purple Shamrock is native to countries in southern South America. It is also known as false shamrock and love plant. Oxalis triangularis is a recent invasive plant in Florida and Louisiana, where the temperatures accommodate outdoor growth. If you live in a warm state, please keep this plant inside so it doesn’t escape into the wild.

Purple Shamrock plants earn their common name from their triangle-shaped leaves growing in groups of three, like the original shamrock clover (Trifolium dubium). However, the Purple Shamrock is not related at all to the clover. In the United States, around St. Patrick’s Day, stores across the country market Oxalis triangularis as a “shamrock.”

The Purple Shamrock plant’s foliage is unrivaled in appearance and intrigue. Its leaves are deep purple or maroon and triangle-shaped. The leaves can also be green, variegated, or have a lighter reddish-purple tinge in the center of each triangle. Each grouping of three is actually one leaf, and the triangles are leaflets. They grow together at the end of a smooth, slender purple or green stem.

The Purple Shamrock plant grows 6-18 inches tall and 12-24 inches wide. Its stems spread outwards from the central root to create a bushy appearance, even though each stem and leaflet set is delicate and ethereal on its own. They look like miniature vibrantly-colored paper airplanes or butterflies clustered en masse around the plant.

The butterfly effect is further accentuated by the plant’s photonastic response – its leaves open during the day and close at night. Don’t be shocked when you see your plant moving! The flowers also close up at night and open during the day.

Oxalis triangularis flowers are small, white or pale pink, and trumpet-shaped. They appear on thin stems above the leaves during spring and summer. While the leaves are usually considered the main attraction, the sweet five-petaled flowers are also quite charming.

Oxalis Triangularis Dormancy

The Purple Shamrock is a bulb plant. Like most other bulbs, it requires a period of dormancy to stay strong. Dormancy allows the bulb to rest, renew, and store up nutrients to grow and bloom again.

In most cases, Oxalis triangularis will go dormant after the spring and summer flowering season. However, this may vary as the plant may choose a different time. Generally, young plants go dormant every year while mature plants will every 2-7 years. Don’t worry if you see the leaves stop opening. This is the beginning of dormancy.

Eventually, the foliage will wither and die off. Stop watering when you see this happen and don’t add any fertilizer. When the foliage is brown, remove it by cutting it back to the soil. Don’t cut off the foliage while it still has color – the bulbs are still gathering nutrients during this time, and removing the foliage too soon weakens them. Let the foliage get entirely brown.

Move the plant to a cool low-light location to fully rest for 4-6 weeks. Then, bring it back to a brighter location and wait for the next growth period. New growth will appear, but it may take a couple of weeks. Patience is the key; it’s worth it!

As soon as you see new growth, resume watering but just lightly at first. Then, transition it to the usual watering and feeding schedule. The new growth may be slow at first, producing only a few small leaves. Don’t worry; this is normal as it “wakes up.”

Oxalis Triangularis Care

In this section we cover important Oxalis triangularis care topics such as watering, lighting, fetrilization, repotting, and more:

Growth Habit

Purple Shamrocks are fast growers. And they live a long time. Oxalis triangularis plants are regularly passed from generation to generation.

The plants may go into dormancy every year, and during this time, the foliage is cut back to the soil. Mature plants usually don’t need their foliage cut back every year.

Light

Bright, indirect light is ideal. Don’t let direct sunlight touch the foliage as it will burn and die. A spot set back from a window is perfect. Or, use a sheer curtain or blinds to block the direct sun rays.

If the Purple Shamrock doesn’t receive enough light, its growth will slow, and the foliage will get very leggy. The legginess is due to the stems stretching out to find the light. If you see this happen, move the plant to a location with more light.

Water

Only water the Purple Shamrock plant when the top two inches of soil are dry. Since this is a bulb plant, it is crucial that it not be overwatered. Overwatering leads to bulb rot. Stick your finger in the soil every time before watering to check the moisture levels.

Remember not to water at all when the Purple Shamrock is in dormancy.

Temperature and Humidity

The best indoor temperature is between 60-70F. Anything over 80F may send the plant into dormancy since it doesn’t like heat. Even if it doesn’t go into dormancy, it may start to look withered and droopy in high temperatures. Also, any temperature below 55F may induce dormancy. The Purple Shamrock is a bit picky about climate.

Ensure your indoor Purple Shamrock is placed away from heating vents, wood stoves, drafts, and air conditioners, as all these will inhibit growth.

Average household humidity, between 30-60%, is fine.

Soil and Potting

A high-quality houseplant potting soil is fine. It should be well-draining to prevent the soil from getting too soggy and rotting the bulb. Only use pots with drainage holes so water can fully drain out of the bottom. Again, it is essential to ensure that the bulb isn’t constantly wet.

Fertilizer

Add fertilizer every 3-4 weeks during the growing season. Don’t add any fertilizer when the Purple Shamrock is in dormancy.

