False Shamrock (Oxalis): Types, How to Grow and Plant Care

While oxalis can be regarded as invasive when grown outdoors, quite a few varieties make for beautiful houseplants. 

Oxalis plants are valued not only for their beautiful and unique foliage, but also the way the leaves react to light. When it gets bright enough, false shamrock, or oxalis, will open its leaves, closing them up again when it gets too dark.

Quite a few varieties also produce flowers, even when indoors, making them very attractive options when it comes to growing plants inside your home.

Fancy growing your own oxalis houseplants? Here’s everything you need to know.

At a Glance: What You Should Know About False Shamrock

False shamrock comes from the Oxalis genus, forming part of the Oxalidaceae plant family, which is made up of over 550 different species of plants, found nearly all over the world.

The common name for some of these plants in the genus, false shamrock, comes from the resemblance of the foliage to shamrock, the young three or four-leaved clover which is typically a symbol of Ireland and St. Patrick’s Day.

In the garden, oxalis plants are used to suppress weeds as ground cover, as well as their great ornamental value. False shamrocks produce a plethora of flowers, which offsets the foliage nicely, and they make great plants for hanging baskets and containers, too.

How to Recognize Oxalis

Oxalis grows as clump-forming perennials, with a plethora of triangular or oval leaves. Depending on the species, the foliage may be a vibrant green, a deep, dark purple, or a mixture of the two.

In colder climates, they can be grown as annuals, as some types are very sensitive to colder temperatures.

False shamrocks also produce petite white, yellow or pink flowers.

Growing Oxalis Plants

Sunlight and Position

Oxalis plants need bright but indirect sunlight indoors, somewhere away from drafts, radiators, or anything else that might upset an otherwise stable temperature.

You’ll need to keep it somewhere where the temperature does not drop lower than 60°F (15°C) during the day, or 55°F (13°C) during the night. Try not to let the temperature get above 75°F (24°C), otherwise the plant can suffer.

Avoid putting oxalis in a humid environment, as this can disrupt the flowering cycle.

As oxalis grows from bulbs, you will need to provide a well-draining soil mix to ensure there’s no risk of root rot. 

You’ll be able to buy oxalis both as bulbs and as a potted plant. In general, buying the bulbs tends to be cheaper, but you will need to plant them up in spring or fall, and supply your own pot and compost.

You can move your oxalis plant outdoors in the summer months if you like, but remember that you’ll need to take it back inside once the temperatures cool, as some types of oxalis won’t stand any frost.

If you want to grow oxalis outside, full sunlight or partial shade will do. In partial shade you may see fewer flowers, but the growth habit may be less vigorous, too. This is not a bad thing, as false shamrock grows very quickly.

It is worth noting that the brighter the light you have your oxalis growing in, the better the color will be on the plant’s foliage.

When to Water Oxalis

Oxalis, like all plants which grow from bulbs, are vulnerable to overwatering. Always check the soil before you water any oxalis kept as an indoor plant, and allow the top portion of the soil to dry out in between watering.

Depending on the environment you grow your oxalis in, the size of the pot, and how many bulbs you have, this may be as much as once a week, or much less. 

It’s worth noting that oxalis can go dormant in the winter months, in which case you’ll need to stop watering the plant until you see signs of new growth, to allow it to rest.

Should You Feed Oxalis?

If you’re growing oxalis indoors, the plant will benefit from some fertilizer during the spring and summer months. Use an all-purpose houseplant fertilizer, and feed every third watering or so.

When to Divide Oxalis

If your oxalis plant is getting too crowded, or you just want to make sure that it will continue to flower, it’s worth dividing the bulbs every few years.

The timing is important, too. To avoid shocking your oxalis, aim to divide it about two weeks after your plant goes dormant for the winter.

Remove the bulbs from the soil, and separate a few into a new pot, and plant all the bulbs back up as soon as you can. 

It’s worth mentioning that it will take some time for the new bulbs to produce foliage, and will do so slower than the original plant.

Problems to Watch Out For

The number one killer of false shamrocks when kept as indoor plants is root rot, so be careful not to overwater the oxalis plant. 

Aside from this, as oxalis has soft stems, it is vulnerable to pests such as mealybugs, scale, spider mites, and aphids. These insects will feed on the plant tissue, and left unchecked, can kill your oxalis.

If you do see an infestation, it’s best to act quickly. You can remove most of these insects by hand, treating affected areas with cotton buds and rubbing alcohol diluted with water.

More than likely, you’ll need to do this a few times until signs of the pests disappear.

Types of Oxalis You Can Grow As Houseplants

Oxalis adenophylla ‘Silver Shamrock’

Silver shamrock is known for its silvery green, heart-shaped foliage, and produces pink and white flowers. It will get to a maximum height of 10cm, spreading to about 20cm wide if the pot is big enough.

While oxalis is notorious for being invasive when placed in the garden, Oxalis adenophylla or the silver shamrock is much more mild-mannered, and doesn’t spread profusely like other types.

Oxalis deppei ‘Iron Cross’

If you can’t decide between purple or green shamrock, why not go for a variety that does both? The leaves of Oxalis deppei are almost heart-shaped, bright green at the ends, and deep purple at the heart of each leaf group.

If this wasn’t enough, this oxalis produces dark pink flowers in summer, contrasting these colors nicely.

Oxalis regnellii ‘Green Flowering Shamrock’

Also known as green wood sorrel, this particular variety has bright green, triangular leaves and produces dainty white flowers in summer, sometimes as soon as about eight weeks after you plant the bulbs. 

Oxalis triangularis ‘Purple Shamrock’

Perhaps the most popular type of oxalis, is the purple shamrock, grown both for its beautiful, two-toned purple foliage, and its dainty white flowers.

This particular variety has an interesting characteristic, where if the conditions become less than optimal, the foliage will die back, and the plant almost takes ‘refuge’ in the bulbs, until the conditions become more favorable, and you’ll soon see new shoots appear.

So if your plant does suddenly disappear beneath the soil line, don’t panic. Give it a few weeks, and you should see the foliage appear soon enough. It’s also a sign of dormancy, too.

Oxalis vulcanicola ‘Zinfandel’

If you’d prefer an oxalis plant with rounder foliage in the same dark tones, you can’t go wrong with ‘Zinfandel’. 

These very dark leaves are a beautiful show in their own right, but they really come into their own during summer, when the plant produces bright yellow flowers, making the perfect contrast between the two.

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