Oxalis Hedysaroides Care – Fire Fern Oxalis Complete Care Guide

This is an ultimate guide on identifying, growing and caring oxalis hedysaroides or fire fern oxalis plants.

Oxalis Hedysaroides Care- Grow Fire Fern Oxalis Complete Guide

Oxalis plants are considered to be a weed in general. But, there are a lot of oxalis varieties that rival the beauty of even celebrated ornamental plants.

And, one such species is oxalis hedysaroides.

The yellow coloured flower in between crimson colored leaves is a treat to the eyes. Isn’t it?

Well, if you are planning to add this beauty to your plant collection, then you really this article.

I will cover all the important things you need to grow this plant in detail. The topic includes,

Without any more fluff, let’s get started.

What is Oxalis Hedysaroides?

Oxalis Hedysaroides is a crimson perennial plant that is also known as Oxalis Hedysaroides Rubra. It belongs to the Oxalidaceae family and the genus Oxalis, also known as wood sorrels or false shamrocks.

This is a family of over five hundred flowering plants, with the majority having palmately divided leaves with 3 to 10 leaflets.

Although Oxalis hedysaroides is its scientific name, the plant is commonly referred to as the Fire fern. It originated from the Caribbean region and is widely distributed globally except at the poles.

Despite the name, the fire fern oxalis, it is not a fern. This is because it’s a flowering plant, and true ferns do not flower nor produce seeds.

This delicate mounding plant makes a great addition to rock gardens and border edgings. It is also used as container accents to create visual contrasts.

The stunning crimson-colored leaves and bright yellow flowers have made it a popular potted plant on many window sills.

Oxalis Hedysaroides Appearance

Oxalis Hedysaroides is a deep crimson or purple plant with abundant bright yellow flowers. The plant can grow to a height of about 30 cm and has a spread that is 10cm wide. However, some plants may grow to a height of 100 cm and have a spread of 20 cm.

The plant has thin and wiry stems of a similar color to the leaves. Oxalis Hedysaroides start with green leaves, which turn purple or maroon from exposure to the sun.

During the day, the plant will rotate its leaves to follow the sun, and at dusk, the leaves will appear to quiver and close partially by folding them in half.

The evergreen oxalis plant flowers from June until November. The flower stalk extends from the top of the stem above the leaves to produce small bright yellow flowers around one centimeter in size.

Oxalis Hedysaroides Care

The oxalis hedysaroides is a light feeder and requires only moderate watering. It thrives in any area with partial to direct sunlight, while pests, weeds, and diseases are rare. Good care will give you years of healthy growth of your plants.

Care for your fire fern oxalis by following the guidelines below:

Oxalis Hedysaroides Soil Requirements

Oxalis hedysaroides require slightly sandy soils that drain well or moist soils without being waterlogged. The plant will rot in excessive water, while very dry soils won’t sustain it.

The fire fern oxalis does well in slightly acidic soils with a pH between 6.0 and 7.0. Therefore, you should use a potting medium that’s indicated for acid-loving plants.

You can also prepare the planting soil by mixing 4 parts of organic material like peat moss and one part of perlite. Put this mixture in a well-drained porous pot to prevent waterlogging.

You may also place this soil mixture in a flower bed or the garden, taking care to leave 12-inch spaces between each plant.

Adding a three-inch layer of well-aged manure or organic compost to the top 9 inches of soil in your garden will also work. Cuttings should be placed about an inch below the surface of the earth.

Light For Fire Fern Oxalis

Fire fern oxalis requires approximately 6 hours of sunlight, with afternoons in the shade during very hot summers. A mix of shade and partial sunlight works best for the plant, although it tolerates all-day exposure to sunlight pretty well as a tropical plant.

A brightly lit window sill which receives intermittent sunlight during the day will also work just fine. This is why most people prefer to place fire fern oxalis on their window sills. Indoor plants will drop leaves and become dormant if they do not receive sufficient sunlight.

Avoid placing your Oxalis under shaded trees or in areas that do not receive adequate sunlight when planting in the garden. Also, ensure the spacing is done right, so each plant spread doesn’t overlap with its neighbor.

Temperature & Humidity

Temperatures between 65-75ºF + (18-24ºC +) are advisable, with temperatures closer to 70ºFmost ideal for the plant. This means the plant will do well in gardens without many trees which obstruct the sun.

Humidity levels of 50% or higher are preferred, although the plant can tolerate lower levels without damage.

Watering Fire Fern Oxalis

Oxalis hedysaroides require moderating watering when the soil is slightly dry. The plant is drought tolerant, so do not over-water it. Water only if the soil is visibly dry.

If you are not certain, gently stick your finger to the ground, and if it feels moist, do not water. For potted plants, lift the pot and check underneath. If the bottom is damp, the plant needs to dry further before watering it again.

If you choose to drip irrigate, let the soil dry between watering intervals. Plants can also be completely dried out when dormant. Remember that soggy leaves and roots make the plant susceptible to fungus and diseases.

