Snake Oil is an old-school term for a cure-all potion, that in reality does nothing. If you are lucky the potion won’t make things worse but the chances of it making things better are slim – ‘that which doesn’t kill you, makes you stronger’, or in the case of Snake Oil, ‘that which doesn’t kill you leaves you physically unchanged but financially poorer’.

Science and the Consumer Guarantees Act have put a stop to most of today’s Snake Oils but ‘click-bait’ and advertising channels are filled with wonderous products purporting to be able to do this, that and everything in between – modern Snake Oil if you please. That which doesn’t kill you, you can return in 30 days if you are not completely satisfied… Today’s Snake Oils come with a money-back-guarantee and a free set of steak knives.

To avoid legal proceedings, the producers of these wonderous things must be able to substantiate their claims, there must be least a smidgen of truth about what they can do, or at least the appearance of a smidgen of truth (scientists say, users agree).

In the world of horticulture, calcium seems to be the new thing, the thing that all our plants need. The primary function of calcium in plant growth is to provide structural support to cell walls, calcium is an essential element (scientists say plants need calcium). But wait, there is more, calcium also serves as a secondary messenger when plants are physically or biochemically stressed (calcium cures plant stress). Cellular responses to specific biotic and abiotic stimuli are calcium-dependent (plants are defenceless without it). Calcium is the perfect storm, the marketer’s dream; scientists say the calcium is essential for plant growth, cures stress and plants are defenceless without it, just add scientifically formulated X, patent-pending and you’ll see results. And for marketing trifecta… you may actually see results – depending on where on the plant you look, calcium deficiency may present as abnormally yellow or abnormally dark green. Luckily for sales, the dark green bits are at the bottom of the plant and nobody looks up.

Calcium is indeed the thing, the thing that all our plants need – because it always was.

And what makes this Snake Oil particularly slippery, is that there are a bunch of scientific anomalies associated with it; for example the upward movement of calcium takes place through the xylem but the downward movement also seems to take place in the xylem – there little if any lateral movement that takes place through the phloem (calcium defies the laws of nature). The mechanisms of uptake and delivery to the plant can be both passive via the intercellular spaces (the apoplast) or active through cells (the symplast). The rate of movement and pathway calcium takes seem deliberate but what triggers one direction over the other is unclear (scientists can’t explain how it works).

While there will undoubtedly be truth in the claims and capabilities of our product X and it’s scientifically formulated, patent-pending goodness [and there are several of these plant additives and supplements available] consider how many of those truths are relevant. Calcium is essential for plant growth and calcium deficiency can be disastrous, these are true statements; if your soil is lacking it then consider adding some. Calcium can be easily lost from the soil when dissolved in water (leached), or absorbed by soil organisms, so it’s worth checking for levels, but beware – too much of a good thing can be a bad thing.

So before you apply ‘X’ consider what could happen if you add calcium when it is not needed – that which doesn’t kill you, might just kill your plants. Excessive calcium may cause growth rates to slow and prevent seed from germinating. Calcium can bind to phosphorus and other nutrients so adding it may limit the availability of other nutrients. Depending on the soil type, the parent material, the amount of clay and/or organic matter there may be more than enough calcium in the soil – adding more to some soils probably will do more harm than good. The availability of calcium can be affected by periods of drought or when soil moisture is inconsistent – maybe all it needs is a good water. And if you do decide to add some (because you actually might need too), consider when – timing is everything; plants are less able to take up calcium when the soil is cold and calcium is in highest demand during periods of active growth (so maybe avoid autumn, winter, very early spring and late summer if its dry).

Everything in moderation; if it is too good to be true, or there seems to be too much true to be good then maybe its Snake Oil.

• Written for the ARB Magazine (UK)