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Seven-Son Flower Finally Available!
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

September 19, 1999

About seven years ago I began writing about a "new" tree that I liked, but I always had to add the caveat that no retail nursery or garden centre had it available yet. Well, finally I can report that seven-son-flower (Heptacodium) is available at the retail level, at least in southern Ontario.

The fact that it flowers in mid-September, even later in the season each year than the much-better-known rose of Sharon (Hibiscus syriacus), is just one of the plus factors this little-known tree has going for it. Now, the flowers aren't spectacular--small clusters of creamy white florets (in groups of seven--thus the name "seven-son flower") somewhat resembling small honeysuckle flowers in spring. The clusters at the ends of the branches, however, are not large--perhaps about a third the size of those on the Japanese tree lilac in June. There is some fragrance but again, not a great deal. Nevertheless, a tree with any kind of flowers in September in our climate is more than worth noting.

Heptacodium is a fast-growing tree/shrub, a native of China, which has been grown by a few nurserymen here in southern Ontario for the last seven years or so. All trees planted thus far survived the devastating winter of 1995-96, so it is obviously hardy at least in zones 5 and warmer. It is a little better known along the eastern seaboard of the US.

The bark on the trunk of mine (just 6 cm [2½"] in diameter about 30 cm [1’] up from the ground) already shows a handsome exfoliating habit during winter months--i.e. the upper "paper" layer of bark that is tan in colour peels back to reveal a darker brown colour beneath.

The tree has other attributes as well. When the flower petals have fallen, the calyces (green lower part of the flowers that normally falls with petals on most plants) stay on and continue to grow while taking on a reddish colour. This, however, is not the end of the Heptacodium's autumn colour! Soon after, fruit develop and these are of an even brighter--red to mauve--colour. They do not endure, lasting only a couple of weeks before they turn to a tan colour.

The foliage of this unusual tree somewhat resembles that of the PG Hydrangea, but is slightly larger, and thinner. It takes on an unspectacular yellow colour in autumn, but does stay on the tree late into the season.

Heptacodium (I prefer that somewhat tongue-twisting botanical name to the lengthy "seven-son flower," that accompanied the tree from its native China) is rare still today, even in China. It came to the attention of the Western world only in 1916, and was introduced into cultivation in North America much more recently by the Arnold Arboretum, Boston, and the National Arboretum, Washington, DC. They expect it will be hardy in Canadian zones 5 to 9. Possibly a better guideline is that it is likely to be hardy where PG hydrangea, sugar maple, amur privet, Virginia creeper and Vanhoutte spirea (bridalwreath) grow.

Heptacodium may be grown as either a small tree (perhaps reaching a height of seven metres [20 ft.]) or a multi-branched shrub of a lesser height. It is fast growing but mine at least, is not broad spreading. Nurserymen tell me it is tolerant of most growing conditions including wet/dry and acid/alkaline soils. Though it likes sun, it seems to take part shade as mine only gets sun until early afternoon.

And now, finally, I note some availability of this useful small tree (or shrub). In Toronto, two or three Sheridan Nurseries Ltd. outlets currently have potted shrubby plants about 175 cm (5 ½’) tall. [Presumably, as more nurseries get into the seedling production of this tree, the price may come down considerably.] If you’re looking for a nice open, wide spreading, fairly fast growing small tree or shrub, take a look at Heptacodium.

By Art C. Drysdale, 6 Nesbitt Drive, Toronto, Ontario M4W 2G3Art Drysdale is seen hourly every day on Canadas Weather Network at 23 minutes after the hour, and heard Saturdays from 9 to 11 am, with a live two-hour radio broadcast on Toronto's TALK640 (640 on the AM dial)

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