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Last updated on January 21st, 2020
Buddleia shrubs are known for their abundant spires of flowers, flowers that bring to the garden a scent of honey and amply butterflies. These flowers are rich in nectar, so much so that they bring to any wildlife garden up to 22 native species of British butterflies. It is for this reason that the plant is commonly referred to as the butterfly bush. There are even compact varieties today that can be used for container growing in smaller gardens. The butterfly bush is very strong and can handle coastal conditions with the heavy wind and salty air which makes them perfect for just about any garden.
A native of China, there are different varieties, the largest of which will reach up to four meters in height but thankfully there are dwarf varieties and hybrids which are more compact as already mentioned. They will survive with temperatures as low as -15 degrees Celsius making them perfect for British gardens so long as they have a position with good sunlight.
It is best to plant them alongside other butterfly sustaining options such as ceanothus. You want to take particular care to deadhead each of the shrubs after they have flowered so that the seeds don’t end up in other landscapes or areas of your garden. They will spread prolifically if you fail to deadhead properly.
You should plant a new butterfly bush as soon as the worst of the winter weather is over usually late spring when the soil starts to warm. Daylight temperatures should be maintained around 10 degrees Celsius with nighttime temperatures dropping no lower than 0 degrees. Once the weather fits these parameters you can position your plant at the same level within your garden as it was in the pot. Water it well while it is getting established unless of course, the weather is doing that for you naturally but it’s usually best to water regularly while the plant gets established and has a limited root system. If you are growing in containers use a loam-based potting compost such as John Innes No 3 and water the plant well after you have planted for the same reason. Buddleia grown in pots will need water regularly, especially through the summer.
The butterfly bush is incredibly easy to grow and you will see it growing happily around factories or next to railroad tracks in a self-seeding fashion. It usually doesn’t care about climate and it has no preference for soil type which is why it will successfully growing just about anywhere.
Prefers full sun but will grow well in partial shade
It does best in full sunlight but it can handle partial shade. Just make sure that you have an area in your garden where you can give you a butterfly bush a few hours of sun every day and it will flower just fine.
Very drought tolerant once established
The butterfly bush is resistant to drought so once it gets established you won’t really have to water it unless the weather turns particularly dry in the summer. During the summer if there is a drought you can water it thoroughly but just do this once a week and it should do just fine. In spring if we have periods of low rainfall, you might have to water it a little more. Springtime is when the butterfly bushes do most of its growth so it’s important to make sure it doesn’t dry out during the Spring. With established plants in the ground, this is usually not an issue but it is particularly important with container-grown plants where they can quickly dry out. Growing in containers is perfectly fine so long as you pick an appropriately-sized plant and make sure the soil never dries out. Don’t forget you can now get dwarf buddleia which are perfect for growing in pots.
Grows well in any well-drained soil type
These plants will thrive in any soil too long as it is properly draining. They will do their best if you have a lime soil or chalky soil. In order to sustain the plant over winter make sure that it doesn’t sit in wet soil for too long. If you do plant in a position that can get a little wet over winter then dig plenty of grit in the soil to help improve drainage.
Butterfly bushes do not need regular feeding or any type of food unless you have been growing them in containers in which case you should feed them in the springtime just once every year. If you feed plants in the ground it will encourage a prolific amount of foliage but you won’t get as many flowers and it’s the flowers that really bring the butterflies and the beautiful scent to your garden.
In terms of long-term maintenance, one of the biggest things you’ll have to do as mentioned is deadheading. Deadheading is important because it prevents the flowers from converting to seeds and then spreading to unwanted areas and more importantly it encourages more flowers. Your plants only have a finite amount of energy and they will allocate that energy where it is needed most. It will continue feeding energy to dying flower stalks which are going to seed if you don’t deadhead. By deadheading, your plant will send that energy into new growth instead and more flowers.
Winter protection for container-grown plants
If you are growing in containers position the plants in a sheltered area for the wintertime and consider wrapping the pot in bubble wrap or fleece. It is best to, come springtime, remove the top few centimetres of compost every year and replace it with new compost. This will help the dwarf varieties to grow stronger year after year. If you are growing a large variety in a container be advised that it will only survive a few years before it has to be moved to a new pot as most varieties are very vigorous and fast-growing.
If you have to repot your butterfly bush because it has become rootbound, buy a pot that is slightly larger than the container in which it is growing currently. Larger variety will not last for more than 2 years when in a pot and at some point will need to be transferred to the ground directly if you are to continue with them. This is why we only recommend planting a dwarf variety in containers.
Pruning Davidii Varieties
Pruning should be done regularly and buddleia responds well to pruning and can be cut back very hard if needed. Cutting back your butterfly bush regularly will encourage it to remain vigorous and compact in shape. If you don’t prune it will get straggly and you will have fewer and fewer flowers appearing only at the very top of the stems. By comparison, if you prune regularly it will encourage additional flowers lower down on the plant as well as maintaining a manageable size. The traditional Buddleia Davidii will produce flowers on the newest of growth which means you should hard prune it at the beginning of Spring and cut it very close to the ground, maybe to 2-3ft or even lower if needed. You should only do this after the worst of the winter weather has passed in spring. Try to keep a solid framework of at least five main branches to ensure additional flowers that same year.
