We are reprinting Pat Chadwick’s excellent article on fall-blooming bulbs from 2016.
If you plan it right, you can have a bulb of some sort in bloom throughout the entire growing season. We’re all familiar with daffodils, tulips, crocuses, hyacinths and a host of minor bulbs that typically brighten the late winter and spring landscapes. In summer, we are blessed with warm weather alliums, caladiums, elephant ears, gladiolus, Liatris, and lilies of various kinds. It may surprise you to learn that autumn has plenty to offer in the way of bulbs as well. Just as the rest of the garden is beginning to go dormant, the sight of many of the fall-blooming bulbs described below will intrigue and delight you.
COLCHICUM
Colchicum (pronounced KOHL-chi-kum) takes you by surprise when you encounter it in the autumn landscape. Closely related to lilies (Liliaceae family), it resembles a crocus on steroids.
However, it is not related to the crocus, which is a member of the Iris family and typically blooms in early spring. To add to the confusion, some crocuses bloom in the fall (more on those later), plus Colchicum is sometimes referred to as autumn crocus. It produces vase-shaped blooms beginning in September and continuing into November, depending on the species. Without going into all the botanical differences between the two species, here are a few ways to differentiate between a Colchicum and a crocus:
- Crocus foliage has a white line down the center of each leaf. Colchicum foliage does not.
- Crocus blossoms have three stamens. Colchicum blossoms have six.
- Crocus foliage occurs along with the blooms. Colchicum foliage, which is much larger, appears in spring and then dies back in summer. The flowers appear in autumn without foliage.
- Fall blooming crocus flowers are either white or bluish lavender. Colchicum flowers are generally pink or rose lavender, although white forms do exist.
- Crocus flowers are smaller than those of Colchicum.
It’s crucial to be aware that Colchicum is poisonous. Colchicine, the toxic compound in Colchicum, is extremely dangerous. Even tiny amounts can be lethal if ingested. A clear and prominent warning about handling this plant is crucial, especially in areas where children or pets are present. Wear garden gloves when handling the corms and check for sap on them. Always wash your hands thoroughly after handling, even if you wore gloves. Avoid touching your face or mouth during and after handling the plant or corms. Pruning or cutting back the plant can expose you to toxic sap, so take extra precautions during future garden maintenance. Also, avoid over-watering, which can cause toxin to leach into the nearby soil. Be sure to have emergency contact information available should you need to use it. It’s critical to understand that there is no antidote for colchicine poisoning. If exposure occurs, immediate medical attention is necessary, but outcomes depend largely on the amount of toxin absorbed.
In addition to the species, a number of Colchicum hybrids are available through catalogs and on-line sources, including the following selections:
- ‘Violet Queen’ has deep lilac blossoms with white veining.
- ‘Lilac Wonder’ has amethyst segments with white lines in the center and is very free flowering.
- ‘The Giant’ has mauve flowers that are white at the base. At 10 to 12 inches tall, it is one of the tallest of the Colchicum hybrids and is one of the most free flowering.
- ‘Waterlily’ is a double-flowered selection with pinkish-lavender blossoms that resemble those of its namesake in color and general form. This beautiful selection is one of the most popular of the Colchicum hybrids.
In addition to its toxicity, another downside to some Colchicum species is that their blossoms, which generally grow about 6 to 8 inches tall, tend to flop over after a few days. A solution to that problem is to plant the corms beneath a ground cover which will support the blossoms.
AUTUMN CROCUS
Crocuses are normally thought of as one of the earliest blooming of the spring bulbs. However, the genus includes a number of fall-blooming crocus species as well. With the exception of C. niveus, which has white flowers, the members of this fall-blooming group bloom in various shades of lavender. All of the autumn-blooming species are interesting, but the following two stand out as being of particular interest:
Crocus speciosus (Showy crocus) – This heirloom species, dating back to 1800, blooms in shades of mauve to violet blue. Just a few hybridized showy crocus selections include:
- ‘Cassiope’ – Large bluish lavender flowers
- ‘Aino’ – Large, deep bluish-purple flowers
- ‘Conqueror’ – Large, violet-blue flowers, which are significantly larger than other C. speciosus species.
