Buddleja davidii is a hardy, semi-evergreen shrub with greyish-green foliage and arching cane-like branches at the end of which appear flower spikes of brilliant mauve. White cultivars are also available.
Attractive to butterflies, these flowers resemble lilac and have a light fragrance.
There is a tendency due to their fast growth to become a bit straggly, but that can be kept contained and neat with regular pruning.
Varieties include:
'Black Knight' - deep purple flowers,
"Nanho Blue" has more slender leaves than the species and bears lilac/blue flowers on narrow spikes.
'Pink Delight' - pink flowers
'Royal Red' - flower spikes of brilliant claret red
'White Profusion' white flowers with yellow eyes.