The science of gardening | Financial Times

Science and gardening are bedfellows, but not as snug as they should be. Gardeners appeal for scientific advice when yet another family of plants begins to look sick and die. Otherwise they tend to follow practical experience, believing that if something has worked before, it will work again. When a problem occurs, they flick around online. Online scientific dogma includes pseudoscience, so I am wary of it.

My impression is that science and gardeners are now in more of an embrace. One good reason is that the changing climate has brought them together. Science is also more prominent in schedules on BBC Radio 4, to which many of us listen during work outdoors.

Naturally the FT was there first. When I started to write for it in 1970, my senior partner was the great Arthur Hellyer, who had shown a scientific turn of mind already as a schoolboy at south London’s Dulwich College. He applied it to gardening when an early attack of TB obliged him to work in the fresh air. His guides to gardening are still notable for the clarity of their scientific approach, though their chemical advice has sometimes been corrected by further study. I try to honour his approach.

At its headquarters, the Royal Horticultural Society has also given momentum to the shift. Its scientific section at Wisley in Surrey used to bump along in old-fashioned buildings and be off limits for most visitors to the garden. The Laboratory building, upgraded, will be opening next month as a new exhibition space but meanwhile science has a shining new Wisley centre and a funded prominence in the RHS’s work.

In 2013, its director-general Sue Biggs turned to John Parker, best known for previously heading the Cambridge University Botanic Garden, and invited him to advise on future directions that the RHS and its Wisley garden might take. Botanic gardens are interlinked with science, so it was no surprise when Parker, the former head of one, stressed the scope for more science.

Botanic gardens with university links support plant sciences, usually the rarefied study of cells and genes. Taxonomy, the correct ordering and naming of plants, is sadly less of a priority. I am often surprised how great plant scientists know next to nothing about plants in the wild, in the round or in a garden: we sing from very different hymn sheets. Horticultural science is a closed book to them, so Biggs and the RHS saw scope for helping to fill a gap. Science also opens the possibility of big public grants, a process CEOs like to head. Grants start a snowball which private trusts and donors are more likely to join. The result is a measurable legacy.

Slug research at the centre
Slug research at the centre © RHS/Arnhel de Serra

Ten years on, I have just been to Wisley to see how science now fits in. The RHS’s director of science Alistair Griffiths explained to me the current scope of the programme, from wildlife to carbon to gardeners’ psychology and much else. For the newly built Hilltop scientific centre, Biggs and her team raised £35mn, a fine achievement. An annual scientific budget of £1.1mn in 2013 has grown to £6mn and, by forging links across other UK universities, now supports a staff of 124, including scientists who co-supervise a cluster of doctoral students. Some of it is funded from an endowment, but most of it comes from profits from the RHS’s hyper-activities.

Since the mid-1990s, I have watched the RHS take on corporate values and strategies like a start-up on steroids. Those flashing icons on its website, telling browsers to Join the RHS Now, are a bit much for visiting parasites like me who simply want to know where to find a plant in a British nursery. If they join however, some of their subscription goes to help the enlarged scientific mission.

The new centre at Wisley is a major presence. An airy atrium welcomes visitors with uplifting storyboards about helping the wellbeing not just of mind and body but soul too, an entity the writers evidently believe in. Online interactivity is available, but on the first and upper floors I was able to visit the scientific heart, the reserved space for the RHS’s herbarium and the open-plan rooms for researchers on screens, studying anything from peat alternatives to pollinators.

The head of the herbarium showed me a great treat, a bit of a Chilean potato, carefully pressed and preserved, which Darwin brought back from his voyage on the Beagle: it was later bequeathed to the RHS.

In the science rooms, I enjoyed a chat with the lead researcher into honey fungus, a big subject of RHS study and a concern for gardeners who plant for decades in one and the same place: it kills trees and shrubs. A dose of Armillatox used to be the way to kill it, but Armillatox is now known to destroy the microbial structure of the soil: it has been withdrawn. Honey funguses are also now known to come in many shapes and sizes: the best way to contain the killers is to dig them out along their entire length.

Hedging plants are also being studied, especially for their ability to capture carbon in urban sites. On other grounds I have long favoured the grey-leaved Cotoneaster franchetii in this column, but it turns out to be a good carbon-captor too, thanks to the tiny hairs on its leaves. Smooth-leaved Photinia Red Robin turns out to be ineffective: this sort of evidence-based research has a future.

Other choices in other research categories are less persuasive: is a holly tree really one of the best choices for a small garden? It has berries for birds but so do maluses and sorbuses. Unlike them, it has horribly prickly leaves.

What about wildlife and gardeners’ own wellbeing? RHS questionnaires have tried to monitor and quantify the contribution gardening may or may not make to individuals’ wellbeing. By analysing the levels of cortisol in our saliva, researchers believe they can map our levels of personal satisfaction. I can well believe that a planting in a front garden may add to house-owners’ contentment, but I am sceptical of attempts to quantify qualities as subtle as happiness. I would rather know how best to kill slugs.

The RHS is active here too despite its general slogan about “gardening for wildlife”. Slug research has already revealed unexpected complexity. There are slugs in compost heaps that are beneficial to gardens, the yellow cellar slugs with a long yellow stripe down their thin bodies being examples. The way to treat slugs is no longer to kill them all on sight. Thank you, scientists, and I wait for more lessons to come.

Meanwhile I continue to squash the big black plant-hungry slugs that slime into my kitchen and head for any salads and seedlings within reach.

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