Saffron Crocus (Crocus sativus) is the source of saffron, the culinary spice used to color and flavor many Indian, Asian, and Mediterranean dishes, including curries and Spanish paella. It takes about five dozen C. sativus blossoms to produce just one tablespoon of the reddish-orange threads, which are actually the stigmas from the blossoms. Each purple, cup-shaped blossom contains three stigmas. For the home gardener interested in growing C. sativus, plant two or three dozen bulbs in a sunny, well-drained location. They will gradually multiply, providing more of the spice with each successive year.
STERNBERGIA LUTEA
Commonly called lily of the field, this heirloom (pre-1601) bulb, a member of the Amaryllidaceae family, has identity issues. Its golden yellow blossoms look similar to those of a crocus. However, Sternbergia lutea is neither a lily nor a crocus. To add to the confusion, this bulb is sometimes referred to as autumn daffodil, yet it bears no resemblance whatsoever to daffodils other than its color. Despite the confusion about its identity, this four to six-inch tall plant provides plenty of color in the September landscape. It shows to best advantage at the front of the border either in small scattered groupings or in a large mass planting. The foliage appears along with the flowers and persists until spring before it finally dies back.
CYCLAMEN
A member of the Primulaceae family, low-growing Cyclamen is an excellent addition to rock gardens and naturalized shady woodland gardens.
The flowers range from white to deep magenta pink. While the uniquely shaped, reflexed flowers are dainty and lovely to look at, the beautifully mottled heart- or arrow-shaped foliage catches the eye in a natural setting. Depending on the species, the leaves may be marked with silver spots or zones or various shades of green or gray. The leaves and flower stalks arise directly from the Cyclamen tuber. Of the 20 species of Cyclamen that exist, choose the hardier forms for the autumn garden, such as C. hederifolium or C. purpurascens, which can thrive in USDA Zones 5 or 6. Do not confuse the hardy forms of Cyclamen with C. persicum, a large-flowered strain that was bred in the late 1800s for use as a house plant.
LYCORIS RADIATA
A member of the amaryllis family, this heirloom bulb is known by a series of common names (spider lily, magic lily, hurricane lily, surprise lily, naked ladies, resurrection lily, etc.). The bulbs typically lie dormant until late summer or early autumn rains trigger it to bloom. At that point, one to two-foot tall leafless flower stalks rise from the soil, each bearing umbels of four to six dramatic coral-red flowers. Each flower has very long spidery-looking stamens, which lends it an airy look and is the source of its common name of spider lily. The blooms fade quickly in hot weather but will last a bit longer when planted in partial shade. Once the flower stalk dies, the bulb sends up long, strap-like, grayish green leaves, which persist through winter and then die back in spring. Spider lilies naturalize by bulb offsets and will form small colonies over time. In addition to the red-blooming species, a variety called Alba has white blooms. A related species (L. aurea) produces golden yellow blossoms.
LYCORIS SQUAMIGERA
This cousin of L. radiata is the most cold hardy of the Lycoris species and shares many of the same common names as its red-flowering counterpart — naked lady, resurrection lily, or surprise Lily. Like L. radiata, this species is at its most glorious as a mass planting. The foliage appears in the spring and then dies back. In late summer, one to two-foot tall sturdy leafless scapes rise from the soil, each bearing 6 to 8 trumpet-shaped blossoms in a crown. The flower color on this species is a delicate shade of pinkish lavender. The blossoms are long lasting on the plant and as a cut flower in floral arrangements. The bulbs don’t like to be disturbed after they are planted and may not come up the first year. Divide the bulbs when flowering starts to become sparse and replant them immediately. They don’t like to dry out.