Pruning

Not much pruning is needed with the Purple Shamrock plant. Remove dead or dying foliage as you see it. And, when the plant enters dormancy, cut it back to the soil. Only cut it back after all the foliage has died, though.

Repotting

Repot Oxalis triangularis every 1-2 years. The best time to repot is when the plant is dormant. Repotting refreshes the nutrients in the soil, and it is essential to do this even if you’re not moving the plant to a larger pot. You can repot it to the same container to keep it the same size or move it to a pot one size bigger to encourage growth.

Toxicity

Oxalis triangularis is toxic to animals. Keep it up and away from cats and dogs. It is incredibly toxic to horses. The leaves and flowers are edible for humans, but they contain high amounts of oxalic acid, which should only be consumed in moderation.

Oxalis Triangularis Propagation

It’s best to propagate when the plant is dormant but not directly after entering dormancy. Wait two weeks after it starts dormancy to do any propagation. Purple Shamrock plants are propagated through corms, the name for their little bulb growths. Only propagate from fully mature and healthy plants.

1. Remove the Purple Shamrock plant from its pot.
2. Gently pull the bulbs apart. The bulbs look like little immature pinecones.
3. Fill a container with potting soil and water it well, so the soil is moist but not soggy.
4. Plant 1-5 bulbs in each container. They should be 1-2 inches apart. Planting the bulbs together creates a fuller mature display.
5. Cover the bulbs with 1-1.5 inches of soil.
6. Place the pot in a bright, warm location.
7. Keep the soil evenly moist during this time.
8. In 2-3 weeks, new growth will appear.

Pests & Disease

Here are a few common houseplant pests & diseases that you should look out for when keeping Oxalis triangularis:

Spider Mites, Whiteflies, Aphids, and Thrips

These pests are difficult to see until they become a real problem. The best treatment is prevention; regularly inspect the Purple Shamrock foliage, especially underneath the leaves.

If you notice brown spots, yellowing, or a plant struggling to thrive, you’ve likely got the beginning of an infestation. The tiny pests eat or suck the juices out of leaves and stems, causing initial harm and inviting other diseases to attack the damaged foliage.

A neem oil preparation applied to all the foliage every 5-7 days works well. To make a neem oil treatment, mix two teaspoons of neem oil and one teaspoon of dish soap in a quart spray bottle. Fill the rest of the bottle with water and shake well. Another good alternative for treating any of these pests is insecticidal soap.

Root Rot

Soggy, overwatered soil leads to bulb rot. The bulbs become so saturated that they can’t breathe and then get mushy and rotting. This is why well-draining soil and a container with drainage holes are essential. Signs of root rot include stunted or lacking growth and wilting foliage.

Common Questions about the Purple Shamrock Plant

Here are a few of the most common questions that we get about Oxalis triangularis care:

Why are the leaves on my Purple Shamrock turning yellow?

Yellow leaves are a sign of overwatering. Make sure you are checking the moisture level every time before watering. The top two inches of soil should be dry. If it’s not dry, wait a few more days to water.

What is causing the white spots on the leaves of my Purple Shamrock?

White spots are indications of powdery mildew or rust. These diseases tend to occur when the Purple Shamrock isn’t getting enough light, or the humidity is too high. First, treat the foliage with a neem oil solution to rid the plant of the diseases. Then, move the plant to a location with more light and less humidity.

How often do Oxalis triangularis corms (bulbs) multiply?

The corms multiply like crazy. They will likely double in a year or two if the plant is healthy. This means you can propagate many more plants and give them to all your friends and family. Oxalis triangularis is the houseplant that keeps on giving.

It’s not nighttime; why is the foliage on my Purple Shamrock closing up?

The leaves will close if overly disturbed or if the light is too harsh. If you notice your foliage is closing when it’s not nighttime, assess the conditions and make sure the light isn’t too intense. Also, try not to disturb the plant too much – it’s very sensitive.

All the foliage on my Purple Shamrock plant died; is my plant dead?

No. Most likely, the plant is entering dormancy. Please read the section above about dormancy and how it works with this houseplant. Young plants usually go into dormancy every year, but mature plants may only go dormant once every 2-7 years. A lot depends on the plant and its growing habitat. Do not throw the plant out!

Can I grow Purple Shamrock outdoors?

Yes, in USDA climate zones 6-10, Oxalis triangularis can be grown outdoors. Grow outside with caution, though, since it tends to spread and may escape into the wild. Keeping it in a planter is usually a good idea. It can also be an indoor/outdoor plant and move with the seasons.

There are few houseplants as visually and aesthetically stimulating as the Purple Shamrock plant. Between the rich mahogany-purple tri-fold leaves and daily movement, Oxalis triangularis appeals to the senses. Purple Shamrocks take indoor plants to another level. They aren’t difficult to care for, but make sure you follow the guide to ensure it thrives.