If you’re looking for a plant that will make your garden stand out, consider the seven-son flower, an unusual shrub that makes a splash twice each year.
In late summer, it has delicate and fragrant white flowers. A few weeks later it seems to bloom again, this time with bursts of red. They are not actually flower petals but the sepals that cradle the fruit. The long-lasting sepals gradually turn red as the small fruits ripen.
“It’s a plant you won’t find on every block,” said Spencer Campbell, Plant Clinic manager at The Morton Arboretum in Lisle, “and it won’t fit in every yard, either.” Seven-son flower (Heptacodium miconioides) is a tall, sprawling shrub that might be better thought of as a small tree, growing 15 to 20 feet high and wide.
“The bees love it,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic, who enjoys a thriving seven-son flower shrub in her own yard.
The name comes from the arrangement of the flowers in clusters of seven, with several flower clusters grouped together. The large green leaves have no distinctive autumn color, but the bright sepal show makes up for it. Older bark is whitish-tan and peels in strips for winter interest.
Seven-son flower is a relative newcomer to the Western gardening world with an interesting history. Native to China, the plant only became known to science in 1907, when plant explorer E.H. Wilson collected a dried specimen. Not until 1980 did another expedition bring back living seeds to the United States and Europe.
The seeds were distributed among botanical gardens, including the Arboretum, where the tree can be enjoyed in the China Collection. Soon seven-son flower entered the nursery trade, mostly for the sake of its dainty, fragrant late-summer blooms.
Seven-son flower is generally hardy in USDA Zones 5 to 9, but occasionally loses a branch to severe winter cold. “It does best in very well-drained soil that is somewhat acid,” Campbell said, but it also can tolerate more alkaline soil and clay soil. It needs full sun.
Because the flower buds are not formed until spring, this shrub can be pruned during the winter dormant season. Cutting it back to the ground every few years — known as rejuvenation pruning — can help control its size and sprawl.
With a seven-son flower shrub in your yard, you’ll have fragrant flowers to enjoy on late summer evenings. In the fall, when leaves are beginning to fall, you’ll have an unusual display of rosy red.
“For those who want something different, it can be a spectacular plant,” Campbell said.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.
