How to Care for Butterfly Bushes
By midsummer, butterfly bushes, Buddleia davidii, are in full bloom, producing long, graceful wands of flowers that swallowtails, monarchs and many other butterflies — as well as hummingbirds — can’t resist.
These fast-growing deciduous shrubs are suitable for planting in perennial borders, cottage gardens, island beds or wherever their loose, somewhat messy growth habit won’t detract from a particular garden design you’re trying to achieve. The plants tend to sprawl as they grow up to 12 feet tall, although you can opt for dwarf types with a neater, more compact growth habit if you’re going for a groomed look.
The flowers, which start opening in summer and continue into fall, come in red, pink, violet, yellow, purple, white and lavender and are held in dense panicles that often have a fruity or honeyed scent. Look closely and you’ll find that many of the flowers also have pretty orange “throats.”
Butterfly bushes, sometimes called summer lilacs, are recommended for USDA hardiness zones 5 to 10 and need full sun and fertile, well-drained soil. Dig a hole about twice the diameter of the root ball, and set your plant in the garden no deeper than it was growing in its nursery pot.
For maximum impact, plant butterfly bushes in masses. Space them 5 to 10 feet apart, or as directed for the variety you’re using. Give them about an inch of water a week while they’re actively growing, if rain isn’t sufficient, but don’t worry if you occasionally forget to irrigate. In the first year after planting, butterfly bushes need regular water to develop strong roots. After they’re established these plants are relatively drought-tolerant. Fertilizing isn’t usually necessary, as it encourages foliage at the expense of flowers.
You can prune butterfly bushes anytime, and you will probably need to prune a few times each summer to keep them under control. Keep faded flowers deadheaded to encourage more blooms.
Buddleia are seldom bothered by pests or disease, although mullein moths, caterpillars and spider mites can attack them, and the plants are occasionally plagued by fungal infections. If you see insects, try knocking them off with a strong blast of water from the hose, or spray the bushes with insecticidal soap. But try to avoid using pesticides, as they also kill visiting butterflies, bees and other beneficial garden creatures.
To control fungus problems, which can flourish on wet leaves, water bushes early in the day, and use a soaker hose or drip irrigation when possible. Remove diseased plant parts and discard them — but not in your compost pile, where diseases can spread.
Mulch the plants generously to protect them during the winter. Many gardeners prune their butterfly bushes all the way to the ground as winter approaches. When the bushes break dormancy the following spring, give them some compost and fresh mulch. If you didn’t prune during the winter, it’s okay to prune just before a flush of new growth appears.
Popular butterfly bush varieties:
‘White Profusion’ –These tall plants produce large spikes of snowy-white flowers.
‘Black Knight’ – Grows to 6 feet with a 4- to 6-foot spread. The flowers are dark purple.
‘Pink Delight’ – Pink flowers stand out against this plant’s silvery-green foliage. It matures at 4 to 6 feet in both height and width.
‘Lilac Chip’ – A dwarf with fragrant lavender-pink flowers. This variety is seedless, so the plant doesn’t need deadheading.
‘Peacock’ – A compact-sized plant that bears medium-sized pink flowers. Grows only about one-third the size of other varieties.
Note: Buddleia, an Asian native, can crowd out native species in North America. Some states now ban butterfly bushes on public grounds or prohibit commercial cultivation and sales of the plants. If you’re in doubt about growing butterfly bushes in your area, check with your county extension service office or see the USDA list of invasive weeds.