Oxalis triangularis

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Contents

1. Top Tips
2. Location, Water, Humidity & Fertilisation
3. Dormancy Care & Annual Flowers
4. Common Issues
5. Origins, Temperature, Propagation, Repotting & Toxicity.

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Top Tips & Info

• Care Difficulty - Very Easy
• Provide a bright location with an hour of either morning or evening sunlight throughout the year. Settings that boast overhead lighting are at an advantage for better 360º growth due to enhanced phototropism.
• Irrigate once the top third of the soil dries out, reducing this further in the autumn and winter months. Prevent droughts of any length throughout the growing periods.
• Provide a humid location by introducing a humidity/pebble tray to keep the surrounding moisture high during the winter. The use of artificial humidity isn't needed in the summer.
• Fertilise using a 'Houseplant' labelled feed every four waters in the spring and summer, reducing this to every six in the colder months.
• Regularly check for pests, most notably Spider Mites that'll locate themselves under the leaves.
• Provide a resting period over the autumn and winter months by reducing the amount of irrigation and temperature. Successful dormancy periods will reward you with lush new growth and possible flowers in the spring or summer months.
• Does your Oxalis need a pick-me-up? Why not buy our top-selling Soil Mix to give your green friend a new lease of life? We have sold over 3,200 batches in the last year alone, so click here to find out more...

Location & Light - 🔸🔸🔸

Although a bright indirect location is great, a few hours of morning or evening sun is excellent to maintain quality growth. Never situate an Oxalis in a dark location with minimal light, as root rot and elongated phototropism will quickly take over. In terms of the ideal location around the home, a few metres within a north, east or west-facing window, or in a semi-shaded conservatory are best. Provide a sun-filled location with a few hours of morning or evening sun to counteract the darker days and longer nights.

Water - 🔸🔸

Oxalis are straightforward to cultivate, as long as you water them when they need it. During the growing period, keep the soil relatively moist, never allowing persistent droughts to take over. During the autumn and winter months, water liberally (i.e. loosely, but not too infrequent) and avoid over-watering during its dormancy period. The plant will need a few months to rest after the fierce growing period, so overloading it with soggy soil will result in root rot. Under-watering symptoms include stunted or unreliable growth and leaf loss; these issues are usually due to either too much heat/sunlight, being potbound, transplant shock (similar symptoms to under-watering) or forgetfulness. Alternatively, over-watering symptoms include rapidly yellowing leaves, zero growth and plant death; avoid water-logging and persistent soggy soil to eliminate the chance of disease. Always keep in mind that Oxalis are in fact alpines, whereby they thrive in bright, dry-ish locations with good air circulation.

Humidity - 🔸🔸

Introduce a humidity tray whilst the heaters are operating to provide and maintain a stable level of humidity around the plant. Dry air will cause nothing but grief in the likes of brown leaf tips and poor health over this delicate time. 

Fertilisation - 🔸🔸

Supplement every four waters during the growing period, reducing this to every six in the autumn and winter. Never use a 'ready to pour' fertiliser into the soil without saturating the soil beforehand as it'll burn the roots. It's recommended to use 'Houseplant' feed as it provides the best blend of essential nutrients for quality growth; however, 'General-Plant' food at half recommended strength will do fine, too. Prolong the flowering period by opting for a potassium-based feed during the blooming process; tomato feed or 'Miracle-Gro' are the two to look out for.

A close up of the species' foliage.

Dormancy Care & Annual Flowers

Established specimens (2yrs +) will easily bloom during late spring if its previous dormancy period has been served well in the winter. As ukhouseplants been challenged many times on this subject, we've created an acronym to help you through this process - SHORT. The combination of drying soil, cooler temperatures and dark nights will contribute to better flowers in the following season, along with a much needed rest. 

The following steps must be taken from autumn to winter, to provide the best possible dormancy period.

Sunlight

Provide a bright location with a splash of winter sun. Darker settings will significantly reduce the chance of flowers once the spring returns. 

Hydration

Reduce waters so that the soil's majority becomes dry for the prevention of root rot and replication its dormancy period.

Occasional Feeds

One or two feeds using a 'Houseplant' fertiliser is all that is needed for supplementation, as too nutritious soil may hinder the chance of blooms later next year.

Reduce Everything

This one is a reminder to reduce everything - especially the temperature.

Temperature

This is the most significant step; reduce the temperature down by around 5℃ compared to the summertime or place in a room that's around 15℃ (59℉). The drop in temperature should ideally last until the inflorescence finishes blooming, although it can still be transferred into the main house as long as it sits on a pebble tray. You'll be at a significant disadvantage if the ambient temperature is kept constant throughout the year, as Oxalis will only respond with flowers in cooled environments. Never exceed the minimum temperature as it could lead to plant death or yellowed foliage at a bare minimum.

A Hard-Prune

N.B. - This step only needs to be performed every few years.

