A Gardening Journal

The Bestest Season Ever: Yellow-flowered Spicebush

Calycanthus floridus Athens 062715 640 

 

Flowers of Calycanthus are such appealing oddities. Their rosettes of thick but narrow tepals have an almost marine look, like sea anemones on a dry-land holiday. 

 

Calycanthus floridus Athens 062715 closer 640

 

The flowers are curiously structured, in that the sepals and petals seem identical, hence the term "tepal." They are oddly sturdy, with none of the precious fragility of petals of roses, say, or tulips or cannas. Instead, they almost seem made of a soft form of cardboard, or a stiff kind of felt. Flowers of the straight species of Calycanthus floridus are an unusual brown-burgundy; this is the 'Athens' cultivar, whose flowers are cool yellow-green, like lime sherbet.   

 

Even upon close look, the flowers remain puzzling. Instead of a more typical prominence of stamens and pistil, there's another rosette, much smaller and with a fractal vibe. Dull yellow pollen stains the tips of the rings of thick stamens—the inner ones are shorter, and are still expanding and unfurling—while the short, brown-tipped pistil squats at the very center. 

 

Calycanthus floridus Athens fingers flower 062715 640 closeup

 

At whatever size, all the flower's parts seem big-boned. The tepals never reflex outward far enough to fully expose the interior of the flower: Calycanthus certainly wouldn't be pollinated by butterflies. Rather, like at least two other big-boned flowers—magnolia and lotus—beetles are the intended pollinator. They can muscle through the over-arching tepals, and may also appreciate the cover from aerial predators as they forage for pollen. And the stubby thick stamens and pistil can handle any amount of rough-and-tumble from these sometimes large insects.

 

As is typical, the glands that produce the powerful fragrance aren't visually discernible; even so, the scent is among the most penetrating of any hardy flower. You'll smell a blooming Calycanthus long before you see it: A shrub in full flower can perfume an entire garden, especially on a still evening. Considering that the flower's interior remains more-or-less hidden, the chief attractant for pollinators is probably that same unusually strong fragrance. Lucky us!

 

The fragrance of flowers of the straight species can vary bush to bush, from none to vinegary to sweet and fruity; that of the named cultivars such as 'Athens' is definitely the latter. It's as much a pleasure to experience the fragrance during the many weeks of the flowering season as it is year by year, when the Spring garden suddenly takes on the scent of tantalizing fruits—strawberry? banana? pineapple?—that would never be provided so early in the season by those plants themselves.

 

 

Here's how to grow this uniquely fragrant shrub:

 

Latin Name

Calycanthus floridus 'Athens'

Common Name

Yellow-flowered Carolina allspice, yellow-flowered spicebush

Family

Calycanthaceae, the Spicebush family. 

What kind of plant is it?

Hardy deciduous shrub.

Hardiness

Zones 4 - 9.

Habit

Upright branching stems of starter plants suggest a verticality that is soon fully countered by the shrub's strongly stoloniferous habit. Stems emerge frequently from the far-reaching underground roots, creating large and sometimely quite sparse colonies with an overall mounding habit unless a narrower footprint is maintained. See "How to handle it," below.

Rate of Growth

Medium for growth above ground; in favorable conditions, outward spread of the stolons can be fast.

Size in ten years

Size depends on exposure to sun: In deeper shade, colonies tend to be taller but scrawnier; in fuller sun—but without being stressed by dry soil—they tend to be denser, broader, and a bit less tall. In such sunny circumstances, a ten-year clump might be expected to be six to nine feet tall and ten to twelve feet across.

Texture

Fairly full when growing in full sun; more open and, even, gaunt when growing in increasingly dense shade.

Grown for

its flowers' fragrance: Fragrance can vary dramatically in seed-grown shrubs, from none to an "off" vinegar note, to more and more penetrating degrees of a striking fruitiness that will remind some of strawberry, others pineapple, and still others banana. The fragrance of flowers among individual shrubs of a given named form is consistent—cultivars are propagated by division or cuttings, not from seed—as well as pleasing. I guess none of the unscented or unpleasantly-scented forms were deemed commercially viable. I haven't been able to determine whether certain cultivars are notably more fragrant than others. See "Variants," below, for the must-have cultivars.

