Plant Encyclopedia

Crocus sativus, the saffron crocus


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 flowers

Saffron crocus is an autumn crocus, flowering in October and November.

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 grasslike, 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.

 

Saffron

Saffron is the dried style and stigmata of Crocus sativus. These are freshly collected.

 

 

 

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.

Crocus sativus corms

Crocus sativus bulbs are not true bulbs, but rather corms. Each lasts just one growing season, but can be replaced by many more.

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.

 

 

Crocus sativus flower

The flower of Crocus sativus is large and showy. The three pronged style and stigmata are an exceptional feature of this flower and the source of saffron spice.

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 overwater 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 pelletized organic fertilizer over my bulb beds. A bit of lime once a year wouldn’t hurt either if your soils are acidic.

 

Crocus sativus clumps

When in full flower Crocus sativus is a show stopper just before the frosts of late autumn set in. This is the best flowering I have got from my plants.

 

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!

 

8 Responses to “Crocus sativus, the saffron crocus”

  1. Pandya says:

    I live in California. My safron bulbs multiply every & grow as well but last year & this year there have been no flowers. The first year there were flowers in each & every bulb.
    Question
    1. Do you continue watering the bulbs in summer during dormant months? I did not but the bulbs still bloomed.
    2. I dug out the bulbs & replanted & started watering them in Jul-Aug this year. Is that too late to start watering? Is that why the bulbs did bloom but there are no flowers?

    Any tips will be really helpful.

    Thanks

    • tommy says:

      Pandya, I’m no expert on growing saffron, in fact I was rather surprised when they continued to multiply and flower for me. To answer your questions: 1) No, I wouldn’t water them at all while dormant. 2) Replanting shouldn’t be a problem when the plants are not in flower, but watering in summer is probably not a good idea. In their native home summers are HOT and dry. If you water them I’d start once you see some top growth (just before they flower), but not before. I’m guessing that the lack of flowers is more due to not meeting some other need – growing them too shady, for example. These thrive in full sun conditions.

      Other things to consider – the soil should be very well draining, have a pH from around 6-8, and it should be on the dry side in summer. If you’ve had severe drought conditions during summer one watering in September should tide them over nicely, but don’t water them again before flowering. In general the hotter the summer, the better they will flower in the fall.

      I hope that helps!

      Tom

  2. Steve says:

    Hi Tom,
    What kind of potting soil do you suggest for Saffron bulbs in pots-a cactus/succulent soil?
    Mine are 1st year bulbs in pots and indoors. I live in the San Joaquin Valley in Central California.
    Any suggestions are helpful.
    Thank you,
    Steven

    • tommy says:

      Steven,

      I’d add a fair bit of crumbly loam to any gritty mix for best growth. They should do well in containers if they are large sized and the bulbs are planted quite deep. Bulbs too near the surface will produce many smaller bulbs, but probably won’t flower well. If you can plant them in the ground, that probably would be even better. C. sativus will grow and flower in light shade, but do best in full sun. I’ve never tried to grow them indoors.

  3. Mary Lou Smith says:

    I have grown saffron for years and this spring is the first time I have dug them up to divide them. Believe me, I have done nothing more than just stick them in ordinary garden soil (which is a bit on the clayey side) on the southwest side of my house. Sun is afternoon sun in the summer and a bit more when the sun is lower in the winter. I live in Denver and they have done just fine. I think we imitate their native conditions quite well here – high desert.

    Just when you think that the garden is done for the year each fall, these pretty little croci come up and surprise you. It’s so much fun to say, “I grow my own saffron!”

    • tommy says:

      Thanks for your comments Mary Lou. Indeed, your conditions probably are much closer to those for this plant in its homeland – certainly closer than southern Japan, which is anything but high desert!

  4. Michael Awad says:

    Hi Tommy;
    Just need to know if we can grow these beautiful flowers in green houses, where we can control temp, humidity, timely watering and artificial lights, as there is little sun?
    Also in green house, what is best soil to use? Fertilization once a year, more or less? Do you know any growers who do it in green houses?
    Appreciate your help.
    Michael

    • tommy says:

      Hi Michael. I can’t say I’ve ever heard of this species being grown in a greenhouse, though it may have been done before. If you do grow it that way, realize it likes a lot of light, meaning full sun. It hails from the eastern Mediterranean region where winters are relatively short, moist and not too cold. Summers are the converse, long and hot. That is probably why it adapted to be a winter growing plant. The growing medium should be perfectly draining or you will have rot problems. In pots I would recommend an inorganic mix with little or no true soil component. Perlite, coarse sand, and the like are good candidate components. Don’t use peat or any other quickly composting organic. The pH should be right around neutral.

      So, given all that, be sure to use strong lighting that mimics winter sun around 30 degrees latitude. Fertilizer will be necessary if you use an inorganic mix, so I’d say every other watering, use a VERY dilute soluble fertilizer, but only when the plants are in growth. Flush the next watering with pure water. Also, it is said they do better if planted deep, so use deep pots and plant them at least 10 cm deep). Good luck and have fun!

      Tom

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