The seven-son flower (Heptacodium miconioides) is a relatively recent addition to the palette of autumn-flowering shrubs and trees. It’s an obscure member of the Caprifoliaceae family and therefore a close relative of the much better known honeysuckle (Lonicera spp.).
This species was discovered in China in 1907 by the famous botanist E. H. “Chinese” Wilson (the one who inspired the Indiana Jones movies), but wasn’t brought into cultivation at the time and had long since sunk into oblivion. It was only rediscovered in the Anhui and Zhejiang provinces of China in 1980. From there, seeds were sent to Boston’s Arnold Arboretum. The plant was successfully trialed there for several years and found to be hardy and garden worthy. By the 1990s, it was being mentioned in garden articles and has since gained more and more in popularity.
One of a Kind
The seven-son flower is monotypic: the genus Heptacodium has contains only the one species: H. miconioides. (H. jasminoides, a name sometimes seen, is considered synonymous with H. miconioides). Heptacodium means “seven-headed” because its inflorescence branches seven times, quite an unusual characteristic. The English names are derived from the Chinese name of the plant, which translates as seven-son flower or seven-son plant.
This plant is usually sold as a shrub, but will actually become a small tree, up to 25 feet (8 m) tall. It can be kept to a more shrublike height of 5 to 10 feet (1.5-3 m) in height and spread by pruning. Think of it as needing about the same pruning as a French lilac (Syringa vulgaris), removing older branches to leave room for younger ones. Since it blooms on new wood, it is best pruned in early spring.
The most striking feature of the seven-son flower is its very late bloom: August or September, in most climates. Mine starts blooming pretty much like clockwork during the first days of September. The flowers are small but numerous, with a faint scent of jasmine, and last nearly a month.
What happens next is even better: the flowers give way to small purple berries surrounded by purplish red star-shaped bracts, giving the impression the plant is blooming a second time. However, the bracts do not always show up in short-season climates like mine: frost comes too quickly.
The foliage is quite original: medium green, shiny and clearly arching, giving the plant an almost a tropical look. In climates with a long fall, they turn an attractive deep reddish purple in late autumn, but in my climate, they tend to drop off while still green, killed by early frosts.
The beige-brown bark is unimpressive in young specimens, but beautifully exfoliates as the shrub matures, revealing multicolored layers. Mature specimens can be quite impressive in the winter, with bark that vaguely resembles that of a eucalyptus (Eucalyptus).
The plant has a dense, fairly rounded shape in its youth, taking on a more arching, fountainlike appearance as it matures. It becomes quite barren at the bottom if not pruned, eventually losing most of its lower foliage as it becomes a tree. You really have to choose: if you prune it regularly, it will remain a thick green shrub, but the bark won’t be too impressive. If you let it grow, it will instead slowly switch from a shrub to a small tree, with attractive bark at the base and but foliage and flowers only at the top.
Easy to Grow
The seven-son flower adapts well to garden settings, doing well in most well-drained soils, especially if they are on acidic side, and in full sun to half shade. Although is seems to do particularly well in fairly moist soil, well-established plants are quite drought-tolerant. Since it blooms on new wood, any pruning should be carried out in the spring. You can plant it in either spring or fall.
No one knew how hardy this plant was going to be when it was first introduced and it was originally offered for zones 6 to 9. However, it has proven far hardier than that and I can assure you it is totally hardy in USDA zone 3 (Canadian zone 4) and worth trying in even colder zones, as it has been shown to survive -40˚F/C temperatures with no damage.
Where to Find One?
For a plant that was completely unknown only 15 years ago, the seven-son flower has come a long way and you should be able to find it in better local nurseries. If it’s not currently available, ask: a good nurseryman ought to be able to get you a specimen in time for planting next spring. And if that doesn’t work, try mail order.
Try seven-son flower and you’ll see: it is really quite a remarkable plant!