With such a wholesome image, the world of horticulture can have some surprisingly passionate debates. So while it is probably extremely unwise, I thought I would wade into one of the most heated questions in gardening in recent years: should you really water tropical orchids with ice cubes? Bear with me鈥�
I first came across this idea over a decade ago at a horticultural trade fair in the Netherlands, where giant commercial orchid growers were unveiling a glossy new campaign. Oversized retro fridges and fake ice sculptures were festooned with live orchids, under a neon cocktail bar sign that said 鈥淛ust Add Ice鈥�. Aware that one of the most common reasons for beginners to fail when growing moth orchids (Phaleanopsis) is overwatering, nurseries were advising that adding three ice cubes to a plant each week was an easy way to provide a measured dose of water, released slowly as the ice melts.
However, moth orchids (pictured above) are tropical plants that don鈥檛 possess adaptations to help them survive sub-zero temperatures. So: cue a furious online backlash from the orchid-growing community (yes, there is one), who say this advice would cause crippling damage to these delicate plants that would far exceed any of its supposed benefits. And yet, many years later, the campaign still endures, as does the fiery controversy. So what does the evidence actually say?
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Considering how long this argument has been raging, it is surprising that only one published scientific trial seems to exist. And even to a botanist like me, its results were unexpected.
Researchers flowering moth orchids watered with ice to a control group given an identical volume of water. It was a well-designed experiment too, using multiple cultivars, two different test locations and a decent number of subjects. What it found is that, perhaps counterintuitively, the ice had no measurable effect on how long the flowers lasted, nor how well their leaves or roots grew 鈥� a set of findings the 鈥淛ust Add Ice鈥� campaign is keen to publicise.
I would point out that the trial only lasted for a few months, from the day of purchase until the flowers faded. As orchid growth is comparatively slow, this is really a very short snapshot of time, and gives us no indication as to how it may effect reflowering. Not to mention that, as it was just a single trial, we have no idea whether the results are replicable. Most importantly, while it didn鈥檛 seem to harm plant growth in the short term, the ice didn鈥檛 seem to actually have any benefits either.
The bottom line? The evidence so far suggests we have been making a bit of a fuss about nothing. Right now, it seems you can do whichever you find easiest, without any clear consequences. So let鈥檚 put the pitchforks down.
James Wong is a botanist and science writer, with a particular interest in food crops, conservation and the environment. Trained at the Royal Botanic Gardens, Kew, in London, he shares his tiny flat with more than 500 houseplants. You can follow him on X and Instagram @botanygeek
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