Why Is My Butterfly Bush So Thin?

Butterfly bushes produce large panicles of flowers that attract butterflies.

Butterfly bushes are popular shrubs since they are easy to grow and produce large, cone-shaped clusters, or pannicles, of flowers that attract butterflies. The plants have invasive potential in some areas due to lack of competition by native plants. Because butterfly bushes become established so easily, the plants are not prone to weak growth. Thin, weak or spindly branches are a sign of distress in the butterfly bush.

Becoming Overgrown

In northern climates, butterfly bushes will die back to the ground, but in southern climates the plants they remain evergreen. Evergreen butterfly bushes have a tendency to become leggy if they are not pruned on a regular basis. The plants are aggressive growers and will spring back from severe pruning by the beginning of the next growing season. Pruning butterfly bushes keeps them shrub-like in stature. The plants may be completely cut back in the fall of each season and will reemerge from the roots of the plants in spring.

Lack of Sunlight

Butterfly bushes may be grown in full sun or partial shade. Plants that are grown in full shade may become leggy due to lack of light reaching the plant. This can happen over time as surrounding trees and shrubs grow in size. Gardeners faced with this issue can cut back butterfly bushes and move the root ball of the plant or trim back surrounding foliage to allow more light to reach the plant.

Tools

Useful cutting tools include hand saws, branch loppers and hand shears such as scissors-type shears and anvil-type shears. Hand shears may be used to cut shrubs that are up to 3/4 inch in diameter. Branch loppers may be used to cut branches up to 1 1/2 inch in diameter. Pruning saws should be used on branches larger than 1 1/2 inch in diameter.

Suckers

Butterfly bushes also produce tiny offshoot plants, which are known as suckers. Suckers can pull energy from a mother plant and cause the branches of the plant to look thin, spindly or weak. Sucker plants may be cut down using branch loppers or mowed over using a lawn mower.

References

• Maryland Cooperative Extension; Butterfly Bush Production and Consumer Care; Dr. Yin-Tung Wang et. al
• University of Missouri Extension; Pruning Ornamental Shrubs; Christopher J. Starbuck; August 2007
• The Sun Sentinel; Prune Leggy Blue Butterfly Bush in June; Robert Haehle; February 03, 2010

Resources

• NC State University Extension; Pruning Shrubs; Erv Evans; 2003
• Mountain Valley Growers; Butterfly Bushes
• University of Florida IFAS Extension; Butterfly Bush