International Flower Bulb Centre
Plant Common Name
Hybrid Crocus, Spring Crocus
Most gardeners know the delight of the first crocus of spring. Relatively few, though, have experienced the joy of crocuses at other seasons. Yet, in their native haunts in Europe and western Asia, these hardy herbaceous "bulbs" are as much a presence at the growing season's end as at its beginning.
Crocus are members of the Iris family, Iridaceae. They bear chalice-shaped flowers of yellow, blue, purple, or white with long floral tubes that extend underground and may bloom in winter, spring, or fall. The flowers have three inner and three outer petals/tepals that often differ in color. The outer petals are sometimes darker or striped on their exteriors, which helps camouflage the flowers when closed. The plants have grassy leaves, sometimes with a prominent white or silver mid-stripe. The foliage can appear at different times. The leaves of spring-bloomers appear when the plants flower, but those of fall-blooming crocuses appear in fall and can continue through winter. The leaves and flowers grow directly from a bulb-like storage organ known as a corm, which lacks fleshy scales (unlike bulbs) and renews itself annually.
Most crocuses offered in stores and catalogs are of two types. Hybrids and selections of Crocus chrysanthus (snow crocus) and C. biflorus (Scotch crocus), which produce relatively modest flowers in late winter and early spring. Some common cultivars include the large golden-yellow 'Gipsy Girl', rich blue 'Ladykiller', and gray-white 'Miss Vain'.
Numerous other spring-blooming species make wonderful garden plants, including C. tommasinianus and its cultivars such as 'Barr's Purple' and cyclamen-pink 'Roseus'; C. ancyrensis and C. korolkowii, which have glowing yellow flowers very early in the season; the highly variable C. sieberi, often represented in gardens by the remarkable purple, white, and gold-striped cultivar 'Tricolor.'
Receiving much less attention from gardeners, but equally valuable as ornamental plants, fall-blooming species include the large-flowered, hardy, and reliable C. speciosus, which has numerous excellent cultivars in shades of white ('Albus'), lilac ('Aitchisonii' and 'Artabir'), and violet ('Cassiope' and 'Oxonian'); its close cousin C. pulchellus which has daintier, more rounded flowers; C. goulimyi, whose shapely pale lilac-blue goblets of are the embodiment of elegance; C. cancellatus among the earliest and showiest late-season crocuses with purple-striped flowers in late summer; and C. niveus, a leading contender for the title of most beautiful white crocus.
Most crocuses prefer sun and well-drained soil, although some such as C. tommasinianus also thrive in partial shade. All crocuses prefer some winter chill, but spring-blooming species tend to require and tolerate more cold than do fall crocuses, which are mostly native to the Mediterranean region. Plant the corms in quantity in the open garden, or in lesser number in more intimate areas such as rock gardens, terraces, and dooryards. C. vernus hybrids, C. tommasinianus, and a few other species and cultivars will self-sow to form colonies in beds and lawns.
Crocus corms are favorites of squirrels, chipmunks, and other burrowing herbivores. Bury corms under hardware cloth if predation is a problem.