Why I do recommend superthrive- and products alike

11 March 2026 -

There is a product sitting on the shelf of almost every serious plant hobbyist. It comes in a bottle, requires only a drop or two per litre, promises extraordinary things, and has been passed down through orchid societies, garden clubs and online plant communities for decades as something close to gospel. You probably know it. You may already own it.

The product is SuperThrive, first sold in 1940. And the category of plant supplements it spawned — vitamins, amino acids, vital substances, biostimulants — has never really been questioned. It just grew.

This post is the question.

A Myth Born in a Petri Dish

The origin of vitamin B1 supplementation in plant care is a story worth knowing because it explains almost everything about how the myth survived.

In 1930, a researcher discovered that thiamine — vitamin B1 — stimulated root growth in excised plant roots placed in a laboratory culture medium. The finding spread quickly. By 1939, Better Homes and Gardens was reporting that B1 produced giant daffodils and huge rose flowers. The myth was launched and the market followed immediately.

Here is the part that tends to get left out: by 1942, the original author of the study had already retracted the premise. In his own words — "it is now certain that additions of vitamin B1 to intact growing plants have no significant or useful place in horticultural or agricultural practice."

The study had been conducted on isolated root fragments in sterile media. Not on intact plants. Not in soil. Not under any condition that resembled actual cultivation. When researchers subsequently tested B1 on whole plants — mums, apple trees, orange trees, tomatoes, beans, pine, pepper, corn, pear, watermelon and squash — they found no discernible growth response. One study found root growth was actually greater in the control treatment receiving only water.

The reason is straightforward plant biology. Unlike animals, plants synthesise their own thiamine. They do not have a dietary requirement for it. The leaves produce it and translocate it to the roots. There is no deficiency to correct and no uptake mechanism that makes exogenous B1 application meaningful to the plant itself.

The retraction came in 1942. The product launches came anyway. And eighty years later, vitamin B1 is still appearing in the ingredient lists of premium plant supplements, still being recommended in orchid forums, still sitting in hobbyist grow rooms around the world.

What SuperThrive Actually Did

SuperThrive's commercial success was not built on B1 alone. The active ingredient that actually does something in products like it is 1-napthaleneacetic acid — a synthetic auxin with genuine effects on root initiation and development. That is a real mechanism. The auxin earns its place.

The B1 was, by most evidence, always a marketing ingredient. It sounds wholesome, it sounds scientific, and in 1940 the distinction between "this compound is essential for animal metabolism" and "this compound does anything for intact plants" was not widely understood outside specialist literature. The public knew vitamins were good. Plant vitamins sounded logical.

What SuperThrive established was a template that is still being followed: take a compound with a legitimate biological role somewhere in the scientific literature, associate it with plant health through implication rather than evidence, package it with a dramatic application rate and confident language, and let the community do the rest.

Then Why Do People Swear By It?

This is the more interesting question and the honest answer requires going somewhere the marketing description never goes.

Take the Hesi SuperVit description. It reads: "The vital substances are also growth promoters for the microorganisms in the substrate. This creates strong networks between the plant, the substrate and the microorganisms in it."

That sentence is buried at the end of a paragraph about magical plant energy levels and saved metabolic steps. It is presented as an afterthought. It is actually the only scientifically defensible claim in the entire description — and it points toward a world of biology that the product is accidentally feeding without understanding it or choosing to explain it.

Because while B1 does essentially nothing for an intact plant, and while the amino acid concentrations in most supplements are too low to meaningfully alter plant metabolism directly — the microbial community living in your substrate is operating at an entirely different scale. And for that community, amino acids and vitamins are not a luxury. They are currency.

The Actual Story: What Lives in Your Substrate

Healthy growing media — particularly organic substrates like sphagnum, bark, and leaf litter mixes — is not an inert physical support structure. It is a living system. Bacillus species, beneficial fungi, nitrogen-fixing bacteria, and dozens of other microbial partners are establishing colonies throughout the root zone, forming networks, communicating through chemical signals, competing for territory, and collectively performing functions that no single input product can replicate.

