Most allotment sites give a home to a Buddleja or two. The common Buddleja (which should be spelt with a J, not an I) is Buddleja davidii, which naturally occurs in central China and was only introduced into gardens at the very end of the 19th century. It’s a great plant to attract butterflies and other pollinators, flowering in July and August at just the right time for summer butterflies like Peacock and Painted Lady. Allotment Buddleja are often self-seeded volunteers from tiny, winged seeds blown in on the wind from local gardens or waste-ground. The colour of the flowers of these volunteers is usually lilac, mauve, or occasionally white, typical shades for feral Buddleja. These pastel shades are the same as found in the wild populations back in its native China.
Buddleja has a reputation as an opportunist weed, and as a bit of a thug too – undeservedly so, as it is not actually considered a serious invasive in the UK. And it’s such a common sight, we tend to forget there is much more to the genus Buddleja.
Selectively bred cultivars have been around for a century, but recent years have seen an explosion on breeding programmes, and now there are over two hundred recognised garden cultivars and hybrids. Many of the most recent cultivars have been selected to be tiny, as little as 30 cm tall. Sterility of very low seed-set has also been a goal of breeders. The colour palette has increased too, and the colours are becoming more intense.
There are about a hundred different species of Buddleja, from Africa, Asia and the Americas. About thirty of these can be grown in temperate gardens. Some require a little more shelter, but we are lucky on our site. Court Oak Road Allotments is on a south-west facing slope, with the top of the site often several degrees warmer than the bottom in the winter. This aspect means some of the more exotic species can be grown quite successfully. Having access to an allotment has afforded me the space to trial new varieties, develop some of my own cultivars and hybrids, and to conserve unfamiliar Buddleja species.
The garden centres are full of new Buddleja hybrids, many of which are much smaller than normal Buddleja. Most of these mini-Buddleja are very poor plants, little more than a novelty or gimmick. And I’ve found most cannot take any exposure, with our windy location too demanding for their weakened constitution.
As well as the commercial plants, I’m also trying out some of my own plants I’ve grown with seed from controlled crosses. Waiting for these seedlings to flower makes July a particularly exciting month, the anticipation of seeing a flower for the first time. My goal has been to get darker colours and new forms. This is not as easy as it sounds, as the weak pastel shades are genetically dominant, and fixing recessive traits quite often also breeds in problems and weaknesses. For example, I recently removed a fine, purple-flowered plant because fixing the deep colour had also reduced the buds’ resistance to insect attack. Others have been more successful, and I’m especially pleased with two, a dark blue-purple and a deep pink (shown in photos). These two have no issues: they have reasonable vigour, good upright habits and are very floriferous. They are also easy to propagate, and the cuttings come true.
I’ve also managed to grow a number of seed-sterile hybrids, a property that is increasingly desirable given Buddleja’s reputation and a legal requirement for garden cultivars in New Zealand and some states of the USA.
Species of Buddleja that can be grown on a site like Court Oak Road include the South American B. globosa with little orange golf-ball shaped flowers, and B. alternifolia (Weeping Buddleja) from China. These two flower primarily in the late spring, and their flowers are gone by July. One less familiar species in flower during this month is <i>B. forrestii</i>, a large species from southern China named for the famous plant-hunter, George Forrest. Traditionally, <i>B. forrestii</i> was seen as a semi-tender species, but with climate-change and our favourable aspect, this can now thrive on our site. B. forrestii looks rather different with large thick leaves and bigger flowers (see photo). I grew mine with seed from the mountains of south Sichuan I was able to source directly from China.
I also grow some other less well-known Chinese species, and in flower now are B. albiflora, B. fallowiana and B. myriantha. Although relatively rare, these are not strikingly different from B. davidii. I am grateful for having access to an allotment because I would not be able to grow and study such a range of Buddleja in my own modest garden.
If you would like to know more, please do visit my website – The Buddleja Garden.
Andrew Large
