Euphorbia Trigona (African Milk Tree Plant) Guide (2024)

A bit about Euphorbia Trigona

Euphorbia Trigona, or the African Milk Tree as it's commonly known, is a highly architectural and curious houseplant. Easy to look after, pest resistant and a fast grower means it makes the perfect specimen that adds interest to a sunny spot.

Like many in the Euphorbia genus, it's a mix between a cactus and a succulent plant but has traits familiar with both. It's easy to treat it like a cactus accidentally, which can cause problems for new owners, but if you follow our care guide further below, you'll be fine.

This guide will tell you everything you need to know about growing Euphorbia Trigona.

The "Trigona" name comes from the plant's stems which have three distinct sides creating a Triangular effect (if it has four sides, you may have a Euphorbia Acrurensis instead).

As each side reaches the edge, it rounds out slightly to create a ridge. Along the ridge, two thorns will form every cm or so and in between those, a leaf will normally grow.

The leaves have a teardrop shape and tend to be present for only short periods, a growing season or two. If you provide poor care, then the leaves will be the first to drop off.

Even if you end up with a leafless stem, it's still a striking and handsome houseplant.

How do you pronounce Euphorbia Trigona correctly? Say:
yew-FORB-ee-ah try-GOH-nuh

Like the majority of Euphorbia plants, they really don't like being touched or played with. The thorns will deter most people and pets, but if this isn't enough, it will ooze a latex sap that's both unpleasant to taste and also highly irritating to eyes and mucous membranes like those found in the mouth .

If you can live with those negatives, it's an adaptable houseplant that only has basic and simple to follow care needs. In return it will grow pretty fast and provide all-year interest.

Buying Euphorbia Trigona Plants

You can buy two main varieties, and both are pictured in the first photo at the top of this article. The all-green variety is E. trigona and as this name description implies is entirely green, almost a lime green at times. You'll get some mottled patterns on the stems but otherwise it's pretty plain.

The other is E. trigona rubra (sometimes sold as Royal Red), which has a rich and varied colored palette. It has flushes of deep red, almost burgundy on the leaves and stems, but this coloring can become less pronounced or deeper depending on the light levels you provide.

Either way, both varieties are quite beautiful due to their structural upward growth habit and thick triangular-shaped stems.

These are less commonly sold houseplants and the struggle to find one, is often real. On the plus, they're easily propagated and grow fast, meaning they should be reasonably priced when you do come across them.

Plants sold as a single upright stem might look quite small, but you can easily train them into something much larger with many branches over a number of years.

You can find both varieties for sale on Etsy*. I've also seen them for sale on eBay*.

*Our website is free because our users support it (thank you!). We'll sometimes earn a small commission when you buy something through the affiliate links on our site.

If you do find one for sale in a store, make sure you pick a healthy and attractive one. The below gives you an indication of what good vs bad care looks like.

Use the slider above to tap / swipe back and forth to see the difference between a well looked after vs a poorly treated plant

That's the basics out of the way so let's move on and look at how to take care of and grow a Euphorbia Trigona the right way.

Euphorbia Trigona Care and Growing Guide

Light

You'll find lots of conflicting information online. Some say put them outside and give them full direct sunlight all day long. Others say this will burn and damage the plant and will only tolerate a little sun even if grown indoors.

From our experience both pieces of advice are partly true. So our advice is as follows.

These are succulents and not true cacti, so intense pounding sun isn't something your plant wants or will enjoy. Coming from Central Africa, they're well adapted and expecting to deal with heat and some sun though, so they do need either bright light all day or some sunlight for an hour or two.

You can also put them outside during Summer providing the location you pick for it gets at least some partial shade.

You should not suddenly move your plant into intense sunlight if it's been in a darker spot for a while, or you'll risk scorching. Get them acclimatised for a week or so by moving them into the sun for an hour or so a day then back into shade again, gradually increasing the time in the sun.