If the foliage begins to decline from late autumn, you may want to think about undergoing a hard-prune. This is where all of the foliage is cut back just above the soil line, to promote a better quality of leaves in the spring. Not only will it reward you with a fresh batch of purpleness, but it'll also eliminate any pests (for example Spider Mite) that fester in the cubbyholes of the prior foliage. Have a peak at the last image below, to get a grasp of what a bare Oxalis tuber looks like. Cut the leaves' petioles around an inch from the tuber and then remove them by hand once they brown over. 

This is also the perfect time to separate the clump of tubers into their own pots. Not only will the chance of transplant shock be at its lowest, but you also won't run the risk of damaging its delicate leaves. Scroll down to 'Propagation' for more info!

Situate the potted tuber in a cool, bright location with nighttime temperatures of 15℃ (59°F). Keep the soil on the dry side to life, allowing it to half-dry out in between waters. New foliage will develop in early spring, signalling the start of the new growing season. If yours begin to produce flowers and no foliage, keep pricking the flower stalks off to preserve its energy for the new leaves.

The flower of its close relative, Oxalis regnellii. 

Common Issues with Oxalis

Over-watering is the biggest killer amongst Oxalis. They mustn't endure extended periods of soggy soil, or water-logging as both will quickly lead to tuber/root rot. If you're worried about over-watering, provide a bright, warm location that offers an hour or two of off-peak direct sunlight to dry out the soil quicker. Vertically stab the soil using a chopstick twice a year in several places to improve oxygen-flow around the roots, but be sure to refill the holes before another water.

When an Oxalis is severely dehydrated, most of its leaves will crisp-up and fall off - leaving you with a bare pot. Although it may spell the end of juvenile plantlets, there may still be light at the end of the tunnel for more established specimens. If its tubers are still plump without any signs of retraction, prune-away any seriously affected leaves and contain the plant (with its pot) in a transparent bag. Keep the soil continually moist, providing a good level of indirect light and temperatures above 15°C  (59°F). Remove the bag every few days for around an hour to allow a fresh batch of air to circulate the tubers and soil. After a few weeks, new life will form in the nodal junctions on the tips, signalling the start of its recovery process. Maintain a sealed environment for the following fortnight until you feel it's necessary to release it back into the open air. For the prevention of environmental shock, be sure to introduce a humidity tray for higher levels of atmospheric moisture around the plant. Not only will this ease the specimen back into normal functioning life, but it'll also reduce the rate of transpiration (water-loss in the leaves), and therefore downplay the risk of dehydration and further decline.

Mould developing on the soil means two things - too little light and over-watering. Despite the harmlessness of the mould, it'll prove unsightly to most gardeners and is therefore removed once known. To remove, replace the top two inches of the soil for a fresh batch of houseplant compost. Either increase the amount of light received (no direct sunlight for the first few weeks to prevent environmental shock) or decrease the frequency of waters slightly. If the mould is accompanied by yellowing lower leaves, you may also have a case of root rot.

If your Oxalis develops flowers instead of foliage as it emerges from the dormancy period - prick them off. Allowing your specimen to produce lots of flowers with no foliage will zap it of energy, leaving you with a smaller-foliaged plant in the coming months. Like the image above, keep its leaves attached to the plant to help it gain more energy from photosynthesis. 

Due to the Oxalis’ sensitivity to chemicals, Leaf Shine shouldn't be used to improve the appearance of the foliage, and instead should be cleaned using warm soapy water. Failure to do so may cause yellowed, mottled spots that cannot be undone.

Spider Mites are small, near-transparent critters, that'll slowly suck out the chlorophyll out of the leaves. Have a check under the leaves, most notably along the midrib, for small webs and gritty yellow bumps. Click here to read our article about the eradicating Spider Mites, along with some extra tips that you may not find elsewhere!

Too low humidity can cause browning leaf tips with yellow halos. Although this won't kill your specimen, you may want to increase the local moisture to prevent the new growth from adopting these symptoms. Mist or rinse the foliage from time to time and create a humidity tray whilst the heaters are active to create a stable environment for your specimen.

Stunted or slowed growth during spring or summer can usually be blamed on too much sunlight or not enough water, but will commonly go hand in hand. Persistent droughts will cause yellowing leaves, stunted growth and foliage decline. If the soil is constantly dry and it doesn't receive direct sunlight, it may just be pot bound. Click on this link for more information about how to perform the perfect transplantation.

Pink, green or reddish leaves are normal behaviour for Oxalis. Both at the start and end of the leaf's cycle, it should adopt a pink or reddish tone to it; simply remove the dying leaf to improve the growing conditions and overall appearance of the plant.

A steady decline in leaves is caused by improper cultivation during the spring or summer unless it's during the colder months of the year, which is wholly natural. To dig deeper of its cause, think about your watering habits, where it's located in the house and what time of year you're currently serving. The plant's natural response to periods of droughts is to drop some of its foliage; fewer amounts of leaves will result in a reduced rate of photosynthesis and transpiration (water loss via the leaf).
Over-watering could also cause issues, as the roots won't be able to breathe due to the lack of oxygen in the soil. If you feel that either of these issues are to blame, be sure to rectify them quickly, as a continuation of your current watering habits will result in further decline.
Furthermore, situating it in a shady location will cause issues, too. If it's too dark to read a newspaper, it'll be too dark for an Oxalis, also. Increase the amount of light received slowly over the next week or so to reduce the severity of environmental shock, until the plant receives an hour of off-peak sunlight.
The final reason could be because of its dormancy period, served over the autumn and winter months. If the leaves have steadily declined over the last few months, it could be to do with the plant's response to a much-needed resting period. This is completely normal, and in some cases, all of the leaves may drop off. Simply keep the soil on the drier side until new growth appears in the early spring.

