- Position: full sun or partial shade
- Soil: fertile, well-drained soil
- Rate of growth: fast-growing
- Flowering period: July to September
- Hardiness: fully hardy
Much maligned for its habit of colonising railway sidings, buddleja can be a fabulous addition to a sunny border, with dramatic, fragrant flowers that are attractive to butterflies and other beneficial insects. Pruned hard in spring, 'Black Knight' produces dense spikes of tiny, fragrant, dark purple flowers. In autumn the pointed grey-green leaves turn butter-yellow. Deadheading the buddleja will encourage it to produce more flowers and stop any unwanted seedlings.
- Garden care: Prune back hard in March, removing all of the previous year's growth to three or four buds.