 

its ease of culture: Calycanthus isn't normally bothered by diseases, or by browsers with any number of legs from four on up. This immunity to browsers is probably a direct result of the pleasantly spicy fragrance released, not just by the flowers, but by stems and leaves and roots if they are bruised, broken, or crushed. Unlike the shrub's floral fragrance, which can penetrate a whole garden on a hot still evening, the fragrance of the shrub's undisturbed vegetative growth is not evident. Merely brushing up against the foliage is not sufficient for release—unlike, say, the astonishingly strong fragrance of the all-too-accurately named lemon bush, which seemed to leap out with almost predatory glee in response to the merest fingertip drawn lightly across a leaf. For a strong hit of fragrance from Calycanthus growth, your chosen shoot and leaf will need to be slain, as it were, by your focused attack. Snap a leaf into two and then four, then bring it near your nose. Pulling up unwanted root shoots (see "How to handle it," below) brings an unexpected hit of fragrance, as roots that connect back to the colony are severed and, occasionally, the bark of the shoots is stripped when a given yank-out takes more oomph than expected.

Flowering season

There are two phases. The first is in Spring, as buds that were formed the previous Summer and Fall mature. New buds that form on new growth in Spring and early Summer can also flower that same season, creating the second phase of flowering: scattered individual blooms well into Summer. Then, flowering ceases even as bud production continues—making possible the flowering of next Spring.

Color combinations

The green foliage goes with anything, as does the flowers' greenish yellow. 

Plant partners

To limit the hassle of the outward-bound growth's invasion of neighboring plants that are lower, grow Calycanthus amid woody plants that are clearly taller, whose habit is loose, and whose cast shade is only dappled not dense. Because Calycanthus can grow to six feet and higher, these overstory plants need to be twice that tall at a minimum if they aren't to look swamped outright, or just barely holding their noses above high water. A grove of the full-size forms of Taxodium or Metasequoia casts just the bright shade that Calycanthus enjoys, while the trees' feathery foliage is a dramatic contrast. I've planted the yellow-needled Metasequoia 'Ogon' amid my colony of 'Athens'; I'll prune the "meta" into a cone or column, both to control overall size and to help it retain foliage at the same level as the upper flowers of 'Athens'.

 

Some other taller partners: If you live where pure stands of pine trees occur, the stage is already set for introduction of colonies of Calycanthus. Oaks typically cast a high dappled shade, and form roots that act as if they are sparse and deep—hence the near universal suitability of Quercus as the canopy for shade gardens, including any with a colony or two of Calycanthus. If you have one of the trees that produce root shoots—Paulownia, Populus, and Sassafras are just a few—groves are almost inevitable. Calycanthus could spread outward right along with them.

 

Underplant or fore-plant only with plants that can, either, spread outward faster than Calycanthus, or form growth that is so dense, enduring, and shade-tolerant that emerging Calycanthus shoots are not a threat. Liriope spicata comes to mind first—not least, because its narrow grassy leaves are such a good contrast, and because its growth is almost scarily vigorous and, so, effective as a groundcover. Plus, it doesn't need to be groomed in the Spring, which would be tricky and even tedious amid the extensive vertical stems of a mature colony of Calycanthus: the new crop of foliage emerges above the now-flattened old crop readily, hiding it quickly in the process. 

 

Pachysandra procumbens would be another choice if you could plant enough of it so that the Calycanthus doesn't outrun it. (And if you couldn't, Pachysandra terminalis would be even more practical, if less distinctive.) So would sweet woodruff, Galium odoratum. Dwarf bamboos are certainly dense, tolerant, and fast-spreading enough, but would be a maintenance nightmare in that their old growth needs to be cut to the ground each Spring; it doesn't flop to the ground on its own. If you were committed to restraining the outward march of Calycanthus—or to thinning its growth with ascetic discipline, you could keep the colony open enough to welcome underplanting with the ornamental grass Hakonechloa; the contrast with the dark Calycanthus leaves would be shiveringly good. A fern such as Dennstaedtia could be another underplanting for Calycanthus: Its shallow rhizomes can grow outward as fast as those of Calycanthus, so it can access at least the bright shade it thrives in. Plus, the laciness of its light-green fronds is hard to top; what a vivid pairing they would be with the dark green, smooth-edged and (if you plant 'Michael Lindsay', see "Variants," below) so-shiny Calycanthus foliage.

