Fragrant Summer Lilac - Buddleja davidii 'Empire Blue' (Butterfly Bush)

Buddleja davidii 'Empire Blue' is a variety of ornamental shrub in the Scrophulariaceae family, popularly known as the "butterfly bush". This plant is valued for its spectacular and fragrant flowers, which attract butterflies, bees and other pollinating insects, making it an excellent choice for gardens that want to support biodiversity.

Flower appearance

• Shape : The flowers are small, tubular, grouped in long, dense panicles (large clusters) , which can reach 20-25 cm in length . They are arranged at the ends of the branches, creating an impressive visual effect and are large producers of nectar - a real attraction for bees and butterflies .
• Color : They are a deep shade of intense blue-purple (sometimes described as a true blue), with a small orange "eye" in the center of each flower, providing a subtle but attractive contrast.
• Fragrance : It exudes a sweet, fruity fragrance , which enhances its attractiveness to pollinators and adds a pleasant touch to the garden.
• Flowering period : Blooms profusely from June to October , sometimes until the first frost, especially if wilted flowers are removed regularly (deadheading), which stimulates continuous flowering.

Growth characteristics

• Height : It grows compactly, reaching a height of 1.5-2 meters and a similar width, making it smaller and easier to integrate into gardens than other varieties of Buddleja davidii.
• Foliage : The leaves are lanceolate, silvery-gray green , with a fine texture and a slightly downy appearance on the back. They are arranged oppositely on the branches and provide an elegant backdrop for the vibrant flowers.
• Vigor : It is a fast-growing shrub, but remains well-proportioned, with arching branches that give it a graceful and airy shape.

Growing conditions

• Exposure : Prefers full sun for abundant flowering, but also tolerates semi-shade , although with fewer flowers.
• Soil : It needs a well-drained soil, from average to fertile, and adapts to various types (clayey, sandy), provided that the water does not stagnate. It tolerates a variable pH (acidic, neutral or alkaline).
• Watering : Requires moderate watering; is relatively drought tolerant once established, but its performance declines in conditions of excessive moisture.
• Pruning : A severe pruning is recommended in February-March , to 15-30 cm above the ground, to encourage vigorous growth and abundant flowering on new wood. Removing faded flowers during the season prolongs flowering. This pruning also serves to delay flowering, reducing the risk of the plant being affected by late frosts.

Care and resistance

• Hardiness : It is hardy to -20°C (USDA zones 5-9), but in colder climates it may die back to the ground in winter, behaving like a herbaceous perennial. In spring, it begins to grow vigorously again from the roots.
• Fertilization : A balanced fertilizer applied in spring supports flowering, but is not strictly necessary in fertile soils.
• Pests and diseases : May be affected by aphids, mites, or mullein moth, but is generally resistant if well ventilated. May develop mold in wet, poorly drained conditions.

Garden use

Buddleja 'Empire Blue' is ideal for borders, cottage gardens, or as a solitary plant in mixed landscapes. Due to its compact size, it also fits in containers on terraces or balconies. Its blue-purple flowers combine beautifully with yellow (e.g. Kniphofia) or white (e.g. white roses) plants, creating vibrant contrasts. It is also excellent as a cut flower, due to its fragrance and durability.

Origin

Buddleja davidii is native to China and Japan , where it grows naturally on rocky slopes and in disturbed areas. The variety 'Empire Blue' was developed in Britain in the 20th century as part of horticultural selections designed to enhance the plant's intense colors and hardiness. Although there are no precise details about the exact year or breeder, 'Empire Blue' is one of the first varieties to popularize shades of true blue in Buddleja culture, being prized by gardeners for its color and reliability.