Even plants grown in good light levels might have some of these issues if the light is only coming from one direction. If this happens, rotate the planter 1/4 turn every week or two for more consistent growth.

Watering

There are two main reasons this plant does poorly in some people's care and that's normally because it's mistaken for a cactus. New owners might assume it needs as much sun as possible and that it barely needs any water. Wrong on both accounts.

We covered the light issue above already and the water needs are as follows.

When they're very dehydrated, you might notice the stems seem a little soft to the touch. Once well watered and about 5 hours later if you feel the stems again they will feel full and puffy.

They can be easily overwatered, so if there is any doubt whether your plant needs a top-up or not, wait a few more days to be safe.

A young multi-stem all green Euphorbia Trigona that will make a beautiful potted plant

Humidity

Almost any humidity you find in a standard home is going to be okay for these plants providing there is good air circulation. If combined with overwatering, you may run into issues with excessive humid and stale rooms, but otherwise, you don't need to give this a second thought.

Feeding

While not overly hungry, it will still love you if you can provide a well balanced feed every few months whenever it's in active growth. Use a standard houseplant feed or one designed for succulents and cacti.

Temperature

They prefer warmer or even hot temperatures, but will still put up with some cool ones too. If temperatures are too cold, don't expect any growth and cut back on the watering to ensure you minimize the risk of root rot.

It can survive temperatures approaching freezing if necessary, but it's not a truly hardy plant and prolonged exposure will almost certainly cause some damage.

You'll get substantial growth if your plant gets warm or hot temperatures.

Repotting

Young small plants will normally be growing fast and they will need repotting once a year until they become more significant. At this point, you should be fine to repot it once every two or three years.

You'll get significantly more visible growth compared to the space the roots need. This basically means it's normal for larger plants to be in comparatively small containers.

This can be quite worrying, but after a few weeks, the soil settles down and the roots will stabilise into place again.

What kind of soil does African Milk Tree Plants need?

You can grow these plants in a wide range of growing mediums. Regular potting compost or soil, sandy soil and special mixes labeled for cacti and succulents are all fine, basically the mix should be a type of well-draining soil.

Avoid using anything too compacted or heavy such as 100% topsoil as the roots do prefer some natural drainage. Equally, remember they do like their water, so if the mix you're using is too "open" and free-draining you'll be watering much more frequently.

Watch my YouTube Video for more visuals showcasing aspects of this plant that I couldn't capture in photos

Propagation

You'll not be able to create new plants by seed (see the "Flowers" section below to find out why), but it's straightforward to make new plants through stem cuttings.

All you have to do is cut off a newish stem, no older than two years is best. The stems will be pretty fleshy so you'll probably have to use a knife or pair of secateurs instead of scissors which just won't cut it (pun).

There will be some serious milky sap leaking out when you do this so before you start, make sure your work area is covered and you've protected yourself and your eyes in case any of this comes in contact with your face or skin.

Once the edge has dried out push the cutting just a few cm's or an inch into a soil mix similar to whatever the parent plant was growing in. Keep the soil just moist and in similar environmental conditions and before long new roots will establish.

Speed of Growth

Expect your plant to have bouts of growth, up to a foot each year is possible on very happy plants. At certain points during the year you'll notice it getting taller, fast. Then it'll suddenly go dormant and not move a muscle for months.

It's easy to see when this is happening on theRubravariety as the new growth is often a lighter shade of green so it stands out from the rest of the plant.

I've seen observations and comments made elsewhere telling people this is a "problem" and it means it needs more bright sunlight and to put it outside in full sun, but this isn't correct.

The Euphorbia trigona Rubra or "Royal Red" variety will produce new growth that's initially green. It will normally darken in time.

New green growth without the red hues, by itself, is not a sign you need to provide more light. Think about it. Your plant is clearly happy with its situation or it wouldn't be growing in the first place!

This different shade of green will darken over the season as the new growth hardens off. Just plopping it outside in full sun could scorch it instead, so don't do this.