O. adenophylla is an alternative species for adding texture to a sunny basket or pot arrangement.

Origins

The O. triangularis is part of the Oxalidaceae family, which consists of 570 species, largely originating from South America. The name, Oxalis, derives from the organic compound (oxalic acid) found within its leaves and stems. The species was first described by Augustin Prouvençal de Saint-Hilaire in 1825, during a voyage to Central America. The leaves can be eaten raw or cooked and sport an acidic taste when eaten; however, you must be highly cautious as it can cause irritations for sensitive people.

Did You Know that like the Mimosa pudica, Oxalis are nyctinastic meaning that the leaves will move in concordance to the light levels. A slight difference between the two is that this species is actually bulbous, whereby the tubers can be divided during a transplant (every two or three years). For the UK, it's much harder to find these plants in garden centres, so the best bet would be to search the internet. If you're interested in keeping the Oxalis for years, have a read through the section above, as this will have lots of information about the much-needed period.

The Distribution of Oxalis triangularis

Temperature

12° - 24°C   (54° - 75°F)
H1b  (Hardiness Zone 12)  - Can be grown outdoors during the summer in a sheltered location with temperatures above 12℃  (54℉),  but is fine to remain indoors, too. If you decide to bring this plant outdoors, don't allow it to endure more than an hour of direct sunlight a day as it may result in sun-scorch and dehydration. Regularly keep an eye out for pests, especially when re-introducing it back indoors.

Spread

Up to 0.5m in both height and width. The ultimate height will take between 3 - 5 years to achieve, when quality dormancy periods are served in winter.

Pruning & Maintenance

Remove yellow or dying leaves, and plant debris to encourage better-growing conditions. While pruning, always use clean scissors or shears to reduce the chance of bacterial and fungal diseases. Never cut through yellowed tissue as this may cause further damage in the likes of diseases or bacterial infections. Remember to make clean incisions as too-damaged wounds may shock the plant, causing weakened growth and a decline in health.

Propagation

Via Seed or Tuber Division.

Tuber Division (Easy) is best performed during the dormancy period in the winter months. Of course, you can still propagate in the spring or summer, but you'll run the risk of transplant shock or damaging the delicate leaves.
Once the tubers are around 3cm in length, propagation can begin - have a look at the image below to see where to divide them. 

Oxalis tubers that can be cut or pulled apart along the blue dotted lines.

Take the plant out of its pot and place your fingers in between the two tubers; soil may have to be removed to get a better grip. Gently break them apart with a few sections of separate root systems. Place the new tuber around 1cm (0.4 inches) deep in a well-draining potting mix, much similar to the original soil, and maintain the same care routines. 'Houseplant' compost is acceptable, or you can make your own via using multipurpose compost with grit or perlite. Be sure not to use a pot that is too big; a ratio of roots-soil that much leans towards the latter will cause root rot. Keep the potted tuber in a bright, indirect location with slightly cooler temperatures - new shoots should appear in early spring, signalling the start of the new growing season.

Flowers

The flowers open in succession over of the course of spring and summer, and will typically sport a pink or white appearance. Each flower can last up to three to five days, folding up at night to prevent the pollen being blown away in high winds. To get an Oxalis to flower annually, a good dormancy period must be served over the autumn and winter months with cooler temperatures and drying soil.

Repotting

Repot every three years in the spring, using a 'Houseplant' labelled compost and the next sized pot with adequate drainage; this is the perfect time to separate the tubers into separate specimens. Hydrate the plant 24hrs before tinkering with the roots to prevent the risk of transplant shock. For those that are situated in a darker location, add a thin layer of small grit in the pot's base to improve drainage and downplay over-watering. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

Book a 1-to-1 video call with Joe Bagley if you'd like a personal guide to repotting your houseplant. This will include recommending the right branded-compost and pot size, followed by a live video call whilst you transplant the specimen for step-by-step guidance and answer any further questions!

Pests & Diseases

Keep an eye out for mealybugs, aphids, spider mites, thrips, blackfly, vine weevils & root mealybugs that'll locate themselves in the cubbyholes and undersides of the leaves, with the exception of the latter two in the soil. Common diseases associated with Oxalis are root or tuber rot, leaf-spot disease, botrytis, powdery mildew & southern blight - click here to learn more about these issues.

Toxicity

This plant is classified as poisonous when large quantities are eaten - keep away from pets and children who have tendencies to eat things. If parts of the plants are eaten, vomiting, nausea and a loss of appetite could occur, but is generally not considered highly toxic. 

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