It’s best to water the plant in the morning, so it has time to dry out throughout the day. Generally, your plants will require watering every 1-2 weeks.

Fertilizing Oxalis Hedysaroides

Unlike most foliage plants, Oxalis hedysaroides is a light feeder and needs a balanced 20-20-20fertilizer or lower with micronutrients applied at 220ppm nitrogen. You may also use a blooming fertilizer such as 7-9-5.

However, wait for about two months after planting to start feeding your plant. Potting soils have enough nutrients when fresh so that the plant won’t need fertilizer for a while.

Remember that if your fire fern oxalis is not growing well, it will only respond to fertilizer if lack of nutrients is the cause. Lack of sunlight or poorly drained soils might also cause the problem, so don’t rush to fertilize your plants when you notice a problem.

Be careful not to apply excess nitrogen, as this will result in both root tip and leaf burn, especially if the soil is dry. Using ¼ tablespoon of fertilizer per gallon per month should be enough.

However, discontinue feeding during winter when growth slows down or if the plant is dormant to prevent damaging it with excessive nitrogen.

Best Place to Grow Fire Fern Oxalis

The Oxalis Rubra’s natural habitat is warm and humid climates with plenty of sunshine. For this reason, its natural habitat is the Caribbean, and the adjacent countries of Colombia, Venezuela, and Ecuador.

These regions correspond to the USDA Hardiness Zone 10, characterized by warm temperatures and high humidity. Zone 10 comprises two subsets, 10a, and 10b. Oxalis is preferable in 10b, with about 5 degrees warmer temperatures than 10a.

With minimum winter temperatures of between 30F and 40F, these regions are also conducive for winter gardening. Zone 10 areas include southern California, southern Florida, the equatorial regions of North America, and Hawaii.

Winter frost in this region occurs between the start of December to the end of January. This means you can plant your Oxalis Rubra as early as February once the frost has reliably passed and temperatures are warm enough to support growth.

Although Zone 10 is the ideal growth area, Fire fern oxalis will also do well in Zones 7 to 11, as long they get sufficient light, warmth, and humidity.

Potted Oxalis will have greater flexibility with climate, as you can shift the plants indoors during winter to shield them from the cold. Indoor temperatures should be above 60F.

Remember to take them outside for a full day of winter sunlight as well. During other seasons, ensure your window sill has temperatures of around 75F during the day and no less than 60F at night.

Pruning Oxalis Hedysaroides

Like any other plant, pruning your Oxalis Hedysaroides Rubra plant is an essential part of its care. The fire fern oxalis can have excessive unappealing growth with poor foliage if left to grow wild.

Pruning is, therefore, necessary to produce an abundance of foliage and flowers. If done right, the results can be spectacular. If done incorrectly, you may damage your plant irreversibly.

Luckily, pruning Oxalis is not a complicated affair. Because Oxalis is a flowering plant, pruning should start immediately as blooming begins in June. This will rejuvenate abundant flower growth for the season.

Also, make sure that you remove excess branches from each steam, paying attention to the plant’s symmetry. It’s important that your pruning serves to expose as many leaves as possible to sunlight. Therefore, prune stems with excessive branches and leaves.

Brown or yellowing leaves should be removed at any time of the year. This will encourage healthy leaves to sprout and discourage pests and fungal growth from your plants.

Pruning will ensure a balanced symmetry to your plant and ensure all leaves receive adequate sunlight.

Oxalis Hedysaroides Propagation

Propagating your plants allows you to easily expand your fire fern oxalis collection without the need to buy more plants. Although plants are cheap to buy, propagating them is even more affordable. You can share your oxalis hedysaroides with friends and family or plant more around your garden.

Fire fern oxalis can only be propagated through cuttings. However, some species of the oxalis genus have bulbs, while others, especially the invasive varieties, have seeds. However, the Oxalis hedysaroidesRubra does not.

To propagate your fire fern, you will need:

  • Mature plants for tip cuttings
  • Clean porous pots
  • A sterlized knife
  • Rooting powder, liquid, or gel
  • Fresh potting soil and water

Below is an easy step-by-step guide on how to propagate your fire fern oxalis.

Step 1

Prepare a porous pot with potting soil or by mixing 4 parts of peat moss with one part of perlite.

Step 2

Locate a healthy and mature plant. This will be your mother plant.

Step 3

On the mother oxalis hedysaroides plant, cut a non-flowering branch about 5 inches long.

Step 4

Dip the end of the cuttings into rooting hormone powder and gently shake off any excess powder.

Step 5

Use a finger to make a 2-inch-deep hole in the pot, and plant the cutting.

Step 6

Water the plant moderately, taking care not to waterlog it.

Step 7

Place the pot with the cutting where there is adequate sunlight.

It is advisable to propagate your plants in the spring or summer. This is because the cuttings will require good sunlight, humidity, and warm temperatures to thrive.

Remember that cuttings need more care and close attention than mature plants, so keep a close watch on them. If your cuttings do not grow, do not give up. Cuttings require patience, and you will master the propagation skills in no time.

