We’re often told that native British plants are better for wildlife than cultivated plants introduced from other countries, but have you ever wondered whether anyone told the insects?
I work on plant trials at Capel Manor Gardens and last year I was recording information on a trial of native wildflowers. I noticed that some of the cultivated foreign plants we were growing in other trials were attracting at least as many insects as the natives, and often more.
I started to wonder about the advice that’s often given about the types of plants we need in our gardens if we want to provide food for insects. It’s usually suggested that native wildflowers are better than cultivated plants, especially if they’ve been introduced from other countries. Yet, from what I could see, that just didn’t seem to be the case – the plants I’d noticed being mobbed by bees were Heuchera and Penstemon, both intensively-bred North American natives.
When I looked into this further, I soon realised that there’s currently quite a lot of research being done on this very subject and even the experts concede there’s a lot we still don’t know.
Best plants for wildlife – the expert view
Plant biologist Dr Ken Thompson explains in this month’s Which? Gardening magazine that even the term ‘native’ is misleading, since after the last ice age Britain was colonised by many plants from other European countries. We also have many plant species (and insect and animal species for that matter) that are related to plants from other northern hemisphere countries to which we were physically linked to in the more distant past.
The RHS has also carried out a three year trial called ‘Plants for Pollinators’ and found that pollinating insects don’t discriminate between native and non-native plants. And its’ findings back up previous research by the University of Sussex.
Insects’ favourite flowers
Of course, there are certain types of cultivated plants that don’t suit pollinating insects, such as plants with very full double flowers where many nectaries are replaced by petals. That means it’s not a good idea to pack your garden with frilly doubles at the expense of simpler flowers, such as lavender, which we all know attracts bees.
But did you know that even among lavenders, insects have their favourite types? Lavender x intermedia has proved to be more popular than either English or French lavenders, which are much more commonly grown. In our trial garden the plant that really caught my eye was Penstemon ‘Riding Hood Lavender’, which was visited by far more bumble bees than any other plants. So far it seems no-one fully understands why insects have these preferences.
The research continues. This year we’re hoping to help the Wildlife Gardening Forum, a group of wildlife experts from various organisations, with some citizen science that’s being carried out by nearly 2,000 Which? Gardening members. They’re growing three different sunflowers, a couple of varieties that produce pollen and one bred not to produce it (for the cut flower industry). We hope to see whether or not this makes a difference to insect visitor numbers.
It’s just one small step towards providing more answers to some of these vital and complex questions. In the meantime, I’d like to know whether you’ve noticed any plants in your garden, native or not, that regularly buzz with bees or attract butterflies? Do you have a native wildflower meadow, or an area in your garden that you’ve planted up deliberately to attract pollinating insects? Is it doing its job?