Care Instructions for a Black Knight Butterfly Bush


For an easy-maintenance, drought-resistant shrub with dramatic appeal, try the "Black Knight" butterfly bush, sometimes known as summer lilac. Black Knight (Buddleia davidii) produces prolific dark purple spikes of flowers that attract butterflies all summer long. The blooms form on willowy branches that can reach lengths of 10 feet if not pruned back. This lovely shrub grows best in naturalized settings and can be invasive in very moist, warm soil.

Step 1

Fertilize the Black Knight butterfly bush in early spring by applying a 10-10-10 granular fertilizer to the soil underneath it, according to package directions. Don't fertilize in moist climates where the butterfly bush grows aggressively.

Step 2

Water the shrub weekly to keep the soil evenly moist until it is well established. Thereafter, water as needed when the soil is dry. Butterfly bushes grow in very dry climates and are somewhat drought tolerant. However, they grow more quickly with occasional watering.

Step 3

Prune back the "Black Knight" butterfly bush in early spring to 24 inches high. If the plant is invasive, cut it back to the ground to slow its growth.

Step 4

Spray off spider mites with a hose. Don't use insecticides on butterfly bushes because you'll kill the butterflies and bees that visit this shrub.

Things You'll Need

  • 10-10-10 fertilizer
  • Pruning shears


  • Fine Gardening: Buddleia davidii 'Black Knight'
  • Floridata: Buddleja davidii

Who Can Help

  • This Old House: 15 Foolproof Shrubs
Keywords: black knight bush, growing butterfly bush, butterfly bush care

About this Author

Julie Christensen has been writing for five years. Her work has appeared in "The Friend" and "Western New York Parent" magazines. Her guide for teachers, "Helping Young Children Cope with Grief" will be published this spring. Christensen studied early childhood education at Ricks College and recently returned to school to complete a degree in communications/English.