Where to use it in your garden

The shrub's commitment to sending out far-reaching shoots is firm, and is the most important determinant of partner plants (see above) and congenial sites. Calycanthus is definitely easiest in larger scale and informal settings, where the shrub can form colonies as large as it wants. This often relegates it to a property's wilder periphery—open woodlands near fresh water are ideal—where the look is free-for-all.

 

But few gardens have such luxury of either overall size or larger planting areas where shrubs and trees tussle among themselves. To use Calycanthus in more compact, intensively designed and maintained settings, look first for sites bounded by any combination of mown grass, paving, or building foundations. Each will limit colony expansion but, because outer stems from the colony will extend outward, not just upward, growth could spill out onto paved or grassy areas by a foot or two. Calycanthus, then, isn't the shrub to grow by paving that is less than five or six feet wide.

Culture

Full sun to shade. Growth is more dense and floriferous when the shade is no more than dappled. When sited in full sun, growth is usually more compact overall; as shade becomes fuller, growth becomes taller as well as more open and even scraggly, and with lessened flowering. 

How to handle it: The Basics

This hardy shrub can be planted from Fall to Spring whenever the soil is workable—and any time when in leaf Spring through Fall when sufficient water for establishment can be provided. Unless your climate or specific site is unusually hot and dry, or the soil is shallow, supplemental watering isn't necessary past the period of establishment.  

 

Formative pruning isn't needed, but shrubs can be pruned back—mildly or even radically, right to the ground—to control size. Do this immediately after the big Spring flowering flush is done, so that new stems have plenty of time to form the buds that will mature and then emerge as full-on flowers the following Spring. To control spread at any time, chop between a root shoot and the center of the colony, then pull up the offender. If needed, pot these "yanks" up for friends or plant sales—or transplant them immediately to their desired new locations.

How to handle it: Another option—or two!

The crop of Spring flowers is early enough that branches can be cut, brought indoors, and forced. As usual, unless your set-up for forcing is unusually helpful (cool and brightly-lit, to winningly simulate an earlier-than-usual Spring), you'll probably be able to bring stems into bloom only a few weeks ahead. But even if just a few flowers force, their fragrance will perfume a room. 

 

Of course, you could also enjoy flowering Calycanthus branches indoors whenever the shrubs are in bloom in your garden. Because the flowering season is so long—two months, even three—this means that, forced or not, you can enjoy flowers indoors for nearly a quarter of the entire year.

Quirks & special cases: 

Thanks to the tepals' sturdiness, a single flower can be plucked and placed directly in your buttonhole to last the day as a fragrant boutonnière.

 

Although the shrub is floriferous, and flowers appear over many weeks, only a scattering of the bizarre pendulous seed pods develops. Despite this shrubs' being native to southeastern North America (although it thrives from Florida to Newfoundland), are necessary pollinators still scarce? Or are flowers not self-fertile, so that planting of multiple shrubs is needed? Or is sparse fertilization simply this shrub's modus vivendi? The pods hang from the branches as if by curved tail-like stems, and look like mummified bats or mice that have been cruelly strung throughout the shrub. Ghoulishly cool! The seeds, too, are fragrant: This species doesn't miss a chance.

Downsides

In my experience, all forms of Calycanthus are enthusiastically stoloniferous, making these otherwise essential shrubs a challenge whenever included in mixed plantings with any neighbors that are smaller. In such circumstances, count on severing stray runners and extricating them. I do this in early Spring, so that I can lift neighboring clumps whole-hog as needed and reset them without impairing their Summer performance. My colony of 'Purpureus' is so happy (in rich moist soil and part shade—how could it be otherwise?) that such runner extraction from adjacent obediently-clumping forms of Hydrangea and Spirea is an annual task. 

 

See "Plant partners," above, for more practical combinations. 

Variants

Calycanthus floridus is such an easy-care, high-impact shrub that few gardens should be without at least one cultivar. This functional and aesthetic desirability—plus the positive for gardeners in eastern North America, where the shrub is native and, therefore, even more well-suited to prevailing conditions—means that new forms are all the more likely to be noticed as well as brought to market.  