How big does the African Milk Plant get?

Most houseplants don't get overly tall in an average home for many different reasons, but Euphorbia Trigona is different as it's a serious grower and heads upwards.

If there is enough space and the planter is big enough they will easily reach 5ft or more after about 5 or 6 years.

Growing your plant in a smaller pot will restrict this growth and you'll keep it shorter and contained for longer.

You can also cut the main growing stem to encourage bushing or more "arms" to form. This will again restrict the height (because you're chopping it off) and add density and width to your plant.

These plants will get pretty tall after a few years - Photo by Mark C

Flowers

No flowers here. One of the very few plants in the world which are believed never to have flowered. For this reason it's considered this is a hybrid of some sort. Regardless, don't expect to see any blooms on it any time soon.

Is the African Milk Tree safe around pets?

These plants will do everything they can not to get eaten or played with. Their natural defenses mean they're not safe around pets or children who play or try to eat houseplants.

Even if you have perfectly behaved pets or kids, you still need to locate your plant out of high traffic areas with a lot of potential for brush past, this is because they could accidentally knock them over.

What to watch out for

How do you get the plant to become bushy and full?

If left entirely alone, the main stem will grow taller and taller, producing one tall single column. It may occasionally put out side stems or "arms" by itself but in general this has to be encouraged.

It's far more common for owners to grow them with multiple "arms" as this creates a more visually appealing and full looking houseplant. Producing this look is easy. All you need to do is lop the top off of a growing stem in Spring. *** It's never happened to me, but I've read that when some people cut into the stem, the sap can spray out! Take care of your eyes when working with it ***.

In my experience, I'll generally get two new stems forming, but I've seen very healthy plants producing three or more.

You could cut the stem at different points during the year too, but you may not get any new growth forming until the following Spring.

I'm currently experimenting to see if the time of the year or if the thickness and age of the cut stems make a difference. If you're curious about my findings check back in the future for an update. In the meantime if you have any thoughts or direct experience, get in touch or comment at the end of this article.

Cutting the top of one of the stems or "arms" will often cause new ones to grow.

Once the new stems have grown to a fair size.... you can cut these too! The result is even more "arms" and a very dense look.

I've not tried it personally as it's been reported to be hit or miss (I want guaranteed results!) but you can also just "nick" or cut small sections of the stems out by about 1cm / 0.5 of an inch. This introduces damage that again new shoots will sometimes grow from.

Anything else?

When they're small, they can be quite dainty and pretty looking, suiting small pots. However when grown in excellent conditions they do grow tall and will do so rapidly and when this happens they'll become very top heavy.

A strong gust of wind or a gentle knock and it will be on the floor before you know it. I can't stress enough that you should really plant these up in heavy containers. A terracotta pot would provide good support, but equally you can use pretty much anything other than lightweight plastic. The heavier the better.

If it happens to you, don't feel bad. It took me three times of picking it up off the floor before I finally switched to a heavy pot!

These plants will get top heavy quickly. Don't get caught out using a plastic pot as a gust of wind will blow them over.

Problems and Common Issues

Yellow Leaves / No Leaves

One of the common, if not the most common issue Euphorbia Trigona owners will come across are the leaves yellowing up and falling off.

Yellowing and leaf drop is a commonly reported problem.

We try not to be vague when giving help, but the truth is that the leaves never seem to last forever and even slightly incorrect care for a short period can cause this problem to occur. It seems to happen when one of the below has happened.

Stems bending towards light

This is a good indication your plant is struggling for light. However you might not need to move it somewhere else providing you still feel the location is "bright", for example if it's right up against a window.

Light which is coming from one direction, such as that from a window, will still cause slight bending and you'll notice all new leaves will turn to face the window. All you need to do is rotate the pot 1/4 turn every few weeks to keep things even.

Clearly if the location is set quite far back from light sources you may have no choice but to relocate it to a sunnier position.

