The cultivation of saffron

Preparation

The soil selection

The Crocus sativus can be grown in many different soil types, provided it is well drained and not too wet. It is important to plant in "fresh" soil, preferably where flower bulb crops have never been grown before and certainly not from the same family as the crocus sativus, the Iridaceae. This is to prevent your bulbs from becoming ill due to residual germs, fungi, bacteria or nematodes.

To make a choice in which soil you will plant the bulbs, in addition to the moisture-retaining properties, you must also take into account the structure and workability of the soil. For example, on clay soil and soil with a lot of gravel and pebbles it will be much more difficult to get the bulbs properly in the ground than when you plant them in an easily workable sandy soil. The workability is also important if you want to dig up the bulbs from the ground after a few years to transplant them into fresh soil.

It is advisable to fertilize your land at least 10 weeks before planting with some old animal manure or good green compost. It is also important that you keep the land free of weeds as much as possible until the time of planting by mowing it regularly or working the soil shallowly with a garden cultivator or tiller from time to time. Just before planting, the soil can be plowed to make the soil loose and ready for planting.

The choice of wich saffron bulbs to plant

We offer both organic and conventionally grown Crocus sativus bulbs. Organic bulbs are cultivated without chemical plant protection products or fertilizers and are certified organic by Skal Biocontrol, ensuring that the harvested saffron can officially be labeled organic. Conventional bulbs, while not organic, are grown sustainably with minimal use of chemicals.

The size of the bulbs significantly impacts their flowering performance in the first year of planting. Larger bulbs yield better and more flowers initially, while smaller bulbs are better suited for long-term, cost-efficient cultivation.

Bulbs of size 7/8 are the most economical choice but rarely flower in the first year, making them ideal for establishing a multi-year crop. Size 8/9 bulbs have a first-year bloom rate of 40 to 80 percent, translating to 40–80 flowers per 100 bulbs.

For a strong saffron harvest in the first year, bulbs of size 9/10 or larger are recommended. Size 9/10 produces 1–2 flowers per bulb, size 10/11 yields 2–3 flowers, and size 11/+ delivers 3 or more flowers per bulb. Over time, bulb multiplication and growth enhance flowering rates under normal growing conditions.

The plantation of the saffron bulbs

The ideal planting period for Crocus sativus bulbs is between July and October. Summer heat promotes autumn flowering. For regions with temperate or cool summers, it’s best to delay planting until late August or early September, storing bulbs in a dry, ventilated place at 20–27°C until then. In regions where summer temperatures exceed 30°C, planting can begin as early as late July, but waiting until mid-August is recommended as the bulbs won’t germinate until late September.

Crocus sativus bulbs can be planted in various ways depending on soil moisture permeability. If puddles linger after rain, the soil has poor permeability, requiring raised planting beds. Conversely, well-draining soil allows for traditional planting beds. Typically, saffron bulbs are planted in rows with a density of 50 bulbs per square meter.

To plant, dig a trench about 15 cm deep along a line. Place the bulbs upright, plume facing up, maintaining a spacing of 8–10 cm between bulbs and 15 cm between rows. After planting the first row, shift the line 15 cm to the side and dig the next trench, covering the first with soil from the second. Repeat this process for up to four rows.

After planting every four rows, leave a path of 25–30 cm for walking, making it easier to weed and harvest saffron. For poorly draining soil, paths should be dug 15–20 cm deep to create raised beds for better water drainage. In such cases, keep a path after every two rows to improve water management and prevent bulb rot.

The growth cycle of the Crocus sativus

1. The bulb is in its dormant phase

2. Sprout and root formation

3. Flowering and leaf production

4. Flowering and leaf development

5. Further development of the leaves

6. Growth of the leaves and production of new bulbs

7. Growth of the leaves and production of new bulbs

8. Reaching maximum leaf length and continued growth of the new bulbs

9. Initiate leaf wilting and further growth of new bulbs

10. The leaves are completely wilted. The new bulbs have reached their maximum growth and return to dormancy.

The care and maintenance of the saffron cultivation

Because the Crocus sativus bulbs that you buy from us are dormant and this rest period lasts approximately from the end of June to the end of September, the bulbs do not need water in the summer. As soon as the bulbs start to form roots and sprouts, you can start watering if no rain is forecast and the soil is dry. During the flowering period you could irrigate after harvesting the saffron if necessary. In the spring, water is crucial for the Crocus sativus because then the new “daughter bulbs”, which have formed on top of the "mother bulb", must grow large enough to be able to form flowers in the fall. During periods of drought from March to June, watering about 30 mm per week is highly recommended. It is best to give this amount in two times 15 mm of water, spread over two days.

Despite the fact that the leaves of the Crocus sativus are green in winter, they can tolerate winter temperatures down to -15 degrees Celsius. However, it is wise to cover the crop with fleece or some straw if a period of frost with such low temperatures lasts for a long time or if there is a strong drying wind which can dry out the crop to such an extent that it dies. It is not a problem at all if the crop is covered with a layer of snow during a period of frost. Snow is the best covering material you can wish for during a severe winter, it ensures that the bulbs in the ground do not freeze and it keeps the leaves moist enough so that they do not suffer from the freezing cold.

