How to grow buddleia (butterfly bush)
Find out all you need to know about growing buddleja, in this detailed Grow Guide.
Buddleia is an easy and fast-growing shrub, that will suit any garden where there is sun and well-drained soil.
There are larger and smaller varieties, good for borders and pots. Commonly known as the butterfly bush, the flower heads are full of nectar and are a magnet for many insects.
Flowers come in a wide range of colours including purple, blue, pink and white and even yellow. Flowers appear continuously for around four to six weeks in late summer.
How to grow buddleia (butterfly bush)
Grow buddleia in moist but well-drained soil in full sun. Deadhead flowers to encourage more to form and cut back hard in late spring to prevent the shrub from becoming too big. This will also ensure flowering occurs slightly later in the season, meaning there is plenty of pollen and nectar available for butterflies in late summer.
Where to grow buddleia
Buddlejas will grow in almost any location – they're often seen growing out of brickwork and will happily colonise wasteland – in fact they're classed as invasive plants. However, to get the best out them as garden plants, choose a sunny spot, to encourage nectar-rich flowers and attract butterflies.
How to plant buddleia
If you have heavy clay soil, add a handful of grit to your planting hole for added drainage.
Watch Monty Don plant a buddleia in a border:
How to care for buddleia
If left to their own devices, buddleias can grow huge. They flower on new season’s growth, so give plants a hard prune in April or May, to cut out all the dead wood and maintain a good shape. This also encourages later flowering, which is good for butterflies such as the small tortoiseshell.
Watch Monty Don demonstrate how to prune a buddleia, in this Gardeners' World clip:
A high potash feed in spring will boost the flowering potential of your buddleia, but keep deadheading for a long-lasting flowering period. This will also prevent any unwanted spread of buddleia seedlings.
Watch Monty Don demonstrate how to deadhead buddleia in this clip from Gardeners' World:
How to propagate buddleia
Many varieties of buddleja will self-seed freely, but may not stay true to type. You can also propagate from semi-ripe buddleia cuttings in summer and hardwood cuttings in autumn.
Growing buddleias: problem solving
While relatively trouble-free, it's worth noting that buddleijas are on the invasive plants register and will readily escape onto train tracks, scrub land and into brickwork.
Buddleia varieties to try
- Buddleja davidii ‘Summer Beauty’ – a small variety, with deep pink flowers and narrow, green-grey leaves. It’s perfect for growing at the front of a border, or in containers.
- Buddleja davidii ‘Santana’ – with variegated leaves and wine-red flowers from July to September.
- Buddleja × weyriana 'Sungold' – unusual Buddleja with round clusters of golden yellow flowers with a strong fragrance.
- Buddleja davidii 'Ile de France' – deep purple flowers appear from July to September.
- Buddleja davidii ‘Buzz Sky Blue’ – compact and easy to grow with deep-blue flowers. Suitable for small gardens and containers.
- Buddleja alternifolia – different to the more familiar Buddleja davidii, the branches are slender and arching, bearing dense clusters of soft lilac-purple or pink fragrant flowers. The Royal Horticultural Society has given it the prestigious Award of Garden Merit (AGM).
Frequently Asked Questions
Where is the best place to plant a buddleia?
The sunniest spot in your garden is the best place to plant a buddleia. A sunny spot will result in the best flowers. You should also avoid windy spots, as strong summer gales could result in branches breaking off or the roots becoming exposed. When you purchase your buddleia, check its full-grown size and plant it with enough space to grow.
Is buddleia a tree or a bush?
Buddleia is not a tree, it is technically a shrub but is commonly known as the butterfly bush.
Are buddleia a problem?
Buddleia are on the invasive plants register, however if pruned and maintained in the garden they will not cause a problem. Buddleia can make a stunning addition to your garden, as well as producing flowers full of nectar for pollinating insects.