Recently a member of my bonsai club was talking about this product, HB-101. It is apparently wildly popular in Japan and supposed to be fantastic for bonsai. It claims to be an “all-purpose natural plant vitalizer”. Since plants synthesise their own requirements for growth from the 17 nutrients, I couldn’t really see how this would work unless this product was a fertilizer, so wanted to dive a bit deeper into this product to work out what it does. Unfortunately the product website is pretty waffly, or possibly just poorly translated, so a bit of investigation was required.

According to the manufacturer HB-101 is made from “essences of such long-lived trees as cedars, Japanese cypress, and pines as well as from plantains.” Without knowing how they define ‘essences’ and which bit of the plantain they use, this doesn’t help much. But more info is in their submission to the United Nations Industrial Development Organisation: “HB-101 is synthesized from organic distillate, which is extracted from the heated raw material of cedars, Japanese cypress, pines, and plantains as raw materials”. So it contains substances from Cryptomeria japonica (Japanese Cedar), Chamaecyparis obtusa (Japanese Cypress) and Pinus thunbergii (Japanese Pine) as well as plantain grass (not plantains like bananas).

In their safety data sheet it shows the product has a pH: 3.0 ~ 4.5, and is toxic to fish, daphnia and other aquatic invertebrates within 48h at 1% concentration or more. The product explanation from the UN submission contains more useful data including a typical analysis chemical breakdown:

• Kaempferol; 0.1 ~ 0.2 ppm
• Water-Soluble Nitrogen (as N); 0.001 ~ 0.005 %,
• Water-Soluble Phosphoric Acid (as P₂O₅); 0.0001~ 0.0005 %,
• Water-Soluble Potassium (as K₂O); 0.0001 ~ 0.0005 %,
• Total Sulfur (as S); 0.0001 ~ 0.001 %,
• Calcium (Ca); 0.5 ~ 3 ppm,
• Magnesium (Mg); 0.3 ~ 3 ppm,
• Iron (Fe); 0.01 ~ 0.05 ppm,
• Zinc (Zn); 0.01 ~ 0.05 ppm,
• Silicon (Si); 1 ~ 5 ppm

Based on this breakdown, the product appears to be mainly a nitrogen fertilizer (NPK of 10:1:1) which includes all six macronutrients (nitrogen, phosphorus, sulphur, potassium, magnesium, calcium), and two micronutrients (zinc, iron). It also contains two non-nutrient ingredients – silicon and Kaempferol.

I was surprised to see silicon in the list as it’s not considered one of the 17 required plant nutrients. But a bit of digging and apparently it “activates plant defence mechanisms” and “increases the resistance of plants to pathogenic fungi”^ref. Interesting! Looks like I will need to write a new post on non-essential-but-benefical nutrients…there are bound to be others aside from silicon.

The other ingredient is Kaempferol. Kaempferol (in case you were wondering) is a flavonoid (substance synthesised by plants) which “has a role as an antibacterial agent, a plant metabolite, a human xenobiotic metabolite, a human urinary metabolite, a human blood serum metabolite and a geroprotector.”^ref It has a molecular formula of C₁₅H₁₀O₆. Flavonoids are “pigments that color most flowers, fruits, and seeds”^ref and they are actually produced by plants themselves, so it’s not obvious to me why adding them to a plant would do anything.

The product explanation claims that Kaempferol ‘activates plant mitochondrial enzymes’. Looking into Kaempferol further, it is referenced in a wide variety of human disease research, including cancer^ref and brain injuries^ref. It does indeed appear to affect the function of mitochondria and provide protection to cells against injury – at least in humans. In this article Kaempferol is said to protect against oxidative stress and various forms of toxicity by affecting mitopaghy (the removal of damaged mitochondria), suppressing fission (cell reproduction) and apostosis (cell death). In humans it seems to have the almost magical property of helping healthy cells to survive while inducing the death of cancer cells^ref.

Admittedly plants (like all complex life) do contain mitochondria, which generate the energy needed to power cells. So if a substance affects mitochondria in people, it may well have similar effects in plants. The question is whether externally delivered Kaempferol can actually enter the plant and get into its cells, which it would need to do in order to make any difference. As flavonoids are synthesised by plants, and since plants don’t absorb this kind of substance – instead absorbing the raw materials to make it themselves – I don’t think Kaempferol can be having any impact on the plant mitochondria.

BUT – what it might be doing is having an effect on other living things that affect tree health. And hey presto, a bit of searching uncovered that Kaempferol has been shown to improve root development by supporting Arbuscular Mycorrhizal Fungi (AMF) ^ref – this is a type of fungi in soil which can help expand the volume of soil from which nutrients can be extracted (Thomas).

In one study a range of flavonols were tested for their contribution to the growth of mycorrhizal fungi and Kaempferol was shown to make a modest improvement^ref but another flavonoid called Quercetin was even better.

Kaempferol does come from conifers which are in this product’s ingredient list. But it’s also high in green leafy vegetables like spinach, kale and dill^ref. So my guess is that a lot of it comes from the plantain grass in this product. Quercetin, which was more effective for nurturing mycorrhizal fungi, is apparently found in red, green, and purple-pigmented plants – for example, red onions. Unfortunately though, it seems that Quercetin (and Kaempferol) are not very easy to extract – industrial methods (likely the one used for HB-101) require ethanol but if you’re keen here is a method using ‘subcritical water’ (liquid water under pressure at temperatures above usual boiling point, 100 °C (212 °F)

So what else might the cypress, pine and cryptomeria be contributing? The company’s product page gives a few other clues – specifically it mentions saponin, pine oil and succinic acid, although these are not listed on the chemical analysis data sheet.

Saponins are substances produced by plants which are “responsible for plant defense against antagonists; such as mollusks, pathogens and insects”^ref They are contained in a wide range of plants but do not appear to be present in conifers^ref. By contrast saponins are found in plantain grass (and actual plantains!)

Looking at what the conifers are providing to this product – pine oil has larvicidal and mosquito repellent properties^ref, Cryptomeria japonica oil is insect repellant and insecticidal^ref, antifungal against tree pathogenic fungi^ref as well as antimicrobial^ref and Japanese Cypress oil is antibacterial and antifungal^ref (and apparently also good for hair loss!).

And finally, succinic acid. This has been shown to improve tree tolerance (in Larix olgensis) to heavy metal contamination – specifically with Lead^ref and Cadmium^ref. This doesn’t seem to me a particularly useful attribute for bonsai, since we’re using inert bonsai medium. Dig a bit further and you find succinic acid was combined with 2,2-dimethylhydrazine to make a plant growth regulator called Daminozide (also known as Alar). It regulated the growth and set of fruit but has been banned due to concerns about cancer risk. This isn’t on the ingredient list so I don’t think it’s present in the product. I can’t find much useful information on what succinic acid might be contributing.

So what’s my overall analysis? Initially I was sceptical because I don’t like products that rely on fluffy advertising and don’t explain how they work. It annoyed me that the product doesn’t contain an ingredient list, and it doesn’t admit to largely being a fertiliser, which is most definitely is.

However one of the key features of this product is that parts of it are derived from a distillation process, which enables the extraction of beneficial compounds from the conifer leaves and wood as well as from the leafy plantain grass. These should help boost a tree’s defences to insects, pathogenic microbes and fungi, and improve the mycorrhizal activity in the pot to supports better root development (and thus healthier trees). It also has a lot of nitrogen, which as outlined in nutrients is hard for plants to obtain.

So somewhat grudgingly I have to say it might actually work.