Black Knight Butterfly Bush
Deep purple blooms, easy to grow, butterflies included
About Black Knight Butterfly Bush
Black Knight Butterfly Bush is a fast-growing deciduous shrub loved for its deep violet-purple flower spikes that bloom reliably from early summer through fall. The honey-scented blooms attract butterflies, bees, and hummingbirds, making it a natural centerpiece in pollinator gardens and mixed borders. It's vigorous, floriferous, and rewards pruning with fuller growth.
This site guides you through planting Black Knight Butterfly Bush in full sun and well-drained soil, managing its water needs as it establishes, and the spring pruning that keeps it full and floriferous. We cover seasonal care, common issues like powdery mildew, design approaches for borders and pollinator spaces, and tips for selecting healthy plants. Everything you need to grow this butterfly magnet well.
Buy Black Knight Butterfly Bush
Nursery-grown plants shipped in their container, with our planting and care guides to go with them.
From $49.49
Sizes: Quart Plant, 3 Gallon Plant
Shop Black Knight Butterfly BushQuick facts
- USDA zones
- 5-9
- Mature height
- 6-10 ft (often smaller if cut back hard each spring)
- Mature width
- 4-8 ft
- Sun
- full sun, at least 6-8 hours daily for best flowering
- Water
- moderate water to establish; drought tolerant once rooted in
- Bloom time
- summer through early fall (roughly June-September, later in warmer zones)
- Bloom color
- deep purple with a near-black cast in bud, opening to dark violet-purple with an orange ey
- Growth rate
- fast, roughly 3-5 ft of new growth per year since it blooms on new wood and is usually cut
- Deer resistance
- good/generally resistant, though not deer-proof
- Plant type
- deciduous shrub
- Deep violet-purple, honey-scented flower spikes bloom summer into fall
- A magnet for butterflies, bees, and hummingbirds
- Fast grower, reaching 6-10 ft tall and wide in a season or two
- Blooms on new wood, so hard spring pruning keeps it full and floriferous
- Thrives in full sun and well-drained soil; very drought tolerant once established
- Hardy in USDA zones 5-9; may die back to the ground in colder parts of that range
- Regulated as invasive in some Pacific Northwest states, so check local rules
Growing guides
Core guideThe Complete Black Knight Butterfly Bush Care Guide
Learn how to care for Black Knight Butterfly Bush. Zones 5-9 planting, pruning, watering schedule, and expert tips for maximum blooms.
Core guideHow to Plant a Black Knight Butterfly Bush the Right Way
Learn how to plant Black Knight Butterfly Bush with step-by-step instructions, timing, spacing, and soil prep for thriving gardens.
Core guideWhen and How to Prune a Black Knight Butterfly Bush
Learn when and how to prune Black Knight Butterfly Bush for better blooms. Step-by-step spring pruning guide with timing and techniques.
Core guideBlack Knight Butterfly Bush Hardiness Zones: Where Will It Grow?
Black Knight Butterfly Bush thrives in USDA zones 5-9. Learn hardiness tips, winter survival, and how to grow this deep purple shrub in cold
Plant specificBlack Knight Butterfly Bush Bloom Time and Flower Color Explained
Black Knight Butterfly Bush blooms June-September with deep purple flowers and orange eyes. Learn bloom timing, color details, and how to ex
Core guideBlack Knight Butterfly Bush Buying Guide: What to Look For
Learn what to look for when buying Black Knight Butterfly Bush. Quality indicators, container sizes, pricing, and where to find the best pla
Core guideHow Much Sun Does a Black Knight Butterfly Bush Need?
Learn how much sun your Black Knight Butterfly Bush needs. Full sun requirements, zone-specific tips, and light assessment for vigorous bloo
Core guideWatering Black Knight Butterfly Bush: A Complete Guide
Learn when and how to water Black Knight Butterfly Bush. Master watering needs from establishment through drought tolerance—step-by-step gui
Core guideBest Soil for Black Knight Butterfly Bush: pH and Drainage Tips
Best soil for Black Knight Butterfly Bush requires pH 6.0-7.5 and excellent drainage. Step-by-step guide to amending soil and avoiding commo
Core guideHow Big Does a Black Knight Butterfly Bush Get?
Learn how big Black Knight Butterfly Bush grows: mature size, growth rate, pruning effects, and spacing requirements for gardens.
Core guide7 Common Black Knight Butterfly Bush Problems and How to Fix Them
Fix 7 common Black Knight Butterfly Bush problems: yellowing leaves, root rot, spider mites, aphids, leggy growth, winter dieback, and powde
Plant specificBlack Knight vs Dark Knight Butterfly Bush: What's the Difference?
Black Knight vs Dark Knight Butterfly Bush: Compare these cultivars, learn if they're different, and find out which suits your garden.
Black Knight Butterfly Bush questions
How big does Black Knight Butterfly Bush get?
It typically reaches 6-10 feet tall and 4-8 feet wide at maturity, though annual hard pruning can keep it smaller.
When should I prune it?
Prune hard in late winter or early spring, cutting back to about 12-18 inches (or to the ground where it dies back), since flowers form on new growth.
Is it deer resistant?
Yes, it is generally considered deer resistant, though no plant is completely deer-proof.
Will it attract butterflies?
Yes, the fragrant purple flower spikes are highly attractive to butterflies, bees, and hummingbirds.
Is Black Knight Butterfly Bush invasive?
Buddleja davidii, the species behind this cultivar, is considered invasive or restricted in parts of the Pacific Northwest and some other regions; check local regulations before planting.
Can I grow it in a container?
It can be grown in a large container for a season or two, but given its size it generally does best planted in the ground.