Slugs have feelings too

There is a contradiction at the heart of wildlife gardening which, like some awful relative you hope will never visit, is never mentioned but always lurking at the back of your mind. This is that there is good wildlife and bad wildlife.

To try to illustrate what I mean, let’s look at a recent initiative by Natural Resources Wales (NRW), one of the three British government national conservation agencies. In an entirely admirable attempt to end some of the confusion about which plants should be grown by wildlife gardeners, they have attempted to produce a definitive list of wildlife-friendly garden plants. It’s a good list, and the wildlife in your garden would undoubtedly benefit if you grew a selection of the plants on it.

The really interesting thing, however, is why these 174 plants are recommended. Because some plants are recommended for more than one reason, the list actually contains a total of 276 different ‘plant/reason’ combinations. Forty-six of these concern birds and are nearly all plants with berries. Virtually all the remaining recommendations (211 out of 230) involve flowers for pollinators, in the following order: bees, butterflies, other insects, hoverflies, moths. This list therefore reflects two things – first, that gardeners like pollinators, especially bees and butterflies, and second, that the ecology of pollination is reasonably well understood.

So far so good, but consider hoverflies – large, harmless, attractive, often brightly-coloured insects, and good pollinators. Just the sort of thing you want in your garden. Oh, and even better, the larvae of many species eat aphids. But there’s a snag here - in providing lots of flowers, you are catering only for adult hoverflies. Hoverfly larvae need lots of aphids, so shouldn’t you be providing them too? In fact aphids are the garden equivalent of krill – small, extremely abundant, and the base of a whole ecosystem of predators and parasitoids. To take another example, there are 14 recommendations in the NRW list of plants for moths, eight of them for flowers and six as larval food plants. Six? There are 886 species of large moths in Britain!

To summarise the problem: first, at the base of all food chains are animals that eat plants, but few gardeners would willingly grow plants that could be relied on to have half their leaves devoured by caterpillars, with the remainder infested with aphids. On the contrary, if we knew a plant that would kill stone dead any aphid or caterpillar that touched it, many of us would probably grow it with only a twinge of regret. Second, the ecology of garden plants is generally so poorly understood, that even if you wanted to grow plants that were attacked by a wide range of herbivores, you probably wouldn’t know where to start.

The real paradox in recommending pollinator-friendly garden plants is that with a few exceptions (some modern cultivars, and wind-pollinated plants like grasses), all garden plants are at least moderately useful to pollinating insects. One symptom of this is that while the NRW list is one of the best of its kind, I’m sure we all have favourite bee or butterfly plants in our own gardens that are not on it. And although I fully understand why buddleja continues to appear on lists of plants for butterflies, can there be a single gardener left with even the slightest interest in wildlife who doesn’t already grow it?

So, before you embark on wildlife gardening, some serious self-examination is in order. Growing the plants on the NRW list will do for starters, but real wildlife gardening is less about what you grow than about how you grow it. You’ll know you’re a real wildlife gardener when you can agree with Jennifer Owen, even if through gritted teeth: “There are no pests, because everything in my garden is a source of interest and enjoyment”.

This is a (slightly edited) extract from Ken Thompson’s first book, “An Ear to the Ground: Understanding Your Garden”. Ken is a plant biologist with a keen interest in the science of gardening. He writes and lectures extensively and has written five gardening books, including “Compost: The natural way to make food for your garden”” and “No Nettles Required”. His latest book is “The Sceptical Gardener”. Ken is also a trustee of the Wildlife Gardening Forum.