Light Needs
Mature Height
Mature Spread
Growing Zones
Loaded with large summer flowers, Black Knight Butterfly Bush (Buddleja davidii) should hold a special spot in your landscape. The shrub grows to a height of nearly 8 feet and almost 6 feet around. It's an easy-care addition to low-water, Mediterranean, cottage or natural garden styles. Each spring, rains bring rapid growth to butterfly bushes. Black Knight's long arching stems cascade downward, and the tips are filled with the large, cone-shaped flowers that average 4 to 10 inches long.
The large purple flowers of Black Knight Butterfly Bush actually are made up of many tiny deep purple blooms, each perfect for hummingbirds and butterflies gathering sweet nectar. The flowers are fragrant for humans to enjoy, too. Black Knight continues blooming throughout summer and into early fall. Deer and rabbits leave butterfly bushes alone. The drought-tolerant shrub comes back year after year in zones 5 through 9.
Black Knight Butterfly Bush Care
Black Knight Butterfly Bush is an easy shrub to grow, so it's a winner in most landscapes. Choose a sunny spot and soil that drains well; the shrub performs best with a little afternoon shade in hotter regions of zones 8 and 9. Be sure to plant your butterfly bush so the crown is just above the soil level once you water at the base. Cut the butterfly bush stems down to a few feet above the ground each spring when new growth appears at the bottom of the plant. There is no need to deadhead this beauty, but you can cut the flowers for arrangements.
Black Knight Butterfly Bush Spacing
Plant a colorful cascading border with several Black Knight Butterfly Bush for a butterfly gathering place in your landscape. Space the shrubs 5 to 6 feet apart from center to center to give them room to grow to full size.
Black Knight Butterfly Bush Plant Facts
Growing Conditions
- Hardiness ZonesGrowing Zones
- USDA Zones 5 to 9 (perennial); grown as an annual elsewhere (outdoors year-round); grown indoors elsewhere (outdoors year-round); grown in containers elsewhere (grown as a seasonal crop)
- Sun Exposure
- Full Sun (6+ Hours Direct Sun)
- Mature Height
- 8-10 Feet
- Mature Spread
- 4-6 Feet
- Growth Rate
- Fast
- Growth Habit
- , Trailing
- Water Needs
- Average
Flowers & Foliage
- Flower Colors
- , Purple
- Flower Description
- Dark purple
- Bloom Time
- Summer to Fall
- Blooms On
-
New Wood
?
"Blooms on" tells you which stems produce flowers, which decides when it's safe to prune.
- New Wood: Flowers form on stems that grow this season. Prune in late winter or early spring without losing blooms.
- Old Wood: Flower buds form on last year's stems. Prune right after flowering. Pruning in fall or early spring removes next year's blooms.
- Both New and Old Wood: Blooms on last year's stems and again on new growth, so it flowers even after a hard winter or a mistimed pruning. Prune lightly after the first flush of blooms.
- When to Prune
- Late winter to early spring, before new growth starts
- Foliage Color
- , Green
- Foliage Description
- Gray-green
- Foliage Type
- , Deciduous
- Seasonal Interest
- , Summer Flowering, Fall Flowering, 3 Season Interest
Garden Benefits
Plant Overview
- Common Name
- Black Knight Butterfly Bush
- Botanical Name
- Buddleja davidii 'Black Knight'
Simple Plant Spacing Calculator
Please Note: The pictures below are to give a general representation of the different container sizes. The actual size/ages of plants are estimates and will vary based on type of plant, time of year, last pruning & many other factors.
Also Known As:
Quart
Plant Age:
~ 6 months - 1 year
Plant Size:
~ 4"-8"
Pot Size:
~ 4.75"H x 4.5"W
Volume:
1.50 quarts
Also Known As:
2.5 Quart Pot
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 8"-12"
Pot Size:
~ 6.5"H x 6.5"W
Volume:
2.20-2.30 quarts
Also Known As:
#1 Container
1 Gallon
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 10"-14"
Pot Size:
~ 7"H x 7.75"W
Volume:
2.26-3.73 quarts
Also Known As:
#2 Container
2 Gallon
Plant Age:
~ 1.5 - 3 years old
Plant Size:
~ 12"-18"
Pot Size:
~ 9.5"H x 9.5"W
Volume:
1.19-1.76 gallons
Also Known As:
#3 Container
3 Gallon
Plant Age:
~ 2 - 4 years old
Plant Size:
~ 12"-30"
Pot Size:
~9.5"H x 11"W
Volume:
2.32-2.76 gallons
Also Known As:
#5 Container
5 Gallon
Plant Age:
~3-4 years old
Plant Size:
~ 20" - 60"
Pot Size:
~11" H x 10 1/2” W
Volume:
3.5 - 4 gallons
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Starting January 1, 2026 all bushes, perennials & trees purchased come with an extended 1-year warranty for added confidence. If your plant dies due to a health issue within a year, we’ll make it right.
Plants that are currently in stock typically ship within 2-7 business days after your order is placed.
Plant Addicts ships to the lower 48 states within the U.S. Unfortunately, we do not currently ship to Alaska, Hawaii, or internationally.
This plant cannot be shipped to the following states: ID, OR, WA, AK, HI. These restrictions apply only to this specific plant due to agricultural regulations or other limitations. Other plants may still be available for shipping to these states.
If you have any questions about shipping restrictions, feel free to reach out to our team!