30 October 2014
Buddleia davidii - or 'butterfly bush' - is great at attracting various insects to feed on its nectar. This is why it has been planted widely in wildlife-friendly gardens and other open spaces, after being introduced from China.
Why can Buddleia davidii be bad?
It has become increasingly clear that Buddleia davidii can be highly invasive. It produces lots of small, light seeds, which spread extremely easily. It can grow in many places, even in cracks in buildings several floors up.
Buddleia davidii can form thickets in places like disused industrial sites and railway sidings, and natural habitats like chalk grassland. These places support a large number of invertebrate species, some of which are rare and endangered. B. davidii can quickly cover open ground – which means those special species can no longer live there.
But it's so good for butterflies!
Yes, Buddleia davidii can attract many butterflies, but if it is at the expense of rare invertebrates that would otherwise be living there, it is preferable to plant non-invasive flowers for the butterflies to nectar at.
What can I do if I have Buddleia davidii in the garden?
If you like your Buddleia davidii, you don’t have to remove it. But prune it severely as soon as the flowers have faded – that means it doesn't have a chance to spread its seeds. Remember to dispose of the prunings properly, not by dumping them over the garden fence. And when your B. davidii dies, consider replacing it with non-invasive shrubs.
What can I plant instead?
There are actually some Buddleias that are not thought to be invasive. Try Buddleia x weyeriana, which has yellow flowers which are sterile and won't set seed. There are plenty of alternative shrubs to choose from – these are all attractive garden shrubs and aren't invasive:
- Heathers (good for butterflies)
- lavender (good for butterflies)
- currants (Rubus)
Are there any other shrubs I should avoid?
Buddleia davidii is not the only shrub that has turned out to be invasive. Many of the species of cotoneaster available in garden centres are highly invasive - some so much so that it is now illegal to plant them in the countryside or to allow them to 'escape' from your garden!
Other invasive shrubs include Rhododendron ponticum, cherry laurel and snowberry. Some non-native honeysuckles are invasive, and you even need to be careful with what roses you plant – Rosa rugosa is among the worst invasives we should not let out of our gardens.