Butterfly Bush, Buddleia davidii, has been widely bashed from garden writers, ecologists, and conservationists. Attacked from all sides by master gardeners and other garden professionals, I am sticking to my guns on the benefits and pleasures of planting it. “An invasive thug that only provides sugar-water”: That is the complaint that conservationists use to discourage you from planting this shrub.
As a preferred late summer nectar source and butterfly magnet, I enthusiastically promote it in my butterfly presentations for its many virtues. An important tool to draw butterflies, I also plant many natives next to it that can act as host plants.
One of the few flowering shrubs that deer will not touch, I use it all the time in my landscape designs as an easy to grow, beautiful, fragrant, disease free, flowering shrub. The only care required is a general whacking back of the whole shrub in the early spring to encourage bushiness and flower production. Over 100 varieties provide a wide palette of forms, sizes, and colors, to choose from. The dwarf varieties are especially valuable for small gardens and containers, like ‘Blue Chip’ and ‘Pink Chip’, growing only 4 feet tall. And these are sterile varieties that will not set seed.
Why do butterflies love this plant? Providing loads of sugar water , the nectar filled nectaries, are shallow which is important to accommodate the short-tongued butterfly. Butterflies can reach the copious nectar easily which has a high percentage of sucrose, an energy fuel. Attractive to moths, bees, and other insects, this plant is valuable to all kinds of wildlife, not just butterflies.
Native to Japan and China, butterflies don’t care where their source of nectar hails from. In my post Butterfly Watching, I noted that butterflies have taste receptors on their feet to locate food and if their foot’s receptor and the molecule match, the butterfly eats. So, the plant’s origin is irrelevant and is an attractive food source. As humans, we eat many non-native plants, why can’t a butterfly do the same?
Invasive thug or non-native adaptive? There are several ways of looking at this plant. I know that it invades into mostly disturbed areas where lots of aliens/invasives have already taken over and is known as an invasive in over 25 states. But still, it is providing an important late summer source, when it is sorely needed. The other short-coming that ecologists claim is that butterfly bush only provides nectar, not acting as a host plant for the caterpillar to reproduce, but that is also true of other native plants.
Butterfly Bush seeds do not ripen until dry weather during the following spring. Worried by the potential for invasiveness? Then you can dead head it before the seeds ripen in the spring or cut the whole bush back which will eliminate the spread of seeds into adjacent habitat. Colonizing disturbed ground sites such as railway lines, quarries, roadsides and waste ground, butterfly bush can form dense stands of shrubs that butterflies flock to. What’s not to like!? Here is the position of the UK’s Butterfly Conservation on their website:
“Buddleia provides an important nectar source for adult butterflies, moths and other insects in townscapes and the countryside. This has become increasingly relevant because wildflowers have become so depleted following habitat loss and the general lack of nectar sources in the countryside. It also brings enjoyment to many people, both because of its heavy-scented and beautiful blooms but also because of the butterflies and other insects it attracts. It therefore plays a role, alongside other non-native garden plants, in helping to maintain or restore the link between people and native UK wildlife such as butterflies. In gardens, Buddleia is often pruned annually thus removing seed-heads and reducing the potential for seeding.
Buddleia is not important as a caterpillar food-plant and cannot replace naturally occurring wildflowers, which are crucial to provide a variety of nectar through the year as well as being food-plants for caterpillars. Buddleia can cause serious problems on some important conservation sites, especially brownfield sites. It needs to be controlled in these and other semi-natural sites to allow natural vegetation to develop. The cost of control can sometimes be considerable.
In reaching a position on Buddleia it is important to weigh up the undoubted benefits it brings in garden situations against the possible risks to wildlife habitats. It is also important to recognise that Buddleia is already naturalised and well established across much of the UK.
In view of its value as a nectar source, BC will continue to recommend its planting in gardens alongside other butterfly-friendly non-native plants, but will avoid giving it undue prominence and will give advice on its management and control.
A sea change is going on with some conservationists, that we are dealing with a changed world and there is no way to go back to an idealized world of stable co-habitating species. From the beginning of time, species have moved around, finding new territories, and creating new ecological niches. Invasive species, like it or not, are part of nature. Serving an ecological purpose, whether it aligns with our idea of what it should look like, isn’t relevant to nature.
And according to the Royal Horticultural Society:
• Research reveals a mixture of native and non-native ornamental plants may provide the best resources for pollinating insects in gardens
• Native plants are not always the first choice for pollinators visiting gardens
• Non-native plants can prolong the flowering season providing an additional food source.
So, armed with this knowledge, you make the decision.