The world’s most expensive spice, saffron, is produced by the saffron crocus, Crocus sativus. This intriguing and lovely flower’s story is intertwined with a human history that spans no less than 3000 years. In truth, it does not exist naturally anywhere, but rather is a sterile triploid cultivated through the centuries for its deep orange-red style and stigmata – the only part of the plant that is used to make the spice saffron. In addition, it is a welcome plant to any garden that meets its basic needs.
Crocus sativus bulbs are not true bulbs, but rather corms that closely mimic tunicate bulbs, complete with a dry outer sheath or tunic. In mid fall the leaves begin to sprout and grow just before the flowers emerge, or sometimes just after flowering. The blue-green leaves are long, thin and grass-like, growing up to 30 cm long, and have a lighter green vein down the middle. Each corm supports 5-10 of these. The leaves remain green throughout winter, dying back in spring. The above ground plant is fully dormant all summer.
The flowers open simultaneously. Each is around 6 cm across, and bears 5-6 broad lilac-purple petals with darker veins. The style is three pronged with each terminating in a stigma – the female part of the flower. The bright yellow anthers, also three in number, bear pollen, yet it is sterile, so no seeds can be produced. C. sativus is a autumn crocus, with flowering commencing in late October into late November depending on location and weather conditions.
The origins of C. sativus are not well known given its long history in cultivation. It is thought to be a selectively bred form of the naturally occurring C. cartwrightianus, a native of Greece and the Cyclades, an island group in the Aegean Sea. This species however has smaller flowers and the style/stigma lack the flavor of C. sativus. Unlike its triploid cousin, it is seed producing.
Today saffron crocus is grown across the world in any suitable climate. While it makes a lovely flowering bulb for the garden, it is mostly grown for the valuable spice, saffron. It has been grown for this purpose throughout much of Europe, the middle east, India, China, and even New Zealand and the USA. Today, Iran is the largest producer, yet Spain is the largest exporter. To this day no spice by weight is more expensive than saffron.
Like many natural herbal products, saffron contains a wealth of aromatic and volatile chemicals, giving its flavor and smell, as well as nonvolatile substances, such as carotenoids, that provide color and flavor. One of saffron’s most celebrated constituents is safranal, a volatile oil that furnishes most of its aroma. The spice is dried and must remain so to preserve this exotic cocktail of chemicals, therefore it must be kept in well sealed containers.
Throughout its history saffron has been used as in dyes, in perfumes, in medicines, in body washes, as a narcotic, in aphrodisiacs, as an antidepressant, in potpourris, in make up, and of course as a spice, both coloring and flavoring all manner of foods and spirits. While historical use of saffron for a wide range of ailments is well documented, more recently it has been studied for possible anticarcinogenic and antioxidant properties.
History and chemistry aside, C. sativus is a relatively easy plant to grow, but less easy to flower. It does best in Mediterranean type climates that have cool, moist winters and dry, hot summers. Spain, Greece, and Iran are near perfect for their cultivation, yet this plant can be grown in far flung regions the world over. It prefers places with ample spring and early fall rains, however too much rain during flowering can lead to them rotting prematurely.
This is a plant that needs lots of sun to grow and flower well. While full sun is best, I have managed to grow it (and even flower it some years) in a spot that only receives 4 or less hours of sunlight daily. It likes a rich soil, but it should be sharply draining, especially in the summer months when the plant is dormant. Many sources site deep planting as beneficial, up to 20 cm, yet my plants grow at half that depth without problems.
The bigger issue is getting them to flower. Toward that end, the aforementioned deep planting is suggested, as well as giving them plenty of water during growth, and a rich growing medium. While plants seem to grow and flourish for many years, they can be fickle about flowering. In the 6 years I’ve grown them, they have flowered handsomely twice, while some years they give not one bloom.
Soil pH should be around neutral to slightly acidic. Mine are in a rich volcanic loam that while heavy is surprisingly free draining. They have grown year after year without incident, even enduring the unrelenting monsoon rains of June and July. Very likely the intensely hot dry conditions of August and September have saved them from an early demise. While good drainage will protect the corms from rot, care should be given not to over water this plant.
Fertilizer can be applied while in growth if your soils are very poor, but I’d go easy on it. In saffron producing regions, manure is often used for this purpose. Occasionally I throw a pelleted organic fertilizer over my bulb beds. A bit of lime once a year wouldn’t hurt either if your soils are acidic.
Propagation is by division of the corms. This may also lead to better flowering is subsequent years, as with daffodils. Spring is the best time to divide clumps and plant newly acquired corms. This plant is commonly available from bulb companies and at retail nurseries.
While Crocus sativus comes from regions with pretty mellow winters, it has been grown successfully in the northern USA, England, and Switzerland. A south facing, well drained slope is recommended for colder climates. It is cold hardy from USDA zones 6a through 9b.
Here’s another versatile and lovely flowering bulb for your garden. If you can get them to flower well, you’ll have a bonus – home grown saffron!