Plant losing color

If your Euphorbia Trigona has lost some of its markings or you notice the red hues on the Rubra variety are fading it is normally because the light levels are too low. To rectify this, move to a brighter spot, or gradually expose it to more intense sunlight.

New growth will typically be green and have less vivid markings. Don't worry - this is normal.

Corking

The majority of the plant surface will have a fleshy "live" quality about it. But sometimes corking will happen, resulting in a scabby, brown color accompanied by a thickening of the plant's tissue. The affected area will look dead and potentially will even be mistaken for a disease.

"Corking" is common on cactus plants but can also form on succulents

Some corking on older plants is entirely normal and just part of the plant's growing cycle. However I would expect to see this on older growth first.

In the photo above, you can see the browning and damage has happened at the top of a stem, while the older growth below this point is fine.

When this happens it's much more likely this browning is the result of sun damage, in particular too much of it. Again whilst it's "natural" it can spoil the overall look and can't be "fixed".

All you can do is prevent it in the first place or stop it from getting worse if you notice it happening. If you spot any damage just starting, you should move it somewhere with more shade immediately.

Pests

One of the most pest-resistant plants I've owned. My collection has never had any (touch wood)! They aren't common, and any you do come across should be easy to deal with.

Visitors have commented on the root ball area being afflicted by Springtails occasionally, although they're not a massive problem in the grand scheme of things. Spider Mites could also be an issue in very arid climates.

Rotting

Root rot can occur fairly quickly if your African Milk Tree has been sat around in wet soil for a prolonged period. Basically it's been overwatered quite extremely for this to happen.

If you're prone to doing this with your houseplants you're not alone, but be sure to use a container with drainage holes and always allow the top couple of inches of soil to dry out before you water again.

If the stems are very mushy at soil level, there isn't much you can do. Consider using any firm material from higher up the plant for propagation to create replacements.

Why is my African Milk Tree going brown?

The most likely cause is too much direct sun combined with underwatering. This can cause some quite ugly damage. Read about these problems above (corking) and also go through our care guide in regard to light and water needs. This should prevent further problems. If you're still not sure, leave us a comment at the end of the article.

Our story with this houseplant

When I was about 10 years old, my parents took me to a Garden Centre which had a hugely impressive succulent and cacti display.

In my life, up until this random Saturday (as far as I can remember at least), plants had been pretty kind to me. But that was all about to change.

I saw a "furry" cactus and reached for it. Grabbing with a fully open hand and squeezing. All I got for my trouble was a fist full of glochid spines.

I spent the rest of that afternoon in the bathroom soaking my pin cushion of a hand, in warm water every few minutes while my mum had to tweezer out every last one. There must have been over a hundred at least! Not a good memory.

This was my first experience that some houseplants just weren't all that nice to have around, and subconsciously or otherwise I've never been a fan of thorny plants. So in all honestly I've only really met Euphorbia Trigona in the last few years.

A two or three year old healthy looking pot plant growing in an attractive container.

It was the Rubra Cultivar that caught my eye, it looked like a cactus, but had leaves, and that beautiful red hue splashed all over it just drew me in. Before long I had three in my collection including the all green variety which I love, as the contrast between the two different looks really help make each one stand out.

Did it completely change my mind about thorny plants? No, not totally. I still found it would smart when handling it, such as trying to grab the odd brown leaf squeezed between two stems, but I'm an adult now and a fast learner (I use tweezers for this job now!). Protect yourself around the thorns and you'll avoid the negative aspects.

Then all you're left with is the positives. It has a robust vertical footprint. Many indoor plants tend to spread outwards, so not only does the Trigona have an attractive architectural shape, but it's a "water it and leave it" kind of houseplant that grows fast, stands out and commands attention.

All things considered I think over the next few years you're going to see more Euphorbia plants on the site.

Also on Ourhouseplants.com

Credit for all green plant photo growing in a hallway to Mark C - (Read about his plant experience in the comments below)

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