Pruning Buddleia alternifolia
If you are growing the Buddleia alternifolia, you will have to prune after flowering at the end of summer. If you prune this type of butterfly bush in the spring you won’t get any flowers the following summer. With this one you don’t have to do a hard prune, just cut back any stems that have already flowered or no stems that are not flowering successfully. If the plant has become overgrown and you need to do a hard pruning, do it in stages. Start one year by cutting back half of your shrub. The following year cut back the other half of the shrub in the spring. This will help to avoid overstressing the plant.
Pest and diseases
These plants are typically resistant to bugs and diseases but on occasion, you might have to deal with something. In terms of pests, one of the biggest issues you might face is that of spider mites. Almost invisible to the naked eye you will probably see the tiny orange-red mites spider web before you see the actual mites. However, if you suspect you can simply hold a piece of paper underneath the branch and shake that branch to see if any bugs fall onto your paper. You can spray your plants with insecticidal soap or a pesticide.
As with most garden plants, aphids including greenfly can be a problem sucking the sap from the foliage and causing the leaves to curl, this usually affects young fresh leaves. These are best treated as soon as you notice them by spraying with pesticides
There are two diseases that you might have problems with. The first is mildew. This happens when the temperatures get colder and the leaves stay wet. You will see mildew growing and furry patches underneath the leaves and you might also notice that the tops have turned yellow or brown. If you see any stems that have been particularly impacted by this mildew, just remove them and dispose of them. You can help reduce the risk of this mildew by cutting back your plant if it’s growing too closely together, or thinning out the middle of the plant to help increase air circulation. Dead leaves and weeds on the ground need to be removed immediately. We also recommend spraying with a fungicide as soon as you notice mildew.
Root rot caused by waterlogged soil
On occasion, the other issue with what you might contend is that of root diseases. You might notice that your leaves are turning yellow and this could mean your plant has a root disease which is making it impossible for the roots to get the nutrients they need. This usually happens when your plant gets waterlogged and you can improve the drainage to help with that and apply a fungicide. Root diseases are fatal to butterfly bushes so make sure that the plant is never waterlogged and if you see the telltale signs, treat your plants immediately.
Some of our favourite varieties
These plants come in a variety of sizes and flower colours. You can find varieties that have flowering spires with narrow shaped leaves, woody stems, and more. While there is a range of colours including all manners of purple, red, pink, and white, butterflies prefer the Lilac coloured flowers over maroon or white.
Types of buddleia
The original version of this plant is called Buddleia Davidii of which there are many varieties and it is generally a vigorous bush that if not well maintained will become very messy. It produces flowers in August and will self-seed particularly quickly. For that reason, it can be invasive if you don’t tend to it regularly. This is done with deadheading which only takes a few minutes to quickly remove spent flowers when needed.
Newer cultivars are less invasive and more compact making a perfect for containers or smaller gardens. That said you should pick the variety based upon the suitability of your space but some of the dwarf varieties such as the Buzz varieties are excellent.
Buddleia Davidii ‘Black Knight’
Buddleia Davidii ‘Black Knight’ is known for the fragrant rich, Indigo flowers. This is drought resistant and very strong with a maximum mature height of 3 meters. If you want to grow this variety but keep it smaller you can prune it regularly to ensure a compact and it responds very well to hard pruning.
Buddleia Davidii ‘White profusion’
Buddleia Davidii ‘White profusion’, as the name suggests, offers spires of white flowers in a bushy form. A slightly larger cultivar it can reach up to four meters but can be less effective as attracting butterflies than other varieties.
Buddleia Davidii ‘Pink Delight’
Buddleia Davidii ‘Pink Delight’ has pink flowers that are orange-eyed. The full plant will reach a maximum of 4 meters so is another large variety.
Buddleia Davidii ‘Royal Red’
Similarly, Buddleia Davidii ‘Royal Red’ is the same size but the flowers are heavily scented and bright red in colour.
Buddleia Davidii ‘Monum’
Buddleia Davidii ‘Monum’ is a more compact variety perfect or smaller Gardens as it reaches only 1.5 meters in height at full maturity, however its not a true dwarf variety.
Buddleia Davidii ‘Nanho White’
Likewise, Buddleia Davidii ‘Nanho White’ offers compact, white flowers that will reach no more than two metres in total.
There are hybrid varieties from which to choose as well. Buddleia Lochinich Is a hybrid variety that has silvery-grey leaves with lavender-blue flowers and reaches a height at full maturity of 3 meters.
Buddleia alternifolia ‘Argentea’
Buddleia alternifolia ‘Argentea’ is a hybrid that grows in a sweeping fashion. It has velvety silver leaves mixed with highly fragrant flowers which are bright pink and bloom from July through August. A slightly larger variety will reach a maximum height of 3.5 m.
Buddleia alternifolia ‘Unique’
Buddleia alternifolia ‘Unique’ is a more compact shrub that has longer more fragrant flowers in a lilac colour. If you don’t want to worry about deadheading and you want to prevent the plant from spreading into other areas of your garden, this is a sterile plant so it won’t self-seed and spread the butterfly bush to the rest of the garden. You will get flowers from July through October and this variety only grows to around a meter tall so is small in comparison to most other varieties.
Buddleia Buzz is another dwarf variety that’s perfect for containers. You can choose several colours from among the store variety such as sky blue, Ivory, or magenta. The colours are named as such so obviously, if you want sky blue colours, you want the sky blue variety.