Flowering time (month)
Ornamental or utility value
nectar or pollen plant
alkaline to slightly acidic
The butterfly bush (Buddleja davidii) originates from China and gives its name to the family of summer lilac plants. The widespread German name Sommerflieder, however, is somewhat misleading: although its upright flower panicles are reminiscent of the inflorescences of the flied, the two woody plants are not more closely related.
The botanical genus name Buddleja was already established by Carl von Linné in the middle of the 18th century in honour of the British botanist Adam Buddle. The butterfly bush has been a common garden plant in Europe for several centuries and has adapted so well to the local conditions that in many places it also occurs in the wild as a so-called neophyte. It mainly populates dry, sandy and gravelly soils, such as abandoned railway lines and industrial wastelands. Here, the butterfly bush is more competitive than most native shrubs with its resistance to drought and rapid growth. In Switzerland, the garden forms of the butterfly bush may no longer be sold in many places due to the neophyte problem. Despite its ecological concerns, the butterfly bush is also an important food plant for various butterfly species in Switzerland. Especially the peacock butterfly is magically attracted by the nectar-rich flowers in late summer. But also hoverflies, bumble bees and bees are frequently to be found on the flower candles.
The butterfly bush grows upright and forms a funnel-shaped crown of several basic branches with slightly overhanging side shoots. The height of growth varies depending on the variety: dwarf forms are only around 120 centimeters high, larger varieties up to three metres and almost as wide. The butterfly bushes grow very quickly, especially on nutrient-rich, fresh soils. The bark of the branches is light brown to grey and peels off with age in felty stripes.
The foliage of the butterfly bush is opposite. The leaves are eilanzettlich formed, 10 to 20 centimeters long, dark green and gray-felt on the underside. In mild winters they stick to the branches until spring.
The terminal flower panicles of the butterfly bush form during the summer at the tips of the new main shoots and at the ends of the upper side shoots. The flower panicle of the main shoot can be up to 40 centimeters long in the fast-growing varieties. The butterfly bush usually opens its first flowers in July and flowers through to frost. Depending on the variety, the flower colours vary between white, light purple, purple red and dark purple. Many varieties of the butterfly bush have an intense fragrance.
The fruits are so-called capsule fruits. The seeds contained in older varieties often sow themselves. Due to the neophyte problem, however, there are now also dwarf forms with sterile flowers.
The butterfly bush needs a sunny, warm place in the garden. Protection from cold easterly winds is advantageous. The bushes are otherwise extremely drought-resistant, heat-resistant and also cope well in the city climate.
A moderately dry, slightly sandy or gravelly soil with a moderate nutrient content is ideal for the butterfly bush. Here the wood matures well until winter and is also more resistant to breakage than on moist, nutrient-rich garden soils.
Butterfly bushes are offered in pots from spring to autumn and can basically be planted all year round. However, the spring and early summer months should be preferred, as late planting can cause failures in very cold winters. If the soil is well permeable and not too damp, it is not necessary to prepare the soil. On very damp soil, you should work building sand into the soil around the root ball.
You can do without special care measures for summer lilac. It needs neither fertilizer nor regular watering to bloom abundantly every year.
To ensure that the summer lilac blooms abundantly every year, it should be pruned vigorously with garden shears in late winter. Simply cut back all the main branches to a few pairs of eyes and remove the thinner side shoots completely. This results in a strong new shoot with particularly large flower panicles. However, do not wait too long with the cutting measure in spring – the later you cut, the later the flowering starts in summer.
The butterfly bush is an enrichment for every flower garden. It attracts numerous insects with its flowers, is extremely frugal, robust and blooms continuously throughout the summer. It can be placed very well in the rock garden and – preferably as a group – integrated into summer herbaceous and woody borders. It harmonises well with ornamental grasses, fat hens, purple sun hats and other summer bloomers. Dwarf varieties are also excellent winter-hardy tub plants, which even forgive forgetting to water for a few days.
The wild species of the butterfly song is of little importance in garden culture. In the garden specialized trade exclusively breeding forms, the so-called Buddleja Davidii hybrids, are offered. Here is a small selection of recommended varieties: ‘Blue Horizon’: a good 3 metres high; blue-violet flower panicles; very rich-flowering ‘Border Beauty’: about 2 to 2.5 metres high; loosely upright growing; up to 45 centimeters long slender carmine pink flower panicles ‘Dart’s Ornamental White’: around 2.5 metres high; panicles up to 40 centimeters long with white flowers ‘Foxtail’: around 2.70 metres high; light purple flowers in panicles up to 40 centimeters long, rich and good post-flowering ‘Pink Delight’: old variety, around 2.5 metres high; panicles up to 40 centimeters long, dense with individual purple pink flowers
Purple Emperor’: medium-strong growing, almost 2 metre high variety; violet, around 30 centimeter long flower panicles; early flowering with a strikingly strong scent; good postflowering
Chip’ hybrids: small, around 120 centimeter high varieties with sweeping crowns and sterile flowers in blue violet, purple, purple or white. The varieties are named after the flower colour, for example ‘White Chip’ or ‘Blue Chip’.
Butterfly bushes can easily be propagated by cuttings. For this purpose, in June, partial cuttings are cut from the side shoots and rooted in growing boxes covered with foil or plastic hoods with sowing soil. An increase as Steckholz in the autumn or late winter is also possible.
Diseases and pests
As a rule, the butterfly bush is hardly affected by diseases and pests. In rare cases, damage to the leaves caused by caterpillars or by the weevil can occur. Spider mite infestation also occurs. During prolonged warm and humid weather the downy mildew sometimes spreads on the plants.
Whether fruit, vegetable and ornamental plants in the garden or indoor plants in the house: spider mites can infest and damage many different plants. Here René Wadas, a herbalist, will tell you his tips on how you can effectively fight the arachnids.Credits: Production: Folkert Siemens; Camera: Fabian Primsch; Editing: Dennis Fuhro, Photos: Flora Press/FLPA, GWI
Summer Lieder in the our store Shop
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.