Extension News

Late Summer and Fall-Blooming Bulbs

Note to media editors: This is the Garden Column for the week of Aug. 10, 2007

8/6/2007

By Richard Jauron
Horticulturist
Iowa State University Extension

Spring-flowering bulbs, such as tulips and daffodils, are familiar to all gardeners. Though not widely planted, the attractive flowers and unique life cycles of the colchicum, showy crocus and magic lily make them welcome additions to the garden. 

Colchicums (Colchicum spp.) arise from bulb-like corms. The leaves of colchicums emerge in early spring and die back by early summer. White to pink to purple, crocus-like flowers appear without foliage in late summer or fall. They are also known as autumn crocuses. 

Colchicums should be planted immediately upon their purchase or receipt as the corms will bloom within a few weeks. (If not planted promptly, the corms may bloom during storage.) Plant the corms in well-drained soils in partial shade to full sun. Good planting sites include areas within the filtered shade of large trees and shrubs, in rock gardens, or amongst low-growing groundcovers such as vinca. For the best visual display, plant colchicums in clumps. The corms should be planted 2 to 3 inches deep and 6 inches apart. 

Gardeners can choose from several excellent cultivars (varieties). ‘Album’ produces pure white flowers.  ‘Alboplenum’ has double, white flowers. The flowers of ‘The Giant’ are 10 to 12 inches tall and violet with a white throat.  ‘Lilac Wonder’ bears large, rosy-purple flowers. ‘Waterlily’ produces double, lilac-pink flowers which resemble a water lily. 

Colchicums are native to Europe and northern Africa. The scientific name comes from Colchis, an ancient country bordering on the Black Sea, now part of the Georgian Republic, where colchicums are abundant. 

The dried corms and seeds of Colchicum autumnale are the source of medicinal colchicum.  It is also the source of colchicine which is used in plant breeding to induce polyploids. 

Another attractive fall-blooming bulb (actually a bulb-like corm) is showy crocus (Crocus speciosus). Flowers are violet-blue with yellow anthers and deep orange stigmas. Plant height is approximately 5 to 6 inches. Excellent cultivars include ‘Albus’ which produces white flowers, ‘Cassiope’ has aster-blue flowers with yellow bases, ‘Conqueror’ produces clear, deep blue flowers, and ‘Oxonian’ has large, dark blue flowers. Showy crocus blooms in late September or October. 

Showy crocus performs best in partial to full sun in a well-drained soil. Possible planting sites include rock gardens, naturalized areas, and perennial borders. Plant the corms 3 to 4 inches deep in groups of 25 or more. 

Another intriguing plant is Lycoris squamigera. Common names include magic lily, resurrection lily, surprise lily, and naked lady.  The life cycle of Lycoris squamigera is similar to colchicums.  The long, strap-shaped leaves emerge in spring, but die back to the ground by early summer. Pink, lily-like flowers are borne on 18- to 24-inch-tall, leafless, flower stalks in mid to late summer. Each flower stalk produces 4 to 12 flowers. 

Lycoris squamigera performs best in partial shade to full sun in well-drained soils. Plant bulbs 4 to 5 inches deep and 6 to 8 inches apart. Since the dying foliage is rather unsightly, interplant the magic lily with other perennials. 

The brightly colored flowers of tulips, daffodils, crocuses and other spring-flowering bulbs are a beautiful sight in the garden after a long, dreary winter. However, when selecting bulbs for the garden, don’t forget the attractive, intriguing, late summer and fall-blooming bulbs.

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Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu