Butterfly Bush ~ Buddleja davidii Plant Care Guide ~ Summer Lilac
Botanical name: Buddleia davidii
Plant type: Shrub
Sun exposure: Full Sun
Soil type: Any
Soil pH: Varies
Want a guaranteed butterfly and hummingbird magnet? Or, one of the most fragrant of shrubs? Plant a buddleia (butterfly bush).
This fast-growing, deciduous shrub with long, arching shoots will reach heights of 6 to 8 feet. Although the green leaves add a welcome bit of color to any landscape, it is the masses of blossoms—long, seductively spiked trusses—that are special. From summer to autumn, the butterfly bush bears dense panicles, 12 inches or more long, that fill the air with a fruity scent.
At its northern limits, the shrubs can die back, sometimes all the way to the ground. No matter. Butterfly bush is vigorous and undemanding and will send up new shoots, given a sunny location and average garden soil.
Note: Butterfly bush can be an invasive species in some areas; check with your local cooperative extension before planting.
- Buddleias need full sun and fertile, well-drained soil.
- Plant in spring or fall.
- Loosen the soil, mix in compost, and dig a hole twice the diameter of the plant container.
- When placing the plant in the hole, the top of the rootball should be level with the soil surface
- Space plants 5 to 10 feet apart, depending on the variety.
- Water thoroughly.
- Water freely when in growth and sparingly otherwise. In the summer, water if rainfall is less than 1 inch per week.
- Avoid fertilizing butterfly bush; too much fertility supports leaf growth over flower production.
- Remove spent flower spikes to encourage new shoots and flower buds.
- Each spring, apply a thin layer of compost and mulch to retain moisture and control weeds.
- In cold Northern climates, spread mulch up to 6 inches deep around the trunk to nurture it through the winter.
- Buddleias are very late to break dormancy, so don’t be in a hurry to assess winter damage.
- The bush should bloom abundantly even in its first year. In warmer climates, the bushes will grow into trees and develop rugged trunks that peel; peeling is normal.
- In the northern limit of their range, they behave as herbaceous perennials, dying back to the root in cold winters.
- Since they bloom on new wood, even if there is no die-back, cut them back to the ground every spring. Even where winters are mild enough for the stems to survive, prune severely to stimulate abundant growth on which flowers are borne.
- Susceptible to capsid bug, caterpillars, weevils, mullein moth, and spider mites.
- Fungal leaf spots and die-backs can occur.
- ‘Lockinch‘ is a spreading, vigorous, deciduous shrub with long, arching shoots. mid-green leaves, and fragrant violet-blue flowers. Grows 8 feet tall and 10 feet wide.
- ‘Petite Indigo‘ (syn. ‘Nanho Blue‘) has slender leaves and narrow panicles of pale lilac-blue flowers. Grows 4 to 5 feet tall and wide.
- ‘White Profusion‘ has large, very white flower spikes and grows 10 feet high and 15 feet wide.
- Attracts Butterflies
- Attracts Birds
In his 1979 revision of the taxonomy of the African and Asiatic species of Buddleja, the Dutch botanist Anthonius Leeuwenberg sank the six varieties of the species as synonyms of the type, considering them to be within the natural variation of a species, and unworthy of varietal recognition.  It was Leeuwenberg’s taxonomy which was adopted in the Flora of China published in 1996. However, as the distinctions of the former varieties are still widely recognized in horticulture, they are treated separately here:
Buddleja davidii cultivars are much appreciated worldwide as ornamentals, but perhaps more so for the value of their flowers as a nectar source for many species of butterfly. However, this species is not able to survive the harsh winters of northern or montane climates, being killed by temperatures below about -15 to -20 °C (5 to -4 °F). Even if not killed to the ground, the shrub is usually hard-pruned to just above the lowest pair of leaf buds, i.e. to within 15 – 25 cm of the ground, in spring once frosts have finished, as the younger wood is more floriferous. Deadheading is also of great value, in extending a flowering season otherwise limited to about 6 weeks, although the flowers of the second and third flushes are invariably smaller; the practice also reduces the nuisance of self-seeding. USDA zones 5 – 9. 
There are approximately 180 davidii cultivars as well as numerous hybrids with B. globosa and B. fallowiana grown in gardens. Many of these cultivars are of a dwarf habit growing to no more than 1.5 metres (4.9 ft). The following davidii cultivars held the RHS Award of Garden Merit in 2012:-
See Also ….