These microorganisms are not passive beneficiaries of a coincidentally friendly environment. The plant is an active participant in building and maintaining the community around its own roots. Root exudates — sugars, organic acids, enzymes — are specifically calibrated to recruit beneficial species. The plant is, in a very real sense, farming its own microbiome.

And that community has genuine nutritional requirements.

Bacteria utilise amino acids as both nitrogen and carbon sources. In a competitive substrate environment, the availability of preformed amino acids reduces the metabolic cost of biosynthesis, which translates directly into faster growth rates and higher population densities. This is not a marginal effect — nitrogen acquisition and amino acid metabolism are central to bacterial ecology. Beyond simple nutrition, amino acids also function as chemoattractants. Bacteria actively move toward amino acid gradients in their environment, which influences how effectively the community colonises root surfaces and maintains competitive pressure against pathogens.

This is where a product like SuperVit may actually be earning its place — not by turbocharging your plant's metabolism, but by providing a modest nutritional stimulus to the microbial community that your plant depends on. The plant looks better because the invisible world beneath the substrate is slightly more vigorous, slightly more densely colonised, slightly more effective at excluding opportunistic pathogens and cycling nutrients into plant-available forms.

The product works through an intermediary that the marketing does not mention.

A Note on Thiamine and Microbes

It is worth being honest about the edges of this argument. Thiamine auxotrophy — the inability to synthesise one's own B1 — is genuinely common in the microbial world. Many bacteria cannot produce thiamine and depend on external sources. This is well established in gut microbiology and other contexts.

Whether any specific beneficial rhizosphere inhabitants are meaningfully thiamine-limited in a healthy organic substrate is a more difficult question. Soil and substrate bacteria are largely environmental generalists selected over evolutionary time in thiamine-rich environments where decomposing organic matter, plant root exudates, and fungal networks all contribute thiamine naturally. The probability that a well-maintained sphagnum substrate is thiamine-limited to a degree that external supplementation makes a measurable difference is probably low.

This is a knowledge gap worth acknowledging rather than papering over. Actual research on thiamine requirements of specific rhizosphere species in indoor growing contexts does not exist in the hobbyist literature that I could find. What can be said honestly is: the mechanism is plausible, the evidence is insufficient, and we are not going to speculate further than that. If you want to include B1 in your routine on the grounds that some substrate inhabitants might benefit, that is a reasonable position. Just know it is one step beyond what the current evidence supports.

So Should You Use It?

The reframe here is not "stop using amino acid and vitamin supplements." It is: understand what you are actually feeding and why it does help. And in all honesty I use it exactly for the reasons stated before.

If you have a biologically active substrate that you are actively cultivating — if you are using organic or semi-organic media, if you are avoiding broad-spectrum biocides, if you have an established and thriving root zone — then a small regular input of amino acids represents a modest nutritional stimulus to the community already doing the most important work in your pot. The concentration does not need to be high. Bacteria are working at a scale where trace inputs are meaningful.

The product works in a way, just not the way the product is being marketed.

I do want to note that the products have been tested by multiple hobbyist that did not see a difference at all.

The Bigger Picture

The vitamin and amino acid supplement category exists largely because SuperThrive made it commercially viable and culturally embedded before anyone was asking hard questions. The template was established: concentrated formula, dramatic application rate, scientific-sounding ingredients, extraordinary claims. Products have been following it ever since.

This is not a reason to dismiss everything in the category. It is a reason to read the label with the right question: what is this actually doing, for what, and through what mechanism?

Amino acids feeding your substrate microbiome is a real mechanism with genuine biological support. Vitamin B1 turbocharging your plant's root development is an eighty-year-old myth that its own originator abandoned before most of our grandparents were born.

Your substrate is alive. What lives there matters more than any bottle on your shelf. Feed the biology, understand what you are feeding, and the plants will follow.

Further reading: Chalker-Scott, L. The Myth of Vitamin B-1. Washington State University Extension. International Journal of Plant Sciences, Vol. 102, No. 1 (1940) — Hamner CL.