Maintenance Landscaping Design

Buddleja black knight is an ornamental plant that is known for its black leaves and flowers. This plant is native to China and Japan and was introduced to North America in the early 1900s. The black knight buddleja is a deciduous shrub that can grow up to 10 feet tall and wide. This plant prefers full sun to partial shade and well-drained soil. The flowers of this plant are black, purple, or blue and bloom in the summer.

Popular name

• Black Knight Butterfly Bush
  
• Burgundy Butterfly Bush
  
• Dark Knight Butterfly Bush
  
• Midnight Butterfly Bush
  
• Purple Knight Butterfly Bush

Good to Know

• Buddleja black knight is a shrub that can grow up to 4 feet tall.
  
• It has dark green leaves that are up to 6 inches long.
  
• The plant produces clusters of black flowers that are up to 2 inches long.
  
• Buddleja black knight blooms from June to September.
  
• The flowers are pollinated by bees and other insects.
  
• The plant is native to China and Japan.
  
• It was introduced to North America in the early 1900s.
  
• Buddleja black knight is considered an invasive species in some parts of the United States.
  
• It can be controlled by regularly cutting back the plant.
  
• Buddleja black knight can be poisonous to humans and animals if ingested.

Related plant:
Buddleja Davidii Nanho Blue

Planting Process

1. For buddleja black knight, first step is to purchase a young plant from a nursery or online retailer.
   
2. Choose a planting location that receives full sun and has well-drained soil.
   
3. Dig a hole that is twice the width and depth of the plant’s root ball.
   
4. Place the plant in the hole and backfill with soil.
   
5. Water the plant deeply immediately after planting.
   
6. Apply a layer of mulch around the base of the plant.
   
7. Buddleja black knight generally does not require much fertilizer, but you can feed it once a year with a slow-release fertilizer.
   
8. Prune the plant annually in late winter or early spring to encourage new growth.
   
9. Avoid over-watering, which can lead to root rot.
   
10. Watch for pests and diseases, such as aphids and powdery mildew, and treat as needed.

Related plant:
Buddleja Royal Red

The Soil

About soil condition, black knight buddleja prefers well-drained soil that is rich in organic matter. The plant is quite tolerant of different soil types, but it will not perform well in waterlogged or extremely dry conditions. For best results, apply a layer of compost or organic matter to the planting area before adding the black knight buddleja.

About light

Similar to other Buddleja, the Black Knight requires full sun to partial shade in order to thrive. It grows best in well-drained soil, but is tolerant of a wide range of soil types. This shrub is moderately drought tolerant once established.

Good Temperature

The temperature condition that is best for Buddleja Black Knight is warm weather. This plant does not like cold weather and will not do well in it. The plant needs to be in an environment that is around 70 degrees Fahrenheit or above to thrive. If the temperature outside is too cold, the plant will not be able to grow properly.

Humidity Aspect

Ideal humidity condition for this plant is around 50%. If the humidity gets too high or too low, the plant will suffer. Too much humidity will cause the leaves to droop and the plant to become floppy. Too little humidity will cause the leaves to turn brown and fall off.

The Fertilizer

For the fertilizer, usually the plant doesn't need much. A light dressing of an all-purpose fertilizer in the spring is all that is necessary. As for the root, it is best to keep it moist but not wet and to fertilize regularly.

Plant Pruning

Pruning your Buddleja Black Knight is an important part of keeping your plant healthy and looking its best. Pruning helps to encourage new growth and can also help to control the size and shape of your plant. When pruning, be sure to remove any dead or damaged branches and stems. You can prune your Buddleja Black Knight in late winter or early spring.

About Propagating

Propagation is typically by stem cuttings taken in spring or summer. Remove a length of stem with some leaves attached and pot up in moistened, well-drained propagating mix. Place in a propagator or warm, bright spot out of direct sunlight to keep the compost moist and encourage rooting. Once rooted, pot on and grow on in moist, well-drained soil in sun or semi-shade.

Plant Growth

Usually, the plant growth rate is about 1-2 feet per year, but can be as much as 3-4 feet in rich soils with good drainage and regular watering. They are fast-growing, heat and drought tolerant, and relatively low-maintenance once established.

Basic Problems

Common problems for this kind of plant are that the leaves may turn yellow and the plant may not flower. The reason for these problems is usually due to too much water or fertilizer. If you think your plant has these problems, you should check the soil to see if it is too wet or too dry. You may also need to adjust the amount of fertilizer you are using.

List to Know

• Remember to water your buddleja black knight regularly, as it will not tolerate drought conditions.
  
• Fertilize your plant every few weeks during the growing season to ensure healthy growth.
  
• Prune back any dead or damaged growth as needed to tidy up the plant and encourage new growth.
  
• This plant does best in full sun to partial shade, so make sure to provide it with plenty of bright light.
  
• While buddleja black knight is not susceptible to many pests or diseases, be on the lookout for aphids and scale insects which can occasionally infest the plant.
  
• If you live in an area with cold winters, it is best to plant your buddleja black knight in a pot that can be brought indoors to overwinter.
  
• In the spring, you can start your buddleja black knight from seed or purchase young plants from a nursery.
  

Substitution

• Buddleja madagascariensis
  
• Buddleja macrostachya
  
• Buddleja marrubiifolia
  
• Buddleja maximowiczii
  
• Buddleja media
  
• Buddleja melindae
  
• Buddleja meridionalis
  
• Buddleja micrantha
  
• Buddleja microphylla
  
• Buddleja microstachya

Source:
JC Raulston Arboretum - Photographs of Buddleja davidii 'Black Knight'
Buddleia alternifolia | Landscape Plants | Oregon State University
Managing Pests in Gardens: Trees and Shrubs: Buddleia—UC IPM - ucanr.edu