Butterfly Bush 'Black Knight' (Buddleja davidii 'Black Knight')

Butterfly Bush 'Black Knight'

Buddleja davidii 'Black Knight'

Deep purple blooms draw fluttering pollinators like living jewels. Deciduous flowering shrub; common name: summer lilac.

Full sun
1–2/week
Beginner
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Plant Needs

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Sunlight Full sun to partial shade; thrives in bright, direct sunlight for most of the day to maximize blooming
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Watering Water deeply when the top 5–7 cm of soil is dry; tolerate mild drought once fully established
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Temperature Hardy to -15°C; withstands hot summer temperatures up to 35°C; protect young plants from extreme frost
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Characteristics

  • Leaf: Lance-shaped, gray-green, fuzzy undersides, opposite arrangement
  • Flower: Dense, elongated panicles of deep violet-black, fragrant blooms
  • Stem: Woody, gray-brown, upright branching structure
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Care Guide

Watering

Water regularly during active growth to keep soil consistently moist but not waterlogged

Fertilization

Apply balanced slow-release fertilizer once at the start of growth. Use a low-nitrogen fertilizer to prioritize flower production over foliage growth

Banana peel compost tea:Compost banana peels for 2–3 weeks, steep in water for 24 hours, dilute 1:20 for root drench to support flower development; avoid raw peels to prevent pest attraction
Pruning
  • Prune back to 30–60 cm in late winter to encourage dense, vigorous new growth
  • Deadhead spent blooms regularly to extend the flowering period into early autumn
  • Remove weak or damaged branches to improve airflow and maintain a compact shape
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA confirmed non-toxic to cats; no reported toxicity

Humans: Non-toxic to humans; no known adverse health effects from ingestion or contact

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Garden Uses & Culture

Culture: Symbolizes summer joy and pollinator support; popular in wildlife-friendly gardens

Usage: Ornamental garden shrub; attracts butterflies, bees, and hummingbirds