Every autumn, baron fields across Iran, Greece, Kashmir, Spain, and Morocco, are transformed into seas of violet, as the tiny Crocuses rear their heads from the loose, clayish soil. These demanding, delicate flowers yield the world’s most expensive spice – saffron. The precious spice gets its name from the Persian word “Zarparan”, meaning “creating gold”.
Through its long and illustrious history, saffron has always been traded at a premium price. What makes it so expensive, is not the fact that it is limited to certain geographical regions, or that it has to travel the globe, but rather because it is an extremely labour-intensive crop. The cultivation of saffron is an ancient practice – little has changed since the wild crocus was first domesticated by Persians in the 10th century BCE.
Saffron is not a high-maintenance crop in terms of cultivation, but the harvest requires a lot of painstaking handwork. the yield of saffron is also very low. The flowers have to be collected in the hundreds and thousands to produce a few grams of saffron. Saffron is also a very precise crop. The quality of saffron is determined by environmental conditions, as well as nutrition, soil condition, irrigation, and post-harvest processes.
In this blog post, we will dive deep into the processes involved in farming the world’s most expensive spice and the optimal requirements needed to harvest the best quality saffron. Let’s start with soil, as the quality is extremely important to the cultivation of saffron.
The optimal soil condition
So, the question is: in what type of soil does saffron crocus best grow? The saffron flower known as Crocus sativus, thrives in loose, low-density, and well-drained soil, rich in nutrients. For saffron corms to grow, the soil conditions must be met.
The ideal soil composition for saffron consists of 40% sand, 40% silt, and 20% clay, which is known as loam soil. This type of soil allows for optimal air circulation and it allows for good drainage. The pH levels should be between 7 and 9; ranging from neutral to slightly alkaline.
The crocus is mainly grown in temperate climate conditions where the corms need full-day sun. That is why saffron is harvested in open fields and shaded grounds, tree-full grounds, and rice grass fields are usually avoided.
Depending on region and setup, the cultivation methods can slightly differ. However, the first step is always to prepare the land. In late autumn or early winter, after seasonal rains have softened the soil, the saffron fields are ploughed. However, if there hasn’t been enough rainfall, this step can be pushed back until spring, ideally in May.
After spring rains, the field is ploughed again, this time 25 to 30 cm deep. The time for deep ploughing can differ depending on the region, but the soil should have reached a state where it’s not sticky and it easily breaks up. After completing this process, the land is left to fallow.
After 2 to 3 weeks, twice the field is ploughed perpendicular to the slope. This phase is very important as it creates balance within the texture of the soil. Otherwise, moisture remains only on the surface of the soil, with the deeper layers remaining parched. This step can hugely affect the growth of saffron corms. At this stage, fertilizers can be incorporated into the soil to increase yield of saffron and to improve the weight of secondary corms.
Now the land is ready to receive the precious saffron bulbs.
The cultivation process
Each saffron crop goes through a four-stage cycle which starts with the development of corms during late autumn and winter. At the start of spring, the second stage begins when the corms start reproducing. This is then followed by the dormancy period. The final stage is flowering which begins in autumn when the blossoms first appear. Cultivation starts with planting the corms.
Saffron is a perennial, sterile plant that is propagated by producing secondary corms. Each corm develops a minimum of three daughter corms which replace the parent. Over the years the number of secondary corms increases. The reproduction of bulbs, however, can lead to overcrowding which significantly impacts flowering and reduces saffron yield.
To avoid this, the bulbs are dug out between June and October, during the dormancy period. This is a key step in cultivating saffron, not only to prevent overcrowding but also to ensure the health of the corms. During the sorting process, the daughter corms are separated and the damaged, crushed, or mouldy bulbs are removed. The healthy corms are then divided into three groups based on their size.
Afterward, the saffron bulbs are treated by removing the extra fibrous layer and the button-shaped tissue at the bottom of the bulb, which is last year’s mother corm that died and transferred its nutrients to the daughter corm. The corms are then disinfected to get rid of any mites or fungi. Now the bulbs are ready to go into the soil.
