These surprisingly hardy South African perennials light up the border with their fiery colors
by DANIEL J. HINKLEY photography by DAVID McDONALD
OF ALL THE FLORISTIC REGIONS OF THE WORLD, none surpasses southern Africa in diversity. Among the estimated 9,000 plant species native to the southerly tip of that continent, many have secured a presence in the collective botanical consciousness of Western society. The hybrid pelargoniums and gladioli, though considerably altered by breeding, are familiar to virtually any consumer, and keen gardeners will recognize many more generic names from the region’s immeasurable inventory of species—Diascia, Dierama, Eucomis, Freesia, Kniphofia, Phygelius, and Schizostylis, to name just a few. Along with these horticultural treasures, the genus Crocosmia has won the devotion of gardeners in both North America and Europe.
Few other garden perennials provide such a saucy and torrid display of flowers in the dog days of summer. The long-lasting tubular flowers, in a spectrum of spicy colors, erupt from clumps of pleated green or bronze irislike foliage in mid- to late summer, held on erect two-and-a-half- to five-foot stems. Given full sun and well-drained fertile soil, they are dependable border denizens.
The name Crocosmia comes from the saffronlike fragrance of the dried flowers when they are placed in warm water (krokos is the Greek word for both crocus and saffron; osme means odor or fragrance). This shared olfactory trait isn’t surprising, since Crocus sativus, the source of culinary saffron, and crocosmias both belong to the iris family (Iridaceae). Taxonomically, the genus has been known in the past under different names, including Tritonia and Montbretia.
There are nine species of Crocosmia, with eight native to southern and eastern Africa and a single species from Madagascar. Of these, however, only four seem to have been major players in the production of the hybrids now gaining such popularity: C. aurea, C. masoniorum, C. paniculata, and C. pottsii. In the wild, the species fall into two major groups, each visited by a different kind of pollinator. South African botanists John Manning and Peter Goldblatt report that species with short-tubed flowers are pollinated by long-tongued bees, while the long-tubed species are pollinated by sunbirds. In North American gardens, the brightly colored, nectar-rich flowers are attractive to numerous bee species as well as hummingbirds.
Although crocosmias are only now becoming better known throughout much of North America, the majority of the breeding and selection work dates from the later years of the 19th century. In the 1870s, French nurseryman Victor Lemoine crossed C. aurea with C. pottsii to create the first known hybrid. This is still well known as the rambunctious and ubiquitous common montbretia, C. xcrocosmiiflora, naturalized along the coastal states of the Southeast and California.
The debate over the general hardiness of crocosmias can be traced to differing cultural practices, which produce vastly different outcomes. Most, if not all, can be considered completely hardy in USDA Zones 6 and above. It’s important to bear in mind, however, that crocosmias are more susceptible to rotting in winter from excessive wet than they are to damage by freezing. If you garden in a borderline area, consider mulching your plants after the first light frost with a dry organic material such as sawdust or woodchips—their hydrophobic properties will repel excess moisture while insulating the bulbs from extreme temperatures. Crocosmias are also extremely well adapted to container culture, and can be easily maintained in pots for many years. Keep the containers cool and dry in winter and water the plants regularly during the growing season. –D.J.H.
The montbretia’s relatively small burnt-orange flowers provide a fascinating glimpse at the way in which crocosmias entered cultivation. Though charming in a simple sort of way, the plant is not reliably hardy in areas colder than USDA Zone 6. It is probably because of this relative tenderness that many of Lemoine’s 55 named selections, based primarily upon C. xcrocosmiiflora, are no longer extant. One of Lemoine’s crocosmias, however—the large-flowered C. aurea ‘Imperialis’—has influenced nearly all subsequent hybrids.
Following Lemoine’s lead, the English became obsessed with crocosmias at the turn of the last century and began creating hybrids with a more durable nature. Through the early years of the 20th century, numerous large-flowered forms appeared that remain in high demand today. Among this group, ‘George Davison’, ‘Lady Hamilton’, and the magnificent ‘Star of the East’ offer gardeners in Zones 6 through 10 large flowers in volcanic colors for a long period in mid- to late summer.
Subsequent breeding in the years leading up to World War II culminated in a group known as the Earlham Giant hybrids, many of which are still in commerce today. As their names suggest—‘George Davison’, ‘Lady Hamilton’, and ‘E. A. Bowles’, for example—they were the quintessential vanity plants of their time. Despite the fact that they were hugely expensive, they were highly popular with the gardening community in England.
Because of the lack of knowledge regarding exactly which species of Crocosmia were being used in this early breeding work, assigning the numerous named cultivars to specific species or hybrids is challenging, if not impossible. A notable exception is ‘Lucifer’, the most popular of all crocosmias in North America, thanks to its vigor, hardiness, and four-foot blast of vibrant red flowers in midsummer. In their new book, Crocosmia and Chasmanthe (Timber Press, 2004), John Manning, Peter Goldblatt, and Gary Dunlop state that it is a cross between C. masoniorum and C. paniculata.
Crocosmias grow from corms not unlike a very small gladiolus. Rhizomes spread outward from each corm to form substantial colonies over time. By observing over 80 named varieties at the Heronswood garden, I’ve realized that the length of each rhizome—in other words, the ultimate density of the colony—is an important element of overall gardenworthiness. (See “Dan Hinkley’s Favorites,” below.) Those cultivars with shorter rhizomes produce impenetrable, weed-smothering mounds, while also providing a more concentrated floral punch within a smaller area.
The hues of most cultivars range from butterscotch and tangerine to sizzling bicolors of scarlet and orange. Pink and pure white, both highly coveted, have so far eluded breeders, though progress has been made. Cultivars such as ‘Culzean Peach’ and ‘Severn Sunrise’, which moderate the characteristic crocosmia flame to near-pastel tones, represent stages in the quest for a true rose-colored selection.
Crocosmias contribute much-needed textural relief to the late-summer border by virtue of their emphatically vertical silhouette.
DAN HINKLEY’S FAVORITES
‘Coleton Fishacre’: Similar to but taller than ‘Solfatare’, with burnished leaves to 3 ft. and striking flowers of melon yellow.
C. masoniorum ‘Blaze’: An extraordinary selection with quantities of sizzling orange flowers on compact stems to 2 ft.
‘Culzean Peach’: Apricot-colored buds open to orange flowers blending to peach on the petal tips, on branched racemes to 2.5 ft.
‘Lucifer’: Considered one of the hardiest, this garden stalwart provides vertical blades of translucent green to 4 ft. and an explosion of mandarin-red flowers.
‘Olympic Sunrise’: My seedling selection from ‘Solfatare,’ with handsome dun-colored foliage and bicolor orange flowers with yellow throats.
‘Queen of Spain’: A large-flowered selection in sizzling orange red, with blossoms borne along branched stems to 3 ft.
‘Solfatare’: A classic garden hybrid selected for bronzed foliage to 2 ft., which provides a good contrast for its rich butterscotch-colored flowers of moderate size.
In August and September, their torrid colors complement yellow- and orange-flowered dahlias as well as the bold-foliaged cannas, while contrasting handsomely with the chilling blues of agapanthus and Salvia guaranitica.
In the wild, crocosmias revel in ample summer sun, and this trait has not been altered by hybridization. Though many assume that the genus requires lean soils, crocosmias are most content in an evenly moist soil with an adequate organic content. If grown under the correct conditions, staking will not be necessary, nor will insect pests and disease be problematic. H
For sources of plants featured in this article, turn to page 67.