If you’ve been interested in houseplants for more than a year or two, you probably already know the original “Pink Congo” story. A few years ago, a new plant called Philodendron “Pink Congo” came onto the scene. Its lower leaves are dark green, but the new leaves at the top are bright pink. It quickly became a wild hit among tropical plant enthusiasts and prices skyrocketed.
Then in summer 2019, it was suddenly revealed that the plant was fake – the pink leaves were chemically-induced and new growth would return to green after a few months. The houseplant community were outraged over this scam, and those who first broke the story called on people never to search for or reveal the exact treatment used, lest the deception be enabled to spread. The story even made it into mainstream media, like this now-paywalled article in Wired (an archived copy is visible for free here).
I’m coming to the story late, because it somehow passed me by the first time round. But when I eventually read about it, there were some strange aspects to the story that seemed to have never been resolved. So I did some digging and gathered all the information I could, to explain the whole situation.
This article will be in several parts, with convenient anchor links to jump between them. First, I’ll give all the information I’ve been able to find about the plant itself, how it works, and how it’s made. Then I’ll explain why I’m sharing this, and why I disagree with others’ insistence on secrecy. Finally, I’ll talk about why this happened in the first place, and what can actually be done in future to stop people being disappointed by artificially-treated plants.
The “Pink Congo” plant
First, an obvious but important fact check.
|“Pink Congo” is an artificially treated plant||The pink colour is chemically induced and temporary|
The pink colour is artifically-induced. The evidence for this is simply that every specimen has eventually returned to standard green growth – here is just one of many examples of a plant which is almost fully green after a year. Because it is artificially treated, the plant is not considered a cultivar, so its name is written with speech marks instead of single quotes.
Other than the objective evidence that all “Pink Congo” plants eventually turn green, we can also deduce that it must be treated based on some knowledge of how plants fundamentally work. All plants (aside from a handful of exceptions which have evolved to be parasites) get their energy from the sun. They absorb this energy using chlorophyll, which is the pigment that makes them green. If a plant doesn’t have chlorophyll, it simply cannot survive.
There are lots of cultivated plants which lack chlorophyll in some parts. For example, many variegated plants have streaks or patches on the leaves which are white (or pink, yellow, or cream) because they don’t contain chlorophyll. Other plants do not completely develop the chlorophyll in new leaves until a while after the leaf has formed, so young leaves appear white at first and gradually darken to green. These forms of variegation enable the plant to survive because, crucially, it still has some chlorophyll.
But “Pink Congo” isn’t like any of those plants. It doesn’t have leaves streaked with both pink and green. Its pink leaves don’t start off green, or turn green over time. When the plant is sold, the new growth is completely, permanently pink – those leaves have no chlorophyll at all, ever. If the entire plant was only pink, it would not be alive at all. When it’s sold, its lower leaves are green, and they are providing energy to the pink leaves. So something happens to the plant in between growing those first green leaves, and growing the new pink leaves. There isn’t any natural or genetic factor that could have that effect on the plant – it must be deliberately induced by growers.
So, the plant is artificially treated. Everyone is pretty much aware of that now (and most people have already been aware for two years because I am somewhat behind the times).
What everyone doesn’t know is exactly how the plant is treated. After a lot of research, I still don’t have a clear answer – in fact most of the information I have found just left me with more unanswered questions. Part of the reason for this is that the people who claim to actually have the information are insistent on not sharing it (more on that later).
One quote from a now-deleted post has been passed around quite a bit:
The product is Strepson, a form of Auxin, that, when applied as instructed, “stimulates ethylene production in high concentrations.”
Unfortunately, the central focus of this sentence is completely incorrect.
|“Pink Congo” is created using Strepson, a form of auxin||Strepson is not an auxin, and is not able to produce the temporary and uniform effect that creates “Pink Congo”|
Strepson is the commercial name for a product manufactured by Indo Biotech Agro, an Indonesian biotechnology company. I contacted them directly to ask what was in the product. Here is the entire (brief) conversation in the original Indonesian and auto-translated into English:
The active ingredient is colchicine, a highly toxic compound which was originally derived from crocus plants. Colchicine is not a form of auxin.
