Sandy’s Garden ... Do plants talk?

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A budgie used to share our home. Unlike most budgies, he was not a caged bird: he was a free spirit, given the run of our house. Before you ask, he house-trained himself, always returning to his ‘home’ … his cage, though we never used that word in his presence … to ‘do his business’. He never ‘spoke’ as many budgies do, replicating the sound of the human voice with a greater or lesser degree of accuracy. But he did try desperately hard to communicate with us; and he would stamp his foot in sheer frustration when he simply could NOT get us to understand the message he was trying to convey.

What prompts this thought is the recent claim that researchers have proof that plants talk to one another. “Having a neighbourly chat improves seed germination,” was the claim made in BioMed Central’s open access journal BMC Ecology. “Even when other known means of communication, such as contact, chemical and light-mediated signals are blocked, chilli seeds grow better when grown with basil plants. This suggests that plants are talking via nanomechanical vibrations.” The words ‘chat’ and ‘talking’ were seized upon with interest by some sections of the media, an outcome which was surely the intended purpose of their use.

But the original press release was more guarded. “Monica Gagliano and Michael Renton from the University of Western Australia attempted to grow chilli seeds (Capsicum annuum) in the presence or absence of other chilli plants, or basil (Ocimum basilicum),” it states. “In the absence of a neighbouring plant, germination rates were very low, but when the plants were able to openly communicate with the seeds more seedlings grew. However when the seeds were separated from the basil plants with black plastic, so that they could not be influenced by either light or chemical signals, they germinated as though they could still communicate with the basil.”

Dr Gagliano explained, “Our results show that plants are able to positively influence growth of seeds by some as yet unknown mechanism. Bad neighbours, such as fennel, prevent chilli seed germination in the same way. We believe that the answer may involve acoustic signals generated using nanomechanical oscillations from inside the cell which allow rapid communication between nearby plants.” The relevant words here are ‘communicate’ and ‘acoustic signals’. And fennel is well-known as a neighbour from hell in the plant world.

Keen gardeners have known for years about a phenomenon known as ‘companion gardening.’ Carrots are tastier, crunchier and more brightly coloured if they are interplanted with leeks; rosemary is an excellent neighbour for cabbage, its scent repelling insect pests, a characteristic that can be employed to good effect almost anywhere in the garden; garlic and roses do well together for the same reason; and chives grown in the rose-bed are another effective insect repellent, especially if the gardener trims them regularly to encourage the release of their scent. As far as I am aware, there is no definitive answer as to why some companion plantings work – excluding the obvious emission of insect-repellent scent. Deep-rooted plants are known to draw up traces of mineral elements which then benefit shallow-rooted neighbours … dandelions being a good, if unpopular with gardeners, example. Equally obviously, shade-loving plants enjoy growing beside neighbours which provide shade; and many plants benefit from being grown with brightly-coloured or strongly-scented flowers that attract bees to their locality. But ‘talking’ to one another? I think that’s an overstatement.

Sandy Simpson, Polmont Horticultural Society