Crocus sativus

Plant Characteristics

Habit		bulbous
Lifespan:	⌛	perennial

Cultivation

Features:	✓	flowers, edible
Minimum Temp:	☃	-10°C14 °F <br />263.15 K <br />473.67 °R <br />

Scientific Names

Iridaceae >

Crocus >

sativus >

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Saffron is a spice derived from the flower of the saffron crocus (Crocus sativus), a species of crocus in the Iridaceae family. A C. sativus flower bears three stigmas, each the distal end of a carpel. Together with their styles—stalks connecting stigmas to their host plant—stigmas are dried and used in cooking as a seasoning and colouring agent. Saffron, long the world's most expensive spice by weight, is native to Southwest Asia.

After aestivating in summer, the plant sends up five to eleven narrow and nearly vertical green leaves, each up to 40 cm in length. In autumn, purple buds appear. Only in October, after most other flowering plants have released their seeds, do its brilliantly hued flowers develop; they range from a light pastel shade of lilac to a darker and more striated mauve. Upon flowering, plants average less than 30 cm in height. A three-pronged style emerges from each flower. Each prong terminates with a vivid crimson stigma 25-30 mm in length.

Cultivation

C. sativus thrives in the Mediterranean maquis, the North American chaparral, and like climates where hot, dry summer breezes sweep semi-arid lands. It can nonetheless survive cold winters by tolerating frosts as low as -10C and short periods of snow cover. Irrigation is required if not grown in moist environments such as Kashmir, where annual rainfall averages 1000-1500 mm; saffron-growing regions in Greece 500 mm annually) and Spain (400 mm) are far drier. Timing is key: generous spring rains and drier summers are optimal. Rain immediately preceding flowering boosts saffron yields; rainy or cold weather during flowering spurs disease and low yields. Persistently damp and hot conditions harm crops, as do the digging actions of rabbits, rats, and birds. Nematodes, leaf rusts, and corm rot pose other threats.

The plants fare poorly in shady conditions; they grow best in strong sunlight. Planting is thus best done in fields that slope towards the sunlight (i.e., south-sloping in the Northern Hemisphere), maximizing sun exposure. Planting is mostly done in June in the Northern Hemisphere, where corms are lodged 7-15 cm deep. Planting depth and corm spacing, in concert with climate, are critical factors affecting yields. Mother corms planted deeper yield higher-quality saffron, though from fewer flower buds and daughter corms. Italian growers optimize thread yield by planting 15 cm deep and in rows 2–3 cm apart; depths of 8–10 cm optimizes flower and corm production. Greek, Moroccan, and Spanish growers have devised distinct depths and spacings to suit their locales.

C. sativus prefers friable, loose, low-density, well-watered, and well-drained clay-calcareous soils with high organic content. Traditional raised beds promote good drainage. Soil organic content was historically boosted via application of some 20–30 tonnes of manure per hectare. Afterwards—and with no further manure application—corms were planted. After a period of dormancy through the summer, the corms send up their narrow leaves and begin to bud in early autumn. Only in mid-autumn do they flower. Harvests are by necessity a speedy affair: after blossoming at dawn, flowers quickly wilt as the day passes. All plants bloom within a window of one or two weeks. Roughly 150 flowers yield 1 g of dry saffron threads; to produce 12 g of dried saffron (72 g freshly harvested), 1 kg of flowers are needed (1 lb for 0.2 oz of dried saffron). One fresh-picked flower yields an average 30 mg of fresh saffron or 7 mg of dried saffron.

Propagation

From offsets.

Gallery

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  C. sativus blossom

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  C. sativus blossom

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  Close-up of a single crocus thread (the dried stigma). Actual length is about 20 millimetres (0.79 in).

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  Saffron threads (red-coloured stigmas) mixed with styles (yellow) from Iran

References

• Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963

External links

• w:Crocus sativus. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
• Crocus sativus QR Code (Size 50, 100, 200, 500)