 

There are eight named forms and counting, and they are so distinctive that four are likely to merit a place in your garden: 'Athens' has yellow-green flowers; 'Purpureus' has typical burgundy flowers but its leaves are blushed with purple, especially on the reverse; 'Edith Wilder' has glossy green leaves and larger (to two inches) flowers with exceptional fragrance; and—perhaps most desirable of all—'Michael Lindsey', which has the species' fragrant burgundy flowers but with leaves so strikingly dark and shiny they seem varnished just for your viewing pleasure. Any form with bright yellow flowers would be a sensation—as would any whose foliage were pale or strongly variegated, so as to highlight the (usually) dark flowers. Given this shrub's ability to produce new forms spontaneously, hope for these ultra-glamourous forms' emergence doesn't seem unrealistic.

 

Happily, some extremely garden-worthy forms of Calycanthus have also emerged as result of direct human intervention, via hybridization of Calycanthus floridus with its asian cousin, the redundantly-named Sinocalycanthus chinensis (which is now known as Calycanthus chinensis). These hybrids are hardy down to Zone 5—Calycanthus chinensis is hardy just to Zone 7—yet retain the characteristics of C. chinensis: larger leaves, reliable yellow Fall foliage color and, most importantly, stunning large flowers. These are two and three times the diameter of those of C. floridus, which makes them as broad as four inches, the size of those of many a rose or camellia, or the smaller-flowered forms of magnolia. Three hybrids are readily available: Flowers of 'Venus' are milky white with yellow and pink blush at the center; those of 'Hartlage Wine' begin burgundy and fade to rose. 'Venus' is reported to be fragrant; 'Hartlage Wine' is not. 'Aphrodite' is a more recent hybrid, and is billed as 'Hartlage Wine' plus fragrance and a more generous amount of reblooming. Wow!

 

Nomenclature for these plants is still shaking out; I've seen Sinocalycanthus chinensis 'Hartlage Wine', Calycanthus raulstonii 'Hartlage Wine', and x Calycanthus floridus 'Hartlage Wine'. Just go by the cultivar name itself.   

 

With the excellent cultivars just of C. floridus, plus one ('Aphrodite' first) or two of its hybrids with C. chinensis, it wouldn't be overkill for a single to garden to have three to six colonies of Calycanthus. All the forms are stoloniferous, so a garden with multiple of colonies must have a certain size. To date, I grow just 'Athens' and 'Purpurea'; at the minimum, 'Michael Lindsay' and 'Aphrodite' await. See "Plant partners" and "Where to use it," above, for suggestions where Calycanthus colonies work well, and with what companion plants.

Availability

On-line and at specialty retailers.

Propagation

By severing root-shoots from the mother colony almost any time they are leafless, i.e, from mid-Fall to early Spring. Simply chop down with your shovel between the shoot and the main mass of the colony, then reach around into the soil to locate the severed end of the root that is leading to the shoot. Place your shovel or pitchfork tines underneath the root and lever upwards to lift a larger portion of the root mass from the ground. If your soil is loose enough and/or your grip is strong enough, you can then free the rest by yanking. Plant these bare-root sections right away, at least as deep as they were so that they don't wobble free. If you do this in the Fall, further care (such as watering) isn't usually necessary. Provided your chosen site has the preferred dappled shade and at least reasonable moisture, the young shrubs will be self-reliant from Spring on.

 

Reasonably-mature cuttings from new shoots—those that show gray-brown wood, not just the green of "soft" cuttings—are reported to root well, too.  

 

One of the reasons that some cultivars arise from natural variation instead of hybridization is that seedlings can show marked difference  from the parents. With naturally-occuring Calycanthus cultivars—'Athens' or 'Michael Lindsay' in particular—those differences can be thrilling. By the same token, though, any given seed-grown individual is just as likely not to possess desirable qualities in, say, flower color or fragrance, or Summer and Fall displays of foliage. Named cultivars are always propagated by division or by cuttings, but the species can also be propagated by seed. When purchasing the species, then, try to do this only when plants are in bloom, so that flower color and fragrance can be confirmed; you won't be able to assess Fall foliage color at the same time, alas, so go for fragrance.

Native habitat

Calycanthus floridus is native from Virginia to Florida. "Floridus" doesn't refer to Florida at all but, rather, refers to the profusion of (the Spring flush) of the shrub's flowers. (The word "florid," meaning elaborate or ornate, has a similar connotation of a bountiful display.) 

 
 
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