There is a lot of press out there telling us that if we want to support and encourage wildlife in our gardens, allotments, parks and hedgerows, we must stick to species that are indigenous to this country. At face value this makes perfect sense. The wildlife that has evolved in any given area has evolved alongside certain plants so it should follow that native plants need native pollinators,  and native invertebrates – bees or butterflies, for instance – prefer native plants to feed from. It all seems to fit together nicely but is it backed up by science?

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Some plant and animal species do indeed evolve to be mutually reliant and in these cases no other plant or animal will do as a substitute. The Large Blue butterfly can only breed in partnership with a species of Myrmica red ant together with the wild thyme, Thymus polytrichus, and because of the decline in habitats that supported both the ants and the thyme, the Large Blue was threatened with extinction in Britain until the relationship was discovered and efforts made to protect the appropriate habitats. However, this sort of critical relationship is rare and most species of wildlife have evolved to be able to take advantage of a wider variety of ecological niches; the vast majority of herbivorous species of British wildlife can feed off a number of plants as both adults and young. Seed eaters, both birds and mammals, don’t rely on just one species of plant seed to keep them going, and most British butterflies don’t rely on just one plant to feed on or on which to lay their eggs. There are always specialist feeders and breeders and those must always be considered, but as a whole a garden planted with a variety of plants that are accessible to a large number of species will do the most good. But do these plants have to be natives?

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First of all we need to know what is meant by ‘native’ and ‘non-native’ and we need to know what we mean by ‘wildlife’. Native, in this context,  is any plant or animal which has established itself in Britain since the last Ice Age without anthropogenic activity, or in other words, which has got here with no help from humans.

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There is a certain amount of bias in these discussions and people -  laymen and experts - have their own favourites when it comes to promoting and preserving ‘wildlife’. I recently read an article about the relative merits of the advice doled out by the gardening and popular press with regards to gardening with bees in mind, and among its recommendations was to ignore advice about leaving a patch of lawn to grow long because, the article stated, while clover is an excellent food source, the number of clover flowers you could get in a patch of long grass is far less than the number of other nectar-rich flowers you could get if you turned that patch over to a flower garden. While this is very true,  this sort of narrow view ignores the fact that the long grass also provides cover and food for other animals – mammals, invertebrates, amphibians and reptiles; that many species of solitary bee and  bumble bee nest in tangles of long grass; that many species of British butterflies need long grass as egg laying sites and that the presence of a healthy population of invertebrates and mammals will encourage birds, reptiles and amphibians and all these garden visitors will make pest control in the garden much easier for the gardener and much healthier for the environment. The garden food web is extensive and complex.

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 When we say Wildlife, we tend to say it with a capital ‘W’. Are we only talking about invertebrates, and if so, which ones? Bees, ants, springtails, butterflies, beetles, spiders or something else?  If we qualify our choice of invertebrates and say bees, just what kind of bee do we mean: honey bees, solitary bees or bumble bees – and which species, because each species have vastly different breeding, nesting and feeding needs.  Do we include mammals in this discussion and if so, which kind: squirrels, bats, foxes, mice or shrews?  You get the picture.

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So if we are all clear about what we mean by native and by wildlife (even if my ‘wildlife’ is different to yours) are we to agreed that native plants are the best things to support native wildlife?

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Luckily RHS Wisely, the great horticultural research station near London, has recently  concluded a four year study conducting tests on just this topic to see if they can get to the bottom of this great wildlife and gardening debate. Over four years they maintained 36 beds of plants, 12 full of native plants, 12 full of near-natives (plants from the Northern hemisphere excluding Britain) and 12 full of exotics (plants that originate only in the Southern hemisphere).  Each bed contained a mix of 14 species of plants, including bulbs, perennials, shrubs, grasses, ferns and a climber in order to  mimic a typical small garden border. The emphasis in this study was on pollinating insects but flying, crawling, creeping and soil born insects were also methodically sampled and the conclusions were clear; to encourage a large number and range of wildlife species, plant a large number and range of plants on which they can feed and breed. The origin of the plants was minimal importance compared to the numbers and suitability of the flowers.

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My own go-to example for this is the wall shrub, Cotoneaster horizontalis. I have one by my garden gate which grows over a Cotswold stone wall and up and over my garage. It can be an untidy beast, but I cannot cut it down because it provides many weeks of nourishment for a huge range of hoverflies, bees, and wasps. Last week I took a couple of minutes to count the number of different species that were busy feeding on this plant and I counted 9 species of bee, hoverfly and wasp in just two minutes. The noise of the foraging insects has to be heard to be believed -   and this mass of nectar-  and pollen-rich flowers is only the beginning. The attractive herringbone branches of this plant are, in autumn and winter, studded with huge numbers of red berries that provide a feast for winter birds.   No doubt you’ll already have guessed that this Cotoneaster isn’t native to the Uk, having been introduced from China by early plant hunters and deserves no place in native-only wildlife garden, however it would be hard to find a similar sized native shrub that provides quite the same appeal to native wildlife. It is hugely important in supporting invertebrate and bird populations across the UK. On the opposite side of the argument is the fact that this and other cotoneasters are listed as non-native invasive species precisely because they are so popular with birds;  birds very efficiently spread the  seeds around the country in their droppings. However brambles, bracken and ivy are native to the British Isles and they are the three most endemic land plant pests in the UK., threatening more land and negatively altering more habitats than any non-native invader!  That isn’t to say that we should allow any plant, native or introduced, to become a pest, just that we should not judge them primarily on the whether or not they are native to these shores.

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The question in sorting out any puzzle is always ‘What are we trying to achieve?’ and if the answer in this case is to promote the use of native plant species in the garden, then by all means plant a Native Garden.  It would be a challenging project because it would be tricky to track down the true origin of many species, but it would be fascinating and I would, if I had the space, design and plant just such a garden.

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If, though, the purpose is to plant a garden which is beautiful and useful and provides maximum benefit to wildlife, then the way to go is to choose a variety of plants from any corner of the globe, with an emphasis on single or loosely semi-double flowers which flower over a long season and mix them together with grasses and berry- and seed-producing plants. Monocultures can support large populations of single species, but a polyculture (the cultivation of a mixture of plants and/or animals) leads to much greater biodiversity and you will be responsible for supporting a much larger range of British wildlife.

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• The bottom line in gardening with wildlife in mind is to provide a range of feeding and breeding opportunities by planting a range of plant species which provide interest over four seasons. If we can include some rare or native plants in the mix, so much the better for those plants, but not necessarily for the larger food web.

• If you have a particular interest in a particular species – in a butterfly for  instance, or a desire to encourage the return of a locally rare native bee - why not include a targeted corner of your garden with plants chosen specifically to support your chosen species.

• The most common buddleia species, Buddleia davidii,  was introduced to the UK from China in 1896, so it would be listed as a non-native species, but buddleia is, of course, one of the very best nectaring sources for butterflies and bees and is a great winter food source for several species of seed-eating birds as well.

• Double and semi-double flowers no longer produce nectar in the same quantities as their single versions (if at all)as the stamens have been transformed into extra petals. Similarly plants bred for the cut flower trade have had their pollen bearing ability bred out so that the flowers last longer.  Always choose single cultivars over doubles when choosing plants with wildlife in mind.