When it’s correctly applied to actively-growing parts of plants, colchicine can induce genetic mutations. These mutations are random and permanent. Sometimes the mutation kills the plant, sometimes it makes the plant larger or stronger, there is no way to predict the results. This randomness is used by plant breeders to produce new cultivars. If you mutate a large enough population of plants, eventually one of the mutations might be something desirable. And once a desirable mutation pops up, it can be propagated and maintained because the change is genetic.
It is not possible that Strepson was the treatment used for “Pink Congo”. Strepson creates permanent but random mutations, whereas the treatment that creates “Pink Congo” gives a temporary and repeatable result.
Ignoring the incorrect reference to Strepson, the rest of the sentence makes slightly more sense.
|“Pink Congo” is created using auxin which stimulates ethylene production||Auxin or ethylene may be able to create the “Pink Congo” effect, but there is no evidence to prove it|
Auxin is the name for a group of hormones which plants naturally produce. They are used to regulate growth and life cycles – telling the plant when and where to grow different structures like roots and flowers. In high concentrations, auxins trigger the production of ethylene.
Ethylene in turn is a gas which also acts as a plant hormone. It causes flowers to age, leaves to drop, and fruit to ripen. It’s the reason that putting a banana next to other fruits makes them ripen quicker – bananas produce lots of ethylene, and the ethylene triggers the other fruit to ripen.
Although the link between auxin and ethylene is well-recognised in botany and horticulture, I have not been able to find any information about ethylene causing leaves to lose chlorophyll. It has been shown to trigger leaves to die and fall off, and losing chlorophyll is usually the first stage in that process. So it’s possible that the method used for “Pink Congo” involves using ethylene to make the leaves lose their chlorophyll, and some other treatment to prevent the leaves from actually dropping off.
But without any concrete evidence, it’s equally possible that the process doesn’t involve ethylene at all. It might be some totally different treatment. Until someone shares an actual source describing the process used, we are ultimately all guessing.
I have not been able to speak directly to anyone who creates “Pink Congo” plants. They seem to mainly be produced in Southeast Asia so my own language barrier makes research difficult. If anyone else has first-hand information, relevant research papers, or contacts in the industry, I would love to know about it so I can improve this article! Feel free to get in touch.
Why I’m sharing this information
When it was first revealed that “Pink Congo” is artificially treated, people sharing the story emphasised that they were intentionally not giving the details of how it was done. There were even heartfelt pleas that anyone who knew the secret should keep it to themself and not make it public. But I could never work out what the justification was for that position.
People made vague implications that revealing the method would somehow make the ‘scam’ more prevalent. But surely, if having the information allowed anyone to create the plant themself, there would be no scam left because the plant would no longer be so difficult to obtain? In fact, the method is most likely very complex and probably involves regulated or dangerous chemicals and specialised equipment. If that’s the case, then just knowing how it’s done still won’t make it possible for scam artists to create the plant in their back garden.
In either direction, it makes no sense to suggest the scam would be made worse by sharing the method. Either sharing the method makes the plant accessible for everyone, demand drops, and there’s no market to sell it any more so the scam is over. Or sharing the method doesn’t help anyone actually create the plant, and the scam is simply unchanged.
The only motivation I can really think of to keep the information secret is some kind of elitism. The people who originally shared the story wanted to be the only ones who knew the big secret, so they gave a vague reason why the information shouldn’t be public. An even more cynical theory is that the people who broke the story actually benefited in some way from “Pink Congo” sales and wanted to keep their trade secret from being used by anyone else. I don’t believe that’s actually the case, but it’s a legitimate possibility to consider when someone is so reluctant to publish information like this.
If we ignore other people’s justifications, the simple fact is that providing information is the recognised way to combat misinformation. The Debunking Handbook written by 22 experts and scientists advises that misinformation has to be met with a detailed refutation. In other words, just saying “it’s a secret scam” is not as effective as saying “it’s achieved using this specific method which works in this exact way”.
I’m not a fan of elitism or secrecy, and I am a fan of science. So I’m sharing all the information I have, as well as everything that I don’t yet know or don’t understand. Maybe other people will have slightly different information they can share, and when we work together we’ll all have a better understanding of everything. What’s not to like?
It probably wasn’t a scam at all
Most discussions of this situation are based on the assumption that “Pink Congo” is a scam – a deliberate attempt to trick people into spending money on something that won’t last. But in fact there’s no evidence of that either. It’s more likely that it began as a simple miscommunication, caused by a combination of factors in the way the plant world works.