Saffron corms are planted between August and September in long rows, at an ideal depth of 15-20 cm. This protects the corms against extreme temperatures and sunlight. There should be a 5-10 cm distance between each bulb. Depending on the region, the corms are kept in the same plot of land for an average of 4-5 years. After that the soil is restored and new corms are planted.
Optimal Irrigation
Unlike many crops, saffron is resistant to drought and does not require much water. However, the method and timing of irrigation directly affect the quality and quantity of saffron flowers. The initial phase of irrigation should happen right before the saffron leaves sprout. Too soon, the bulbs become weak and harvest becomes difficult. Too late, and flowering is delayed and the blossoms are threatened by cold temperatures.
To determine the time of irrigation, a few sample bulbs are removed from different parts of the field and examined in mid-October. If the sprouts are already 2 cm high, then we can fully irrigate the fields, otherwise, irrigation is pushed back to the last week of October. Depending on the region and local temperatures, the time of irrigation can be different.
After the first irrigation, the upper layer of the soil, at just 7 cm deep, is raked. This helps the soil maintain its moisture. It will also be easier to remove the weeds and allow the plant to easily sprout and grow. Two to three weeks after the initial irrigation the saffron flowers start to bloom. This is when the painstaking process of harvest begins.
The harvest
Saffron is an autumn-flowering crocus. Depending on the climate and the region, in early to late autumn, the grass-like leaves of the crocus rear their heads from the loose soil, bearing the exotic purple flowers. Each of the delicate blossoms has 6 violet petals with three visible red stigmas that become the saffron threads. Each saffron bulb produces one to five flowers over 3 to 4 days, and harvest will go on for nearly a month.
Harvesting these tiny flowers is the most important and intensive part of the process. Performed manually, the crocuses need to be handpicked with care and patience. It’s a tedious and backbreaking task – to pick the flowers, the harvesters need to walk up and down the rows for extended days, gently picking the flowers.
Time is the other challenging aspect of harvest. The flowers are picked in the early hours of the morning, within just a few hours after blooming, while they are still fresh. Exposure to light and humidity will damage the stigmas and compromise the quality of saffron. It takes about an hour to pick 1,000 flowers, and to produce one kilo of saffron, around 150,000 flowers are needed.
This puts a lot of strain on labourers as they have to work swiftly and efficiently; while making sure the flowers don’t get damaged. No pressure should be applied to flowers during transfer and storage. Before starting the separation process, the flowers should be kept in a dry, cool, and clean room with no direct sunlight. At this point, the flowers are ready for the final stage.
Optimal drying conditions
The post-harvest process begins with removing the stigmas from the flowers. The flowers are opened and the delicate threads are carefully pulled out. The stigmas are then trimmed and processed based on the type of saffron and market requirements. The Persian saffron for example is classified into four categories in terms of quality:
- Sargol is the very tip of the saffron thread with a deep red colour. Even though it is very high in quality, the trim is very short and the threads are prone to breakage.
- Super Negin is the most expensive trim with the strongest colour and aroma. The threads are a long crimson red.
- Negin has a longer trim which contains some orange and yellow parts of the stigmas as well. Although it is lower in quality, it still offers a pleasant taste and aroma.
- Pushal is the cheapest trim and it only contains the orange and yellow parts of the stigma and has no actual value.
Apart from the trim, the quality of saffron is determined by the concentration of its primary compounds: crocin which gives saffron its distinctive golden colour, picrocrocin which is responsible for its bitter, hay-like taste, and safranal which gives saffron its enchanting aroma. The drying process plays an important part in enhancing and preserving the quality of these compounds.
During the dehydrating process, the stigmas lose 80% of their moisture. This process should happen immediately after harvest and it is vital as it prevents the build-up of moulds and extends the spice’s shelf-life. The drying technique, temperature, and duration varies in different regions.
In drier climates, the threads are left in the open air to dry naturally. In humid or colder climates, the threads are dried artificially using machinery to speed up the dehydration process. Temperature is also important in determining the quality of saffron. According to research, high temperatures generate more safranal and crocin compared to milder temperatures. As a result, the saffron will have a more potent colour and aroma.
Once dried, the saffron threads should be stored in an airtight container and kept in a cool and dry place, away from sunlight. It’s best to avoid using saffron immediately after drying as the flavour and aroma develop and become stronger over time.