Buddleia davidii. Photo by tijmenkroes

Buddleia is a common-as-muck garden shrub. But it doesn’t consider itself just a garden shrub. Stare out of any train window and you will see miles of purple spires running alongside the track as the thuggish Buddleja davidii scrambles for more and more space. Ask anyone who maintains railway tracks about Buddleia and they will screw up their face in disgust and denounce the opportunistic invader.

But, like a naughty child, Buddleia manages time and time again to evade widespread hatred. It is too sweet-scented, too encrusted with butterflies and altogether too beautiful.

And it’s also a very varied species; far more varied than most imagine. The lilac panicles of the ubiquitous Buddleja davidii are by far the least exciting. Many readers may not even know that B.davidii also has cultivars flowering in many other shades – most of which are not invasive. There is the velvety ‘Black Knight’, or the bubblegum ‘Pink Delight’. There are white, red-purple and variegated cultivars of B.davidii.

But the species has far more to offer than the common garden B.davidii. There are around 100 known species of Buddleja, hailing from Asia, the Americas and Africa, ranging from deciduous to everygreen, and growing up to 30m.

Another popular cultivar is B.globosa, or ‘Orange Ball Tree’. Walk past this evergreen bush when its orange baubles are flowering and you’ll find yourself drinking in its heady honey scent. You won’t be the only one to stop and sniff. Like all buddleias, B.globosa is extremely popular with beneficial insects such as butterflies and bees. 

Buddleia globosa. Photo by magda.indigo

Many buddleia require careful pruning to prevent them from becoming scrawny, but one very elegant type is B.alternifolia, which produces long weeping branches covered in purple flowers.

One of the most striking is B. x weyeriana, which produces loose, globular clusters of golden flowers. Some rather ethereal-looking types are lilac-edged with orange throats.

Buddleias are very content shrubs, and make little complaint wherever you plant them. But if you want your butterfly bush to perform to its best, then plant it in full sunlight in rich, deep soil. Place larger cultivars at the back of the border, and mulch in the autumn.

Prune B.davidii in March, and make sure you give it a good firm haircut, snipping off growth back to the second set of leaves. Flowers will be larger and more prolific on new wood for this species, so don’t be afraid to be enthusiastic.

For types such as B.alternifolia, B.asiaticia, B.globosa and B.colvilei, which bloom on last year’s wood, however, you must wait until the flowers have died in late summer before you start brandishing the secateurs.

Visit Longstock Park Nursery, the holder of the National Collection of Buddleia for a wide range of cultivars and expert growing advice.