Saffron is collected from the blossoms of Crocus sativus (Iridaceae), commonly known as saffron crocus. It is propagated by bulbs called corms. Each corm forms new bulbs, and this is how the plant multiplies. Saffron flowers come out in autumn and are harvested for the red stigmas that we all know as saffron threads, from which the spice is derived. Each blossom yields three stigmas and are carefully picked by hand. The flowers must be harvested before noon time because they wither easily. This process is tedious and meticulous. This explains why saffron spice came to be so precious as to be called the red gold.
Saffron crocus is grown in countries like Iran, India, Afghanistan, Italy, France, New Zealand, Pennsylvania, Spain, Portugal, Greece and Morocco, Turkey and some parts of China. Since this plant is propagated in different parts of the world, planting techniques may differ too, depending on the climate, the type of soil, depth of planting and spacing of corms.
Crocus sativus corms adapt to the soil where they are planted deep. They grow well in arid or semi-arid lands. Corms adapt well in calcareous soil, which is neutral clay with pH 6 to 8. They also grow well in ferruginous, silty and sandy soil enriched with organic matter. In New Zealand, corms grow well in sandy or loamy soil. What is really important is that the soil is loose for roots to creep deep under, and well-drained to prevent corms from rotting or getting infected.
Saffron crocus grow in areas with temperatures ranging from no more than 35oC or 40oC in summer to about –15 oC or –20 oC in winter. Corms are also able to survive thru winter as cold as -10 oC because they have the capability to hibernate. When frost threatens to cover the fields, you can always cover the plants with straw for protection, until frost eases out. In Spain, Greece and other such areas, crocuses generally thrive in sunny areas especially in the course of the blooming phase, but irrigation is essential. In the case of India, rainfall is abundant and is considered good for growing corms, as it means higher yield of blossoms and cormlets (daughter corms). However, immense rain and very cold weather when the flowers are about to bloom, or have bloomed, will ruin the yield, so it is best to study the climate and plant the corms at the ideal time.
When planting saffron corms for the first time, choose a virgin patch of land, that is, no other tubers or saffron corms have ever been planted there before, if possible (if not, at least none in the past ten years). Before planting, it is advisable to till the soil 20 to 50 centimeters deep to keep the planting beds loose and well-aired, incorporating organic fertilizer during the process. The type of soil in Spain needs this pre-planting preparation, especially. Planting corms on raised beds are ideal for ensuring irrigation and drainage. Irrigation should be minimal once the corms started growing leaves. Planting is done in July, August and September either by hand or by machine, and harvesting comes at the end of October to mid-November, roughly eight weeks after planting. Saffron crocuses are sun-worshipping plants so they love to be planted in the dry open fields rather than in the shade.
Generally, corms are planted between 7-15 centimeters deep into the soil. The deeper they are planted, the lesser the corms multiply, the lesser the harvest but the higher the quality of the blossoms produced.
Observe the "row system" in planting corms. Each row is ideally 15 to 20 centimeters away from the other. Dig the holes in the first row and fill each with a corm. As you dig in the second row, use the soil that you dig up to cover the corms planted in the first row, and so on. Keep the rows raised for drainage and ventilation. Form a block of rows and leave enough space for a path to walk between each block such that it would be easy to navigate along the crocus field as you work to weed, water, and later on, harvest.
Spacing between corms are largely dependent on their sizes. In Italy, farmers plant corms spaced out at 2-3 centimeters and as deep as 10 to 15 centimeters, a technique that gives them a maximum harvest of blossoms and abundant cormlets. In Greece, farmers keep a 25-centimeter distance between each row and a 12-centimeter distance between corms, each of which is buried deep at 15 centimeters. In Spain, rows are far apart by 3 centimeters and the corms, by 6 centimeters. In India, there is a distance of 15 to 20 centimeters between each row, and between each corm, 7.5 to 10 centimeters.
Spacing also depends on how often grubbing is scheduled. Grubbing refers to the complete removal of saffron corms from the ground to separate the mother corms and the cormlets that have formed and to store them for the next planting season. Biennial grubbing requires a spacing of between 5-10 centimeters between each corm; for a longer period, make it between 10 to 20 centimeters.
