Crocus is a genus comprising about 90 species of perennial, early spring blooming corms. The flowers bloom in early spring, typically closing at night or on cloudy days and opening up with the morning sun, with many popular hybrids available. The plant foliage, basal, grass-like leaves with a central white stripe, turns yellow as plants go dormant several weeks after bloom. The plant is often used in rock gardens, beds, ground covers, lawns, and woodland gardens. It tolerates drought, but you should keep it moist during the growing season.
Crocus prefers full sun to partial shade and gritty, well-drained soil, sandy loam with composted organic matter. It will not grow in full shade. Avoid heavy clay. To plant from corms, plant in the fall about 2.5 inches deep and 2 inches apart, 35 to 70 corms per square foot. Plan to divide the corms about every 4 years. Note that plants are injured at temperatures below 14 degrees F (-10 degrees C).
Yellow-flowered crocuses and smaller-sized crocuses belong to other species, but all have ephemeral flowers which last about a day before drying and withering. Crocus flower colors vary enormously, although lilac, mauve, yellow, and white are the most common. Keep the foliage intact for about 6 weeks after blooms, as the leaves generate food for next year’s floral production.
Saffron is a species of crocus that is grown for its prized stamens. This expensive and labor-intensive spice is used to dye fabric but mostly to flavor foods. It is unknown in the wild and is a product of 3500 years of selective breeding by several different civilizations. This short plant has purple to lavender flowers that appear in fall for a 1-2 week period when the saffron spice can be collected. Each corm produces several flowers. The leaves are narrow and grass-like and appear shortly before flowering.
The corms should be planted 4 inches apart and 4 inches deep in well-drained soil with moderate levels of organic matter in full sun. The corms will multiply each year and can be divided to produce more plants. Plant in borders, walkways, rock gardens, or in mass plantings. To harvest the saffron remove the bright red stigmas and use fresh or dry and store in airtight containers for later use. American saffron actually refers to safflower, Carthamus tinctorius, whose flower heads yield a dye used as an adulterant to true saffron.
Source: Alexis Sheffield, Boyle County Horticulture Agent