CANNA LILY
Canna lily is the exclusive member of the Cannaceae family and is another fall-blooming bulb (rhizome, actually) that swings into action in August and September when the rest of the garden is winding down. Nine species from the Americas and Asia belong to this family of plants. Most cannas grown today are hybrids that have been bred specifically for flower size and leaf coloration. For such hybrids, C. flaccida from Florida is the principal parent for flower size and C. indica from Central America is the major parent for variegated foliage. Height is an important consideration when selecting cannas for the landscape. While many selections top out at three to four feet, the tallest canna species or hybrids can grow to more than six feet. Fortunately, for gardeners who want a vertical accent but not one that tall, many shorter hybrids are available, including some dwarf varieties that grow only 18 to 24 inches tall. The shorter varieties make great accent plants for container gardens. Cannas bloom in a wide range of colors with interesting looking flower spikes that can last for several weeks. They attract pollinators of all kinds, including bees and other insects, hummingbirds, and even bats. Collectively, canna lilies make a dramatic statement in the mixed border with their bold foliage, colorful flowers, tropical appearance, and vertical form. While some canna selections are reported to be hardy in USDA Zone 7, others need protection from cold, wet winter conditions. If in doubt, carefully dig up the rhizomes to avoid damaging them and store them in a cool, frost-free area over winter. Replant in spring once the danger of frost is past.
DAHLIA
Members of the Asteraceae plant family, dahlias are perhaps the quintessential late-season flowering bulb. Originating in Mexico and Central America, this most glorious of fall-blooming bulbs was prized by the Aztecs centuries ago. Finding its way to Europe in the late 1700s, it became widely hybridized and eventually circled back to the New World, where it is enthusiastically grown by both collectors and gardening amateurs alike. For those of us who think the rose is the queen of the ornamental garden, it could be argued that the glorious, dramatic, scene-stealing dahlia presents some serious competition for the title. More than 20,000 dahlia cultivars are listed on the Royal Horticultural Society’s International Registry. The American Dahlia Society recognizes a number of dahlia forms, including collarette, waterlily, decorative, ball, pom pom, cactus, anemone, and single-flowered. Technically a tuber rather than a bulb, dahlias should be planted about two weeks before the last expected frost in a sunny location in soil that has been deeply cultivated and amended with organic matter. In autumn, carefully dig up the tubers after frost kills the foliage. Once the soil dries on the roots, clean them with a soft brush or cloth and store in a well-ventilated, frost-free area.
CULTURAL REQUIREMENTS AND CARE OF FALL-FLOWERING BULBS
Fall-flowering bulbs, corms, rhizomes and tubers are generally low maintenance and have few cultural requirements.
- Before planting, choose the site carefully. Some of these plants do not like to be disturbed once they are planted.
- Of the bulbs described, most prefer a sunny to partially shady site. Colchicum and autumn crocus will bloom only when the flowers are exposed to sunlight. Cyclamen, on the other hand, prefers some shade.
- Plant in moderately fertile, well-drained soil. Good drainage is particularly important in winter.
- Plant at the proper recommended depth for the species.
- Plant with the root side down. If it’s not possible to figure this out, plant the bulb on its side.
- Mark where autumn-blooming species are planted to avoid planting over top of them in spring.
- In the absence of rain, provide some water during periods of drought. Some fall-flowering bulbs require moisture in order to bloom.
- Most autumn-blooming bulbs are deer, rabbit, and vole resistant and subject to few, if any, plant diseases.
When to plant fall-blooming bulbs
Some experts recommend planting fall-flowering bulbs in August (University of Maryland Extension), while others recommend planting in early fall (University of Tennessee/Horticulture) or simply late summer or early fall (Iowa State Extension/Colchicum). “You can plant a bulb in summer for bloom that fall” (North Carolina State University Extension/ Colchicum).
SOURCES
American Dahlia Society (http://www.dahlia.org/)
Bulbs (Bryan, John E., 2002)
Clemson Cooperative Extension Pub. HGIC 1156, ‘Summer- & Fall-Flowering Bulbs, (www.clemson.edu)
“Dahlias,” Chicago Botanic Garden article (http://www.chicagobotanic.org/plantinfo/dahlias)
50 Beautiful Deer-Resistant Plants – The Prettiest Annuals, Perennials, Bulbs, and Shrubs that Deer Don’t Eat (Clausen, Ruth Rogers, 2011)
