Extension Educator, Horticulture
Common names for plants tend to be fairly descriptive. We have Four O'clocks that bloom about 4:00 pm each day. Butterfly bush is well suited to its name since this plant is a butterfly magnet. Common names may be appropriate, but I'm still waiting for my money tree to live up to its name.
Butterfly bush, Buddleia davidii, attracts clouds of butterflies but is also just a great garden plant. They are known for their long arching spikes of summer blooming fragrant flowers in white, pink, lavender and purple. The leaf color is a nice gray green. Another species of butterfly bush, Buddleia x weyeriana, comes with yellow flowers. 'Sun Gold' is a common cultivar of the yellow form. The flowers are in bunches that look more like lantana. It may not be as winter hardy as Buddleia davidii.
Butterfly bushes are welcome additions to any garden, although they are not for small spaces. Depending on the cultivar, the plants grow from five to ten feet tall. They look nice mixed in a shrub border or flower garden. They do their best growth in moist soils in full sun. The first few years it is best to give them an extra drink of water during drought periods, but once established they are fairly drought tolerant.
Butterfly bushes tend to have long arching stems that remind me of gangly teenagers that haven't grown into their legs yet. I like to plant something in front like 'Autumn Joy' sedum, another butterfly magnet, just to hide the bush's bare knees.
In southern states butterfly bushes can become large shrubs. However here in Illinois depending winter severity the stems will die back to some degree. Some years the stems die all the way to the ground and the plants have to send up new shoots from the roots. No problem since they flower on current season's growth. Actually butterfly bushes look better if they are cut back to 10 to 12 inches in the spring no matter how much of the stem survives.
Some years I get reports of butterfly bushes dying over the winter. I believe they need a well drained spot so wet soils may kill them over the winter. Also some cultivars are just hardier than others; so don't give up if you have lost a few butterfly bushes over the winter.
There are many cultivars of butterfly bush. The Nanho series tends to be smaller and more compact. 'Nanho Blue' has pinkish blue flowers but still can reach five feet tall in one season. 'Black Knight' has dark purple flowers on 10-inch long panicles and tends to show good winter hardiness.
If you are a sucker for anything variegated, then 'Harlequin' butterfly bush is for you. The green and white leaves are attractive even when the plant is not flowering. It has purple flowers but doesn't grow as vigorously as many butterfly bushes.
One of my favorites is 'White Profusion'. It has a more shrub-like habit getting to 6 feet tall and about just as wide. The flower spikes are 6 to 8 inches long and cover the plant. 'White Bouquet' is similar but the flower spikes are fatter.
For continued bloom, the old flowers should be removed to encourage new growth and more flowers. Plus taking a moment to give your butterfly bush a good haircut gives you a chance to watch the butterflies