How to grow buddleia (butterfly bush)
All you need to know about growing buddleia, in this detailed Grow Guide.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
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| Plant | yes | yes | yes | yes | yes | |||||||
| Flowers | yes | yes | yes | |||||||||
| Prune | yes | yes | yes |
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Plant Size: Height: 200 Spread: 150 |
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 of the buddleia plant 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, and appear continuously for around four to six weeks in late summer. BuddleIa will grow in almost any location – it's often seen growing out of brickwork and will happily colonise wasteland. It's classed as an invasive plant in the UK, but isn't currently on the Schedule 9 list of invasive non-native plant species. It offers plentiful nectar for pollinating insects and provides a food source for some species of insect larvae, though it can shade out other larval food plants.
Where to grow buddleia
The sunniest spot in your garden is the best place to plant a buddleia for nectar-rich flowers and to attract butterflies. 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.
When to plant buddleia
Ideally, plant buddleia in late spring once the soil has warmed. Hardy species can be planted at any time of year, provided the ground isn't waterlogged or frozen, but summer planting requires lots of watering, whereas planting in spring enables plants to get established before drier, hotter weather arrives.
How to plant buddleia
Plant buddleia in any free-draining soil in sheltered sunny spot. 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
Water plants for the first year or two in dry periods, until they’re well established and add a 5cm layer of organic mulch, such as garden compost, annually to retain moisture in the soil. Buddleia in fertile soil don’t require feeding, but in poor soil, a high-potash feed in spring will boost the flowering potential of your plant. Buddleia in containers need to be fed annually with slow-release fertiliser or liquid feed through the growing season.
Hardy buddleias planted in the ground don’t need any special care over winter. Plants in pots may suffer when the weather is freezing, so wrap containers in fleece or move them to a frost-free area. More tender buddleias like Buddleja officinalis need protection over winter.
The spread of buddleia can be controlled by deadheading plants before seeds develop, but if you don’t want to spend time deadheading, you might choose not to plant buddleia in your garden and instead opt for other species for pollinating insects. Watch Monty Don demonstrate how to deadhead buddleia in this clip from BBC Gardeners' World:
How to prune 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. Most buddleias don’t require pruning in autumn, but can be cut back lightly if necessary and dead flowerheads should be removed.
Watch Monty Don demonstrate how to prune a buddleia, in this BBC Gardeners' World clip:
How to propagate buddleia
Many varieties of buddleIa 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.
Pests and diseases
Buddleias are generally free from pests and diseases. However, recent reports of aphid damage are currently being investigated by RHS scientists. Possible symptoms include curled leaves, pale or yellow patches and aphids on the underside of leaves. If you think your buddleia has aphids, you can submit your findings to the RHS study.
Buddleia varieties to try
Buddleja davidii 'Nanho Blue' – a small variety, with lilac-blue flowers and narrow, green-grey leaves. It’s perfect for growing at the front of a border, or in containers. Height x Spread: 1.5m x 1.5m
Buddleja davidii ‘Santana’ – with variegated leaves and wine-red flowers from July to September. H x S: 4m x 4m
Buddleja × weyriana 'Sungold' – unusual Buddleja with round clusters of golden yellow flowers with a strong fragrance. H x S: 4m x 3m
Buddleja davidii 'Ile de France' – deep purple flowers appear from July to September. H x S: 3.5m x 3.5m
Buddleja davidii ‘Buzz Sky Blue’ – a compact and easy to grow dwarf buddleia with deep-blue flowers. Suitable for small gardens and containers. H x S: 1.2m x 1.2m
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). H x S: 4m x 4m
Frequently asked questions
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 invasive plants, but if pruned and maintained in the garden they should not cause a problem. Buddleia can make a stunning addition to your garden, as well as producing flowers full of nectar for pollinating insects.
Can I move a buddleia?
Buddleia are tough shrubs and should survive being transplanted. The best time to move a buddleia is in March or around mid-autumn when the foliage has died. Cut the buddleia back and water well the day before transplanting. Then dig it up, move to a well-prepared planting hole and water thoroughly.
How fast does buddleia grow?
Buddleia is a fast-growing shrub that can put on a couple of metres of growth or more in a year, but it can be pruned back to a low framework of stems in early spring. Grown from seed, it is even possible that buddleia may produce flowers in the first year.
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