The industry of growing and selling ornamental plants has obviously been around for a long time. For most of its history, houseplants have been only a very small part. The majority of plants being bought and sold are used outdoors in gardens. Some are trees and perennials, which are planted permanently in one place with minimal management. And others are bedding plants, which are planted in spring and die off by autumn. Until recently, indoor tropical plants were mostly treated like decor – buy a plant that looks nice at the time, keep it until it gets ugly or dies, then replace it.
The recent boom of houseplant enthusiasts has created a completely different type of demand for plants. Instead of choosing a plant based on how it looks at the time, people become collectors and seek out specific species or cultivars – even in the form of cuttings or seeds. Instead of keeping a plant for a few months and discarding it when it’s no longer attractive, people prune and nurture their plants with the aim of keeping them alive and healthy forever. Of course, collectors have always existed in specific groups of plants (think “tulip mania” or orchid collectors), but never at the scale of today’s houseplant community.
And this change has happened so quickly that the global industry which produces plants hasn’t changed to match it (yet).
Mass producers are used to creating plants which look visually appealing at the point of sale. Artificial treatments are commonly used to keep bedding plants bushy or to make trays flower at the same time. And providing information to the buyer is rarely a priority – because historically most buyers don’t care very much about the scientific name of their pot plant or exactly how it was grown. They just buy it because it looks nice.
The new houseplant industry has prompted lots of new houseplant retailers to meet the demand. But although those retailers are targeting modern collectors, they are largely still getting their supply from the same international mass producers. So even though houseplant shops might be trying to provide accurately-identified and longlived plants for their customers, their suppliers are still doing what they’ve always done – making plants that look nice at the point of sale.
This results in strange conflicts. The grower prints “Tradescantia albiflora” on the label because they have to print something and it’s the label they give all their tradescantias. The retailer buys a batch of plants and carefully copies down the names from the labels so their customers can see the plant’s correct identity. A buyer orders the plant and is horrified when it develops a pink flower, instead of white as the “albiflora” name suggests – the plant is a scam! Except they haven’t really been scammed. There was just an unfortunate sequence of miscommunications that no one is to blame for.
The same goes for plants which have been given growth treatments, like the infamous Tradescantia ‘Nanouk’. The grower doesn’t bother telling the retailer that the plant has been treated or how. The retailer crafts a detailed product listing, photos, and description of the plant they received to sell on – with the assumption that its current state is how it will continue to grow. And then the buyer feels misled when the plant they order ends up growing much bigger leaves and longer stems than they ever expected.
And the same most likely goes for “Pink Congo” too. The grower found a way to make a plant that looks very interesting for a short while. They know people will like the look of the plant and use it as a temporary decoration. They probably have no idea (or at least no interest in) the market of houseplant collectors who are interested in specific plants to grow long-term. They sell on their batches of plants to wholesalers who pass them on to retailers, and eventually the plants end up in a shop targeted at houseplant collectors with no information about how the plant was created.
The real cause of this type of issue is simply that plants are mass-produced (often internationally), and travel through many levels of wholesalers and suppliers before reaching their final owners. Houseplant collectors might feel like a friendly houseplant-focused shop is really targeted at them. But the truth is, unless the shop actually grows all of their own plants, they are probably buying from just the same wholesalers as any big garden centre or DIY shop.
That’s not necessarily a problem. Big plant producers know what they’re doing – they can efficiently (cheaply!) produce lots of plants, create new cultivars, and distribute them around the world. But it’s important to be aware of where your plants actually come from. Unless you’re buying directly from a nursery or grower, the plants are probably mass-produced and imported. And that means that the information that comes with those plants is probably not very reliable. Don’t take it personally if a plant seems to be labelled wrong, or if its future growth is not what you expected.
If the exact identity and growth habit of a plant really matters to you, it’s always better to buy directly from a grower. Small-scale growers and collectors will usually charge higher prices, because they aren’t mass-producing in the same way. But what you get in exchange for those higher prices is the opportunity for really clear information about what your plant is, how it grows, and where it really came from.
And finally, if you are interested in plants or growing them yourself – always share as much information as you can! Anything one person learns can benefit everyone, if we all share our knowledge. Secrecy and elitism of information doesn’t solve anything.