Crocus is one of the first flowers to herald spring. Its small, vivid, cup-shaped flowers with bright yellow stamens appear in late winter and early spring. Lesser-known species of crocus bloom in autumn. Hardy in U.S. Department of Agriculture zones 3 to 9, crocuses grow from a bulblike corm. These perennials are usually 3 to 5 inches tall. The flowers bloom close to the ground on grasslike stems.
The earliest-blooming varieties of crocus include snow crocus (Crocus chrysanthus) and cloth-of-gold crocus (Crocus augustifolius). These flower in late winter, usually during the month of March. Scotch crocus (Crocs biflorus) and Dutch crocus (Crocus vernus) bloom slightly later, opening in early to mid-spring. These blossoms usually appear in late March or early April. Though the crocus is best known for its early spring blossoms, a few varieties bloom in fall. Examples include Autumn Blue, Autumn Gold, Autumn Lilac and Autumn White Crocus.
Crocus flowers can be yellow, white, purple, lavender or bicolour. For a visual punch, plant them in masses of the same colour. Group different varieties together to extend the bloom time from March to April. Crocuses are an excellent choice for naturalising into a lawn. Their stems resemble grass, and the blossoms bring a burst of spring colour to a lawn emerging from dormancy. They will die out after a few years in a dense lawn, however. Don't mow until their foliage turns yellow and dies.
Crocuses are part of a group of flowers gardeners refer to as bulbs. They are not true bulbs, however, but corms. Corms, fleshy underground food-storing structures, are similar to bulbs and are planted the same way. Plant them in early fall, placing the corms 3 to 4 inches into the soil with the buds facing up. Space them 2 to 3 inches apart. Each corm produces one to five blooms. Crocuses do best in full sun and sandy or gritty well-drained soil. They will not thrive in clay soil.
The crocus is a member of the Iris family Iridaceae. Its colourful blossoms first appear in late winter, even before daffodils and tulips. There are more than 80 species of crocus, with a few blooming in autumn. The crocus is native to central and southern Europe, North Africa, the Middle East and Central Asia. They are a common sight blooming in the foothills of the Alps in spring.