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Buddleja davidii 'Empire Blue'
Shrub
Plant Highlights: Deep violet-blue flower spikes • Long flowering season • Lightly honey-scented blooms • Excellent for butterflies and bees • Vigorous deciduous shrub
Buddleja davidii 'Empire Blue' is a vigorous deciduous shrub grown for its elegant, arching clusters of deep violet-blue flowers that appear from mid-summer into early autumn. The lightly honey-scented blooms are rich in nectar and are especially attractive to butterflies, bees and other beneficial pollinating insects, making this one of the finest shrubs for wildlife-friendly gardens.
Its graceful arching habit, grey-green foliage and long flowering period make 'Empire Blue' an excellent choice for adding height and colour to sunny borders. It combines beautifully with ornamental grasses, late-flowering perennials and other cottage garden favourites, providing reliable interest well into the season.
| Attribute | Information |
|---|---|
| Botanical Name | Buddleja davidii 'Empire Blue' |
| Common Name | Butterfly Bush |
| Plant Type | Deciduous flowering shrub |
| Foliage | Grey-green, lance-shaped leaves |
| Flowers | Deep violet-blue flower panicles with a light honey fragrance |
| Flowering Period | July to September |
| Growth Habit | Upright with gracefully arching branches |
| Position | Full sun |
| Soil | Fertile, well-drained soil |
| Mature Height | Approximately 2–3m |
| Mature Spread | Approximately 2–3m |
| Hardiness | Hardy in most Irish gardens once established |
Plant in a sunny, open position where it will receive at least six hours of direct sunlight each day. Full sun promotes the strongest flowering and helps maintain a balanced, compact habit.
Water regularly during the first growing season while establishing. Mature plants are relatively drought tolerant but benefit from occasional deep watering during prolonged dry spells, especially if grown in containers.
Grow in fertile, well-drained soil. If planting in heavy clay, improve drainage with organic matter to help prevent waterlogging during wet Irish winters.
Well suited to gardens throughout Ireland once established. Young plants benefit from good drainage during their first winters, while container-grown specimens should be protected during extended periods of severe frost.
Prune hard in early spring before new growth begins, reducing stems to around 30–60cm above ground level. Remove faded flower spikes throughout summer to encourage continued flowering and keep the shrub looking its best.
'Empire Blue' flowers on the current season's growth, so annual spring pruning encourages vigorous new stems and the most abundant display of flowers.

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