Buddleia: description, flowering time & winter hardiness


The butterfly bush scores with its splendid flowerheads and beguiling fragrance. Thanks to the long flowering period in summer, it offers insects plenty of nectar and pollen.

Butterfly bush
The butterfly bush impresses in a variety of colours [Photo: Dirk M. de Boer/ Shutterstock.com]

This shrub lives up to its name: numerous insects are attracted to the nectar of the delicate flowers. The flowers of the butterfly bush (Buddleja davidii) come in a variety of shades that will decorate any garden.

Buddleia: origin and properties

The butterfly bush has its origins in China and Tibet. Today, the genus is particularly widespread in tropical and subtropical areas of America, Africa and Asia. The butterfly bush belongs to the brownroot family (Scrophulariaceae) and offers insects the perfect place to collect nectar and pollen. The beautiful butterfly bush readily spreads and is therefore considered an invasive plant in many places. The deciduous, winter or evergreen semishrubs are highly fragrant because of the elongated and large flower panicles. Usually the flowerheads are so heavy that the branches overhang. The bark of the shrub is light brown and the leaves are opposite and lanceolate. Depending on the variety, a buddleia can reach a growth height of between 1.5 and 3 m.

Is there a difference between butterfly bush and buddleia? No, because when we speak of butterfly bush or buddleia, we always mean the same plant Buddleja davidii. They are simply names for the same thing. Despite the similarity, however, these are not related to the common lilac (Syringa vulgaris) – it belongs to the olive family (Oleaceae).

Butterfly bush flower
Despite the similarity, the common lilac is not related to the butterfly bush [Photo: Roca Mharas/ Shutterstock.com]

When does the butterfly bush flower?

Compared to the common lilac, the butterfly bush does not flower in spring, but in July. Numerous varieties with their splendid flowers delight the observer until well into autumn.

Is the butterfly bush insect-friendly?

The buddleia flowers offer many insects and especially butterflies an excellent source of nectar in midsummer and late summer – when many other plant species have already faded. The red admiral (Vanessa Atalanta), the comma (Polygonia c-album), the peacock butterfly (Aglais io) and the common brimstone (Gonepteryx rhamni) are often found on the butterfly bush. It is a real eye-catcher as a solitary planting, but also does well in a group planting with other beautiful, late summer flowers such as asters (Aster), orpine (Sedum telephium ˈAutumn joyˈ) or other perennials. We have summarised how to plant your butterfly bush in our special article.

Butterfly on Buddleia
The peacock butterfly is attracted to the fragrant flowers [Photo: Steidi/ Shutterstock.com]

How fast does the butterfly bush grow?

The Buddleja davidii is considered an invasive species with a strong tendency to spread. It can grow up to 2 m per year, depending on the variety. The strong-growing characteristic sometimes becomes a problem when spreading in an uncontrolled manner. Especially in dry locations, the plant can become very dominant. Therefore, the correct handling and care of the butterfly bush are extremely important. Pruning butterfly bush is an important measure here to prevent spread.

Is butterfly bush hardy?

Depending on the buddleia variety, the perennial is hardy down to -10 and -15 °C. It should be noted, however, that young plants are somewhat more sensitive and therefore require frost protection in the form of a thick layer of mulch. From the age of about 5 years, they defy cold temperatures without any problems. A butterfly bush cultivated in a tub should, however, be protected from frost as much as possible, even if the variety is winter-hardy. This is because, due to the smaller amount of substrate in the pot, the roots have no protection and can therefore freeze. The best place to overwinter potted plants is in a bright place with temperatures between 10 and 15 °C.

Is butterfly bush poisonous?

Buddleia is actually considered to be slightly poisonous, because it contains various toxins from the group of glycosides and saponins. The highest concentration is found in the leaves and seeds of the plant. If plant parts are swallowed, nausea, vomiting and abdominal cramps may occur as symptoms of poisoning.

Poisonous butterfly bush
The leaves and flowers of the butterfly bush in particular are poisonous [Photo: nadia_if/ Shutterstock.com].

Although the beautiful perennial spreads very well on its own, people often prefer to propagate the plant specifically. We explain how to go about propagating butterfly bush.

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