1003 Crocus spp.Common Names: crocus, Dutch crocus, spring crocus Family: Liliaceae (lily Family)
There are some 80 species and hundreds of hybrids and cultivars in the genus Crocus, all of which are small, clump forming perennials that grow from corms (bulblike underground swollen stems). A crocus flower is shaped like a wine glass, with six tepals forming a goblet atop a long perianth tube that originates beneath the soil surface. Crocus flowers come in a wide range of intense colors, many with stripes or different colors inside and outside the tepals. Some crocus flowers are quite fragrant. A corm may produce one to five flowers, depending on the variety. Crocuses are small: The tepals may be 1 - 2 in (2.5 5 cm) long and the tube up to 6 in (15 cm) long. The leaves are grasslike. Crocuses are classified as either spring blooming, with flowers produced before the leaves in early spring; or fall blooming, with flowers produced in fall, usually on plants in full leaf. However, among the hundreds of crocuses in cultivation, there is really a continuum of flowering such that some cultivar or another may be blooming anytime from late summer through late spring. The table lists popular cultivated crocuses and their adaptability, flower color and height. Autumn crocus (Colchicum autumnale) is not a crocus at all, but a member of the lily family.
Crocuses grow wild in North Africa, the Middle East, Europe and temperate Asia. They have been cultivated for centuries, and saffron crocus was used as a food coloring and flavoring at least as early as 1500 BC.
CultureCrocuses form new corms above the old ones each year, and eventually this forces the plant up out of the soil. Therefore, they should be dug up, dried, and replanted every 3-4 years. Do this when the plants are dormant. Mice and other rodents enjoy a good crocus snack whenever they get a chance. Light: Grow crocuses in full sun to partial shade. Moisture: Many (but not all) crocuses come from the Mediterranean region, and are adapted to cool, wet winters and dry summers. These species, which are dormant in summer, may not do well outside in temperate climates with abundant rainfall in summer. They usually do better in containers where they can be kept dry in summer. The accompanying table lists crocuses that are easiest to grow in wet-summer climates, those that require dry summers, and those that can survive in southern gardens. Hardiness: USDA Zones 3 - 8. Hardiness varies with species and cultivars (see the table). Most Crocuses are quite frost hardy and most do well in cool climates. In warm areas, some crocuses may bloom the first year and never again. Propagation: Cormlets can be divided off the main corm during dormancy. Crocus seeds should be harvested as soon as the seed capsule ripens and before it splits open. Plant the seeds immediately and leave them in containers for two years before planting out. Grown from seed, crocuses will not bloom until their third year. Some crocuses will self seed. Plant the corms of spring blooming crocuses in autumn, 3-4 in (7-10 cm) deep. Plant fall blooming crocuses in late summer.
Many kinds of crocus will naturalize in a short grass lawn. Among these are C. vernus (Dutch crocus and the Dutch hybrids), and C. speciosus. Other, less vigorous varieties, should be planted in drifts in a herbaceous bed or border, or in a rock garden. Crocuses are especially appealing in pots, and can be brought indoors when blooming. The dried stigmas of Crocus sativus, the saffron crocus, are used in cooking for color and flavoring. Saffron crocus is a sterile cultivar whose exact origin is no longer known.
The following tables survey some of the most popular crocuses and use this key:
M = Adapted to Mediterranean climate (requires dry summers).
T = Easiest to grow in temperate climate, even with abundant summer rainfall.
S = Best choices for southern gardens.
The most common spring blooming crocuses in cultivation are:
|C. aerius||3-8 M||purple; yellow||1 - 3||3in (8cm)|
|C. ancyrencis; golden bunch||5-8||yellow; orange||5+||2in (5cm)|
|C. angustifolius; cloth-of-gold||3-8||yellow; orange||1 or 2||2in (5cm)|
|C. balansae||7-8||yellow; bronze; maroon||1 - 4||2in (5cm)|
|C. biflorus; Scotch crocus||3-8 M||lilac; blue; white; striped||1 or 2||2.5in (6cm)|
|C. cambessedesii||7-8 M||white; mauve||1 or 2||5in (13cm)|
|C. candidus||7-8 M||yellow||1 - 3||3in (8 cm)|
|C. chrysanthus; snow crocuses||3-8||cream; yellow; violet||1 - 4||2in (5cm)|
|C. corsicus||6-9||lilac; purple||1 or 2||3-4in (7-10cm)|
|C. cvijicii||3-8 T||golden yellow||1||4in (10cm)|
|C. dalmaticus||3-8 M||lilac||1||3in (8cm)|
|C. etruscus; 'Zwanenburg'||5-8||lilac-blue||1||3in (8cm)|
|C. flavus||4-8||orange-yellow||1-4||3in (7 cm)|
|C. fleischeri||6-8 M||pale yellow||1 or 2||2in (5cm)|
|C. imperati; 'De Jager'||5-8||violet-purple||1 or 2||4in (10cm)|
|C. korolkowii; Celandine||3-8||golden yellow||3-5||4in (10cm)|
|C. X luteus; Dutch yellow||3-8||pale to dark yellow||2 - 5||4in (10cm)|
|C. minimus||3-8 M||lilac-purple||1 or 2||3in (8cm)|
|C. olivieri||5-8 M||pale lemon-yellow||1 - 4||2in (5cm)|
|C. scardicus||6-8 T||lemon yellow||1||2in (5cm)|
|C. sieberi||3-8||pinkish lilac||1 - 3||3in (8cm)|
|C. tomasinianus||3-8 T; S||silvery lilac to purple||1 or 2||4in (10cm)|
|C. vernus; Dutch crocus||3-8 T||white; lilac; purple||1||5in (13cm)|
|C. versicolor||5-8||lemon yellow; ivory||1 or 2||4in (10cm)|
To see a similar table for the fall-blooming crocus, go to the Profile for autumn crocus Colchicum autumnale.
Steve Christman 1/4/06