I hear it at least once a week: “To help our British wildlife we must focus on growing native plants.” It’s evangelised on gardening TV shows, in horticultural magazines and has even found its way into planning legislation. The one problem with this ubiquitous piece of science advice is that it really isn’t very scientific, and may even hamper your attempts to support local biodiversity.
The “native is best” hypothesis rests on three basic premises: first, that British wildlife is somehow a clear-cut group that is dramatically different from wildlife abroad. Secondly, our native plants are equally unique, with highly specialised adaptations. Finally, that these highly specialised adaptations create a perfect ecological fit, which renders non-indigenous plants measurably worse sources of food and shelter for local animals.
Yet in reality, the animals of the British Isles are all relatively recent exotic introductions. They are made up of the quick-footed invaders that managed to recolonise the area in the short geological window between the glaciers of the last ice age retreating and the melting ice caps flooding the English Channel, cutting us off from the continent. Rather than being highly specialised, these invaders are often generalists, capable of living in a huge range of habitats. Many of the most famous “British” animals have native ranges that span as far afield as the Canary Islands to Siberia and North Africa to East Asia. To many of these animals, an alpine meadow or subtropical swamp is just as “native” as British oak woodland.
A great irony is that much of the current advice recommends planting flowering plants of traditional cornfields. These might strike a nostalgic chord with gardeners, they might be beautiful and they might indeed be great for wildlife. But they are also invasive arable weed species that were only brought to our shores when the first farmers decimated native forest and replaced it with wheat fields. Because defining what is truly “native” is notoriously complex and largely subjective, we simply apply the label to things we happen to find attractive and emotive, regardless of origin.
Studies consistently show that the strictly native plants are not superior food sources for wildlife. Towards the end of the season, non-natives may even prove better food sources than many British species. Discrimination on this basis is a uniquely human trait. To animals, food is food.
The majority of garden plants in the UK are an amalgamation of the flora of six continents. So there is no reason for gardeners to limit their options. Aiming for the greatest diversity of flowering species, to provide the longest season of interest, is as good for pollinators as it is for people.
Email James at james.wong@observer.co.uk or follow him on Twitter @Botanygeek
