Hot Color: Crocosmia
In her book The Flamboyant Garden, award-winning author Elizabeth Sheldon comments on the tendency of many gardeners to shy away from gaudy colors in the garden in favor of classier color schemes in gray, blue, mauve, and silver. "It seems to me that...[we] have been taught that Cool is Better -- more refined," she writes. And then she devotes her book to making a convincing case for the bright appeal of hot orange, flame red, and gleaming yellow flowers in the garden. One flashy plant she singles out is crocosmia, a graceful and prolific option for gardeners who want a little sizzle in their landscape palette during mid to late summer when other plants brown out and the sunlight makes bright flowers glow.
Crocosmia has funnel-shaped or starry, 1-1/2 to 2 inch red, salmon, maroon, orange, and yellow flowers and long blade-shaped leaves that grow in fans much like gladiolus foliage. The flowers grow above the leaves, usually in two rows along simple or branching, arching spikes. The slender blossoms sometimes arch downward, rather like freesia flowers. A cousin of freesia and gladioli, it has similar growing requirements. The plants range in height from 2 to 4 feet tall, depending on variety and growing conditions, and they generally sprawl politely, but not always.
Most crocosmias are hardy in USDA Zones 6 through 10, but if you live in the colder regions of the range, you should mulch them with pine boughs over the winter. Crocosmia doesn't overwinter outdoors in cold-winter zones (colder than zone 5), where you have to dig the corms in the fall and replant them in spring (for details, see below).
Crocosmia has many selling points: The flamboyant colors add vivid visual interest to the garden for three to four weeks in mid to late summer (some varieties flower into fall); they make lovely, lasting cut flowers and border or container plants; they are rarely troubled by pests or diseases; and the plant is often listed among flora that deer don't find particularly appetizing. Just imagine -- a long border of brilliantly colored, stately plants that are low on the deer menu in your garden next year.
Crocosmia takes its name from the Greek krokos, for saffron and osme for smell, due to a saffronlike fragrance allegedly emitted when the dried flowers are immersed in water (though why anyone would soak dried flowers is mystifying). It's also known as montbretia, coppertip, and falling stars. Crocosmia shares the common name montbretia with a similar Iridaceae family member, Tritonia, and confusion surrounding the botanical names for the plants has been rectified in recent years, though montbretia is still used informally for Tritonia and Crocosmia in catalogs. To add to the muddle, synonymous names also used for some crocosmias include Antholyza and Curtonus.
Where to buy. You can order crocosmia from catalogs that specialize in spring-planted, summer-blooming bulbs. You can find them in mail-order sources in the $10 to $13 range for 25 to 30 corms. Garden centers also carry crocosmia. In stores, look for healthy, mildew-free corms (the bulblike part from which the plants grow), and plan to buy more than one if you want a rich patch of brilliant color.
Species and varieties. Crocosmia aurea has pale to burnt-orange, 1-1/2 to 2 inch flowers that appear semi-opposite on simple or branching spikes. Hardy to zone 7, this variety blooms in early summer. 'Flore Pleno' has double blossoms; 'Imperialis' offers robust, large brilliant-orange flowers, and 'Maculata' flowers have an orange-brown basal spot. C. aurea can be difficult to find.
Crocosmia masoniorum has reddish orange, 1-1/2 inch flowers that grow on one side of 2-1/2 to 3 foot arching spikes. The flowers are narrow at the base and widen to outspread lobes. C. masoniorum blooms in late summer. Hardy to zone 6, it must be dug up in all regions with frost. Some growers in the West call this species a "thug." In the well-drained soils of the West Coast, it can become weedy and crowd out more timid plants. In other areas, it's easily contained.
C. paniculata has alternating flowers of deep orange on erect, branching spikes. It flowers in summer, and grows to about 3 feet tall. This variety is not readily available, though it may be sold as Curtonus paniculatus.
C. pottsii, a smaller variety (to 24 inches), has flowers that grow horizontal to erect along one side of each branch of a branched spike. Its flowers are orange flushing to red, and the variety is hardy to zone 6.
Varieties. 'Lucifer', a 4-foot plant with flaming red-orange flowers, is the most common cultivated variety in the United States and hardy to zone 5. Other popular varieties include 'Bressingham Blaze', 'Bressingham Beacon' (both orange-red, to 2-1/2 feet tall), 'Citronella' (yellow with red-brown markings in the center), 'Emily McKenzie' (dark orange with red highlights, to 3 feet tall), 'Emberglow' (orange-brown, upward-arching flowers, to 2 feet tall), 'Firebird' (orange-red with green-tinted throats and 2-1/2 feet tall), 'Jenny Bloom' (yellow flowers, to 2-1/2 feet tall), and 'Solfaterre' (apricot-yellow flowers, to 2 feet tall).
In spring after the threat of frost has passed, plant the corms in clumps of 4 to 6 (except in regions where crocosmia becomes weedy), if you want an abundant display quickly. (Remember: You'll have to divide them in a few years to promote abundant bloom.) Set corms at a depth of 3 to 5 inches and space them 6 to 8 inches apart.
Growers in coastal and inland areas of southern California can plant as early as January through February. If you live in the Pacific Northwest, wait until April. The plants prefer full sun and moist, well-drained soil with average fertility and pH of about 6.5. Crocosmia tolerates partial shade, especially in the South and other hot areas. The plants are injured at temperatures below 28°F and need winter protection where temperatures fall below 10°F.
Most crocosmia varieties won't return where winter minimum temperatures fall below 20°F (zones 5a and colder). If you want to grow them in such areas, you have to dig up the corms after the first frost and store them in peat moss over the winter at about 50°F, as you would gladioli. However, the blaze of color that crocosmia sets in a garden may make that extra work worthwhile to you. Dusting lifted bulbs with sulfur helps to deter rot during storage. Don't let the stored corms dry out completely.
Lift and divide corms every three years or so to maintain vigorous blooming and to increase your supply of plants. Removing offsets found at the base of the main corm in the spring before growth begins is another method to produce more plants.
Pests. Spider mites can mar foliage, but they don't kill the plants. Generally, these plants are trouble-free. Some growers report that because crocosmia is related to gladioli, they may also be susceptible to gladiolus thrips.
Companion plants. The intense colors of crocosmia contrast well with hypericum, sundrops, baby's breath, coreopsis, Madonna lilies, rudbeckia, or white Shasta daisies. You could try unusual purple and reddish orange combinations of crocosmia with hydrangea, iris, or lavender.
Try planting it among orange and yellow azalea (Rhododendron species, hardy to zone 4), yellow and red weigela (W. florida, and other kinds hardy to zone 5), and other medium-sized shrubs in complementary colors. Deutzia (D. carnea 'Stellata') blooms earlier than crocosmia, extending successive flowerings of carmine blossoms in the garden from early spring into late summer.
Eileen Murray is a former editor of National Gardening magazine.
Photography by Suzanne DeJohn/National Gardening Association