Butterfly Bush Plant Profile

Butterfly bush (image) is pretty, a butterfly magnet - and invasive in many areas. It's perennial.
David Beaulieu

Butterfly bush (Buddleia davidii) is a deciduous shrub with an arching habit and impressive flowers, but it has a mixed reputation. It's easy to grow and produces striking flower spikes. Thanks to the magic of cultivar developers, the flowers now come in a number of colors, including pink, yellow blue, and multicolors. And as the name suggests, these shrubs are known as magnets for butterflies, which are the closest thing to real fairies that our gardens will ever enjoy. Red-flowering butterfly bushes will even attract hummingbirds. 

Butterfly bushes are cultivated to suit many different gardening preferences. Some can grow up to 12 feet tall, while others are relatively small. Some varieties produce large clusters of flowers while others produce flowering spikes. Butterfly bushes were first brought to England from Asia in 1774 by the botanist Adam Buddle (for whom the plant was named). New varieties are still being discovered in remote areas of China and the Himalayas.

But while the plant is enjoyed by many, butterfly bush does have an equal nuber of detractors. In many areas of the United States, it's actually considered an invasive plant—one that does not naturally grow in a particular region but which is pervasive enough to push out native plants. Thus, many plant experts caution against planting butterfly bush under any circumstance.

Invasive plants are problematic because they can alter ecosystems and damage existing flora and fauna. Although not invasive everywhere, butterfly bush is meddlesome enough to have given the plant a bad name. Several states now classify it as a noxious weed. There are good reasons not to plant the butterfly bush, especially in regions where it is an identified problem.

Botanical Name Buddleja davidii 
Common Names Butterfly bush
Plant Type Deciduous shrub
Mature Size 4 to 12 feet tall; 3- to 8-foot spread (depends on variety)
Sun Exposure Full sun
Soil Type Medium moisture, well-drained soil
Soil pH 6.0 to 7.0; slightly acidic to neutral
Bloom Time June to September
Flower Color Shades of purple; also pink, blue, white, yellow
Hardiness Zones 5 to 9 (USDA)
Native Area Rocky slopes in China

How to Grow Butterfly Bush

The popularity of butterfly bushes is no surprise as they're beautiful, easy to grow, and require minimal day-to-day care. Even major storms have little effect on these hardy shrubs. They thrive in harsh environments, such as polluted urban settings. They're also resistant to insects, drought, and stress. The bushes require little attention, so even weekend gardeners can enjoy their lovely blooms and resident butterflies.

Butterfly bush is very easy to grow in average, medium moisture, well-drained soil in a full sun location. If planting more then one, space them well apart—five to six feet. Blend in peat moss before planting if the soil is dense and poorly draining.

In colder climates, butterfly bush often dies back to the ground in winter and is treated like a herbaceous perennial. And in warm climates, they can be pruned back in the same way to keep them under control and stimulate better blooming. Be wary of this plant's tendency to aggressively spread through self-seeding. Removing the spent flower clusters before they can scatter seeds will help control the plant.

There are no serious pest or disease problems with butterfly bush, although spider mites can be an issue, and nematodes can be a problem in the South.

Light

Butterfly bush needs full sun and will become weedy and sparse if grown in shady conditions.

Soil

This plant will thrive in any average, well-drained soil that gets an average amount of moisture.

Water

This plant likes a medium-moisture environment and will do poorly in boggy locations that don't drain well. They will thrive on 1/2 inch of water by rain or irrigation each week.

Temperature and Humidity

Butterfly bush thrives throughout its hardiness zone range, but expect it to die back to ground level in winter in zones 5 and 6.

Fertilizer

This plant needs no fertilizer, other than a thin layer of compost spread over the root zone each spring.

Propagating Butterfly Bush

It's rare that you would seek to propagate this bush, since it spreads so readily, but if you do, collecting the seeds heads will give you plenty of seeds to replant wherever you wish.

Propagation by seed is not possible if you have wisely chosen a sterile, seedless variety of butterfly bush. With these, propagating by spring branch cuttings is the best approach.

Varieties of Butterfly Bush

Butterfly bush should be planted with caution, and only if you are willing to remove spent flower heads to avoid spreading the seeds. While there are many popular varieties, including Buddleia x weyeriana 'Bicolor', and Buddleja davidii 'Black Night', better choices are offered by newer non-seeding varieties:

  • Buddleja x 'Blue Chip' is a smaller, 3- to 6-foot variety that is sterile and produces no seeds. Its flowers are purple.
  • Buddleja 'Miss Ruby' is another sterile variety, growing 4 to 5 feet tall and wide, with pinkish-purple flowers.

Other cultivars that are bred to be seedless include 'Asian Moon', 'Ice Chip', 'Inspired Pink', 'Purple Haze', and the various Flutterby Grande cultivars.

Pruning

The spent flower spikes of butterfly bush should be removed promptly after flowering to stimulate continued blooming right up to frost. This plant grows very fast, and pruning it down all the way to ground level each spring stimulates vigorous growth and profuse flowering.