Protective measures have to be taken against birds, rodents and rabbits. Corm rot, leaf rusts, nematodes and other pathogens must also be prevented from affecting the saffron crocus plants.
By the middle of October, saffron flowers begin to blossom, and this blooming lasts for about three weeks. There occurs a period of intensified blossoming called the "blanket days" which last from two to six days. Blooms that appear during the night must be harvested at dawn the very next day until before noon time to avoid wilting of the petals. It is best to harvest blooms that are still "sleeping" or closed to ensure high-quality saffron threads.
When the blooms are harvested, they are brought to the "stripping" area where the stigmas or threads are very carefully removed manually and painstakingly. The white and yellow parts of the stigma are not to be included in the cutting, just the red parts.
After the stripping comes immediately the drying, also known as toasting, which is done daily until the last threads are dried. Because they are exceedingly humid, the harvested stigmas are dehydrated by toasting at temperature not higher than 60 oC. Utmost care must be taken that the threads are not overdone. Hence, the "toaster" (the person assigned to do the task) has a very delicate role in the production of quality saffron spice. After the toasting, the threads will have reduced their size and weight extremely, down to 80% of the original. Five kilos of fresh stigmas yields a mere kilo of dried, vivid crimson threads.
Stigmas can also be dried over hot coals or in an oven. Spread the fresh threads on a wire mesh lined with baking paper and place in the middle of the oven. Turn the heat at 90 oC, observing the threads keenly for 10 to 20 minutes till they are dry enough to fall away from each other. For bulk drying, saffron threads are placed in a special room heated at 30 oC to 35 oC for 10-12 hours. A more modern method is the use of a dehydrator, with temperature set at 48 oC for 3 hours. The length of time, it seems, depends on the quantity of threads to dry. But the important thing is they are not overdried because that will reduce the quality and price of the saffron threads.
When the threads are dried, they turn into vivid dark red, with the tips being dark orange. They are cooled and wrapped in tissue or foil and placed inside airtight jars, covered and kept in a cool, dark corner for at least thirty days before they are ready for use. They can be kept in that nook for a year and still be good to use for flavoring dishes.
The corms of the saffron crocus stay good for cropping for four years, and on the fifth year, they need to be grubbed. In Spain and Italy, grubbing is done between June and July, and in Greece, it is done between May and June. Once the saffron leaves turn brown and wilted, the corms are dormant and are ready for grubbing.
The fields are upturned using a hoe or a plough machine and the corms are collected manually. The corms are then cleaned of weeds and unwanted bulbs, and new planting materials are classified according to sizes. The corms must not stay out in the sun longer than a couple of hours. Then these sorted corms are stored in a dark, dry but well-ventilated place until the next planting season.
Removing weeds requires the tedious, manual method, especially if you are dealing with root weeds. Machine-weeding may be used, but there is the danger of harming the bulbs. Thus, most farmers prefer to do it the traditional way. The longer the weeds stay in the saffron beds, the more difficult they will be to remove, so it is better to deal with them the soonest. When the saffron leaves have withered but it is not yet time for grubbing, remove the brown leaves to spot the weeds easily.
Saffron corms undergo stages of activity, transitory and dormancy. Activity period begins when they are planted and they grow roots, shoots, leaves and flowers. The transitory period happens when the corms become mother corms and produce new bulbs or cormlets. The dormancy period is when the corms reach the mature stage and are no longer producing new bulbs. The dormant period is characterized by wilted leaves and dried up roots. The corms would need to be dug up and allowed to rest for some time before they can be replanted to become productive again.
As to the planting area, it is very ideal to let a saffron field "rest" for at least ten to twelve years after a cropping cycle has been maximized in order to recover or be refreshed. It is best to move out to a virgin field or a refreshed field to start a new cycle. This will ensure you of a robust plantation that will give good yields for another term.
Corms are sorted according to their sizes. Apparently, the size of a corm will determine its yield. A study done in a university in Turkey resulted to a conclusion that the larger the mother corms, the more progenies it produces, the higher the yield for flowers and stigmas. It also showed that regeneration of corms reduce significantly over the years. The study also recommended for the smaller corms to be planted in virgin fields for them to grow in size.