Please note that rooting powder contains natural auxins, powerful plant hormones that should only be used for propagation. Applying it to a mature plant will kill the root system and damage the entire plant.

Oxalis hedysaroides rubra cuttings can still grow without rooting powder, so you can skip this if you prefer to let your plants grow naturally.

Oxalis Hedysaroides Toxicity

Oxalis hedysaroides is an oxalic-acid-containing plant and is therefore mildly toxic to humans and pets. 

It is rated by the California Poison Control System as a toxic species level 2B, or oxalates late-onset, meaning oxalis hedysaroides contains toxic oxalates but does not cause immediate problems.

You will have to ingest large quantities of the plant to experience any negative side effects. For this reason, toxicity in humans is unheard of. The name oxalis means ‘sour,’ and the plant has an acidic and sour taste, irritating cats and dogs.

Symptoms of oxalis hedysaroides poisoning include nausea, vomiting, diarrhoea, and loss of appetite. If swallowed, do not induce vomiting. Remove remains of the plants from the mouth and hands, wash with water, and call the poison center.

Do wait to get symptoms of oxalate poisoning, and carry a piece of the plant with you if you are advised to go to the hospital. This will help your doctor identify the exact species of plant for effective treatment.

If ingested by animals in large amounts, oxalic acid toxicity will cause drooling, staggering, and the formation of kidney stones. 

Call a vet to get medical advice if you suspect your pet has ingested oxalis hedysaroides.

Always keep all your houseplants away from young kids and pets for safety.

Common Problems of Oxalis Hedysaroides

Oxalis Hedysaroides is a hardy plant and has few problems. Weeds, pests, or diseases are rare, so you should find the plant very easy-going.

If grown in waterlogged soils, with little light or low temperatures, the plants can also get diseases. The following are common problems with fire fern oxalis and their solution:

Yellow leaves and mushy stems

These are a sign of root rot, which is caused by overwatering and poorly drained soils. The leaves will turn yellow and the stems mushy. Remove the plant from the pot, trim rotting roots and replant in fresh soil.

Root rot in oxalis hedysaroides can also be a result of a fungus. In this case, reversing the damage might be more difficult. It may be better to get rid of all diseased plants and start afresh.

In that case, clean and disinfect all your pots by scrubbing them with a brush and then soaking them in a mixture of 1 part household bleach and 9 parts of water. Let the pots sit in this mixture for about ten minutes.

You may also use vinegar to disinfect pots of your affected oxalis hedysaroides instead of bleach.

Brown and wilting leaves  

This is a sign of low humidity and underwatering. The leaves may also have crispy edges. Watering the plant and pruning dead leaves should revive the plant.

Spider Mites

Once they appear, spray with horticultural Neem oil and regularly wipe down the plant.


This can be an issue if the plant is close to other infected oxalis hedysaroides plants. Remove visible bugs, and wipe the plant with cotton wool dipped in rubbing alcohol at least twice a week until they disappear.

If caught late, mealybugs can damage your plant irrevocably, and you may need to throw out such plants and plant fresh ones.

Check other plants in your garden for mealybugs and remove them to prevent re-infestation.

Aphids and Whiteflies

These pests rarely attack your plants, but occasionally this might happen. Use horticultural oil or neem to remove these as well. Avoid using toxic pesticides because oxalis plants do not tolerate them very well.


Oxalis hedysaroides plants tend to drop leaves and go dormant if climatic conditions are not favorable. 

Just because your plant isn’t producing foliage doesn’t mean it’s dead. Add a little fertilizer, water the plant, and put it out under sunlight to stimulate growth.

If your oxalis hedysaroides plant goes dormant in the winter, stop watering and let the leaves brown. Remove all the leaves and place the pot in a cool dark area for about 1 month.

Fire fern oxalis requires a shorter dormancy period than other oxalis species, which can remain dormant for up to 3 months.

After this period of dormancy, return the oxalis hedysaroides plant to the window sill, resume watering and add a little fertilizer. Your plant should grow once again without a problem.

Similar Oxalis Varieties

Wrapping Up

Oxalis Hedysaroides are wonderful garden or potted plants for every home. 

With their crimson leaves and beautiful yellow flowers, these plants will add curb appeal to your lawn, add character to your garden, and brighten your interior spaces. 


To back up the information we provide in our articles, the Plantials team only uses high-quality sources published in peer-reviewed university or scientific research journals.

  1. Cultivating Oxalis Hedysaroides, Texas A&M University Libraries
  2. Pot Culture Of Oxalis Species, Food & Agriculture Organization Of The United Nations.
  3. Oxalis Species: In Vitro Culture, Micropropagation, And The Formation Of Anthocyanins, Biotechnology In Agriculture Journal.
  4. In Vitro Propagation And Culture Of Oxalis Hedysaroides H.B.K. Cv. Fire Tree, Food & Agriculture Organization Of The United Nations.

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