How to grow buddleia – and keep it blooming into autumn

·2 min read
<span>Photograph: Rex/Shutterstock</span>
Photograph: Rex/Shutterstock

The ubiquitous butterfly bush, Buddleja davidii, so fond of the cracks in our concrete world, is familiar to all, particularly those that flutter. There is, however, a world beyond the feral bush of our cities and railway lines: those with deeply scented flower spikes in pinks, deep purples, bicolours and purest whites; those that tower as tall shrubs; and those that are happy to stay small enough to live in a pot on a patio.

The place to go and see them is in the national collection at Longstock Gardens in Hampshire. If you are passing, it is well worth dropping in to peruse the many colour variations. They are laid out in a rather splendid walled garden and there will be something in flower right into October, thanks to dedicated deadheading. If you are thinking that buddleia’s pretty spires are long gone by now, then that is the secret: when roughly half the flower spike starts to brown, remove it and this will spur the plant into producing more. Once the seed starts to set, the plant considers its job done for the summer and concentrates on producing as many babies as it can for you to weed out. If you can keep on top of deadheading, you’ll have flowers well into early autumn.

This is an easy enough task if you have a pot-grown plant, but less so if yours is towering into a tree. One way to solve this is to prune back in early spring. This also encourages better flowering. Cut all the shoots back hard, to 20cm from the ground. If your spot is cold and damp, however, particularly if you are on heavy clay, then it’s worth waiting till as late as April so that new shoots don’t get frosted.

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Out of the many cultivars, my heart is set on the deep, sultry dark purples, such as ‘Persephone’ with its orange eye and deep mauve flowers, and some of the more shameless pinks, such as ‘Pink Delight’ with its honeyed scent. The white and paler lilacs are wonderful when in full peak, but you need only a few of those damp early August days and they start to look like sodden, snotty tissues as the brown spent flowers appear. Not all buddleias are created equal to butterflies; scent seems to be important and some of the sterile cultivars certainly seem to have less to offer.

For pots, try ‘Dreaming Purple’, which has a more typical lavender-purple flower with a compact, trailing habit. One of the most elegant in my eye is ‘Nanho Purple’), which is decidedly less wild-looking, growing to only 150cm tall, with silver green leaves and pendulous, rich reddish-purple flowers with orange throats. It is always adorned by bees and butterflies.

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