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Heptacodium Miconioides, the Seven-Son Flower

A berm blog update

Dave Cantwell —  September 21, 2013 — 18 Comments
PHOTO: Image of bark

The gorgeous, exfoliating bark of Heptacodium miconioides looks stunning year-round.

Are you looking for a plant that offers some “wow” at the end of the season? That particular something that offers color, and maybe even more? Here’s something on steroids: Heptacodium miconioides.

This large shrub or small tree (15 to 20 feet tall on average), native and rare in the wild in China, was successfully reintroduced to western horticulture in the 1980s, and its popularity has come to span the globe for good reason: this is not just a brilliant autumn performer—it’s a year-round beauty! I suppose we can start the story when this ornamental shrub is dormant in the winter, with its striking exfoliating bark peeling off of nearly every branch in tan, cream, or light brown ribbons or patches, revealing the underlying tissue that has developed into a wash of many colors: vertical striations of creamy white, deep yellow, green, tan, bluish-green, olive green, brown, ochre, and even rust; more so as the plant ages. But that’s just the beginning of the show.

PHOTO: Heptacodium miconioides in flower

The Latin Heptacodium means “seven flowers,” hence its common name “seven-son flower”— though that’s just the average number of flowers on each shoot.

Heptacodium are among the first to sprout leaves in the spring, and their light green color is especially attractive. Should they break dormancy in an early thaw and the leaves succumb to a return of the cold, do not fret, because they’ll start over again. This plant likes to grow. Once the leaves fill in and the warm weather settles in, you’ll have a beautiful, irregularly umbrella-shaped, dense canopy of long, shiny, deep green leaves. And suckers. Be sure to catch them in late May and cut them off, as they can easily and rapidly form straight whip-like vertical branches that mess up the plan. You may even need to revisit the suckering scene in late summer, as it simmers down and readies to bloom.

Let your Heptacodium establish for a couple of seasons into a V-shaped, multistem plant, then select three to seven sturdy stems for the plant to stand on, and cut off the rest of the stems, including the suckers. (As we’ve mentioned, this plant likes to sucker. Profusely. Even if it gets run over by an off-road vehicle—and some of ours have—it will sucker back into a strong and proper plant in one or two seasons.) They really like to grow, and with few natural (nonautomotive) pests to disrupt their progress, they’re reliably hardy in the Chicago area’s Zone 5 climate.

PHOTO: Heptacodium miconioides in fruit

It looks like it’s blooming, but this is the fruiting stage. After pollination, the sepals elongate and change from green to dark pink, becoming part of the incredibly showy fruit.

In late summer the plants begin to set up for their flower display, developing whorls of buds at the tips of the branches; these structures form bracts of seven, hence its common name, “seven-son flower.” These open progressively, until the entire plant is covered in a cloud of tiny white blooms that smell somewhat like jasmine or alyssum—a sweet scent, to be sure. As amazing as this display can be, it changes even more. As the small dark fruits (or seeds, or berries) form, the white petals fade, and the corollas (flower petals) form sturdy calyces (a calyx is a specialized petal that wraps around the fruit) that color up into reds ranging from rose to nearly purple; some are even bluish in color, which can last as late as November, when the birds will find these treats and finish them off.

But wait—there’s even more! We’ve come full-circle back to the amazing winter display of that colorful, textural, exfoliating bark. With all of this to enjoy, seriously consider placing one (or more) of these beauties in a highly visible, year-round spot in your garden.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Selecting perennials to look good year-round and weather the seasons outside our wall (and next to the freeway) has been a challenge! With its own group of microclimates and an often-harsh growing climate—including high winds and both flooding and drought conditions—cultivating the garden along the Garden Wall and Berm has been a learning experience.

PHOTO: Panoramic shot of the garden visible through and behind our sign on the Edens expressway.

The Garden section in question, located by the big Edens Expressway (northbound lanes) sign.

Originally, the design for the perennial border—which you can see trailing up and down the hill behind the big Chicago Botanic Garden sign—included Tatarian aster (Aster tataricus ‘Jindai’), which stands tall in the fall and produces clouds of small lavender-blue flowers well into late October and even November. The problem with this particular plant choice was its aggressiveness. It’s not exactly invasive, but it’s a bully: its roots spread out and then shoot up a new plant every few inches, which produce a forest of these plants. Unfortunately, they soon encompassed pretty much everything in their path. Even the hearty feather reed grass (Calamagrostis acutiflora ‘Karl Foerster’) began to succumb to this persistent tide of plants, strangling down into mere wisps of their former glory.

PHOTO: Aster tataricus 'Jindai'

A dense grouping of our problematic asters.

Manual removal of the asters was only part of the solution; we needed to find a replacement for these bad boys. In the process, we revisited the vision for this border, and decided to mix drifts of purple coneflower (Echinacea), blazing star (Liatris), and several varieties of ornamental grasses with a replacement for the original Tatarian asters.

The chosen replacement was a smooth aster cultivar, Aster laevis ‘Bluebird’, which is new to the Garden’s plant collection. It bears flowers nearly identical in color to ‘Jindai’ and can grow to the same height as well.

PHOTO: Bluebird smooth aster (Aster laevis 'Bluebird')

Bluebird smooth aster (Aster laevis ‘Bluebird’) is getting along nicely with its neighbor plantings.

Furthermore, this cultivar is more well-behaved and doesn’t spread as aggressively. Bluebird smooth aster simply grows bushier in successive seasons—a win/win situation, to be sure. The replanting process took staging and preparation that began with the removal of any grasses that would need to be relocated or divided, and these were heeled into a well-mulched bed located immediately at the site, and watered generously. Additional EchinaceaLiatris, and grasses were delivered and staged for installation. Once all of the ‘Jindai’ had been removed, it was time to plant the new group. 

The new Bluebird asters came in 2-inch pots and were notably small compared to the 4-foot-tall plants they were replacing; to top it off, these were beginning to bloom in June, so the top half of these small plants needed to be trimmed off, making them even smaller. But we were confident that these plants would be well-sited in full sun, so their potential growth was a slam-dunk.

Once the grasses were in place—Panicum virgatum ‘Rotstrahlbush’, Calamagrostis acutiflora ‘Karl Foerster’, and Sorghastrum nutans ‘Sioux Blue’—the rest of the perennials were planted, with the idea of pulling the taller Liatris more toward the middle or back of the border and allowing the Echinacea to fill toward the front. The new asters would eventually stand toward the middle and back of the bed, as tall as most of the grasses. It was important to maintain the colors placed well among the grasses, as they would be the last to bloom. Planting and mulching happened simultaneously to avoid damage to the new asters.

PHOTO: Panoramic shot of the new plantings in full bloom.

This thriving section of the replanted Garden Wall and Berm has a prairie theme: blazing star (Liatris), coneflower (Echinacea), Bluebird asters, and a variety of grasses.

That was a year ago, and the border looked fine in the fall, but the question remained—how will it look this year? We’re happy to report that the Bluebird asters are rocking it: they were already as tall in July as their neighboring grasses, and they’re filling out and ready for a spectacular fall display. Of the 3,200 plants that were either moved, divided, or planted anew, the survival rate is exceptionally high: fewer than 1 percent of the plants were lost! It’s mid-August at this writing, and the colors are popping. So, the next time you drive by, carefully check it out, and enjoy this part of a lengthy border of native beauty.


©2013 Chicago Botanic Garden and my.chicagobotanic.org