Make sure that your saffron plantation remains as free of weeds as possible throughout the year. Weeds can overgrow the crocus crop, causing the Crocus sativus bulbs to grow less than normal, which can result in less flowering. When the Crocus sativus is above the ground with its green grassy leaves, it is best to remove the weeds by hand. It is especially necessary to ensure that the so-called root-propagated weeds do not get a chance to multiply in the planting bed. Root-propagated weeds are difficult to control because they have a hard-to-remove root system that continues to expand into the soil as the plant grows. Common root-propagated weeds are for example: couch grass (Elymus repens), yellow fieldcress (Rorippa sylvestris) and ground elder (Aegopodium podagraria). In the summer period, when the bulbs are in 'rest' and have no leaves, you can keep the soil free of weeds by hoeing. Another technique that is also used is to burn off the weeds with a special gas burner.

If you feel that the crop needs some nutrition during growth, it is best to fertilize in early spring with, for example, some dried cow manure pellets or compound N-P-K fertilizer. Spread the fertilization over 2 or 3 smaller doses over a number of weeks, preferably when the weather is favorable for growth and before rainfall or sprinkling. The amount of fertilizer required strongly depends on the amount of absorbable nutrients in the soil. Keep in mind that if the soil temperature rises, more nutrients are released for the crop that are already present in the soil. Temperature influences the solubility reactions of various nutrients and releases a larger amount of nutrients into the soil at higher temperatures. It is therefore important not to fertilize too much, especially when the soil temperature is still quite low.

Damage caused by wildlife during the cultivation of saffron

During the cultivation of saffron, you may need to protect the bulbs and the crop against wild animals.
For animals such as roe deer and hares, the green leaves of the Crocus sativus are a very welcome treat, especially in the winter months. If these animals are near your plantation, they will graze the leaves to the bottom if given the chance. To prevent this, you could fence the plantation with fencing net.

Rodents such as voles and mice, on the other hand, love the bulbs that are underground. These animals are capable of causing a lot of damage to your plantation without you immediately realizing it. Once you notice plants turning brown and dying, it's usually too late and they've already eaten a large portion of your bulbs.

To prevent this, we give you below a number of measures that you can take that keep these animals at a reasonable distance, but certainly do not offer a 100% guarantee.

How to protect your saffron cultivation from wildlife

You can cover your saffron field with some fine-meshed chicken wire after planting so that harmful rodents don't get a chance to get into the soil to eat your bulbs. Even though the diameter of the mesh is often a bit larger than a mouse hole, the animals don't like it and will think twice before digging.

You could use the technique of companion planting by surrounding your saffron plantation with a "smelly" crop like garlic. Voles and mice dislike strong-smelling crops. An ornamental flower bulb crop such as Fritillaria Imperialis (Emperor's Crown) also has a repellent effect against these animals with its strong scent.

Mice and voles do not like vibrations in the ground and will leave if they detect them. You could create vibrations in the ground by placing thin metal pins in the ground spread over the field, over which you place PET bottles upside down or mount some kind of windmill. As soon as the wind blows, it will transfer vibrations to the ground and scare away the rodents.

Pest animals can also be chased away with ultrasonic sound. For example, there are devices available in the specialist trade that operate on electricity or batteries and produce sounds that are inaudible to humans, but audible to animals. The very high frequency and strong intensity ensure that rodents no longer feel comfortable and will leave.

Voles and mice can, of course, also be caught by using conventional or live mousetraps. In the specialist trade you can find a wide range of products to catch these rodents. We strongly advise against combating rodents with poison. The reason for this is that you often not only poison mice or rats, but also very useful predators such as falcons, buzzards and owls that catch and eat these rodents.

The grubbing and transplanting of saffron bulbs

In commercial saffron farming, Crocus sativus bulbs are left in the ground for at least five consecutive years before being dug up and transplanted into fresh soil. This practice is essential because flowering and saffron yield decline over time. As the bulbs multiply annually, they eventually lack the space to grow large enough for optimal flowering. Saffron yields peak in the third year after planting, remain stable for a few years, and then start to decrease.

Summer heat is crucial for promoting autumn flowering. In regions with hot summers—where commercial saffron cultivation is common—bulbs receive sufficient heat in the soil and can remain undisturbed for several years. However, in areas with temperate or cool summers, it is advisable to lift the bulbs after two years to maintain their health and productivity.

Bulbs should be lifted from the ground in June, once their leaves have completely withered and turned brown, marking the start of their dormant phase, which lasts about three months. After lifting, the bulbs should be dried, cleaned, and sorted by size. Store them in a dry, sheltered, and well-ventilated location at a temperature of 20–27°C until planting, ensuring they receive sufficient summer heat.

When replanting, avoid using the same plot where saffron was previously grown. For reasons not fully understood, Crocus sativus bulbs perform poorly and are more prone to disease if planted back on the same land. Interestingly, if left undisturbed in fresh soil for several years, the bulbs remain healthy and productive. Always transplant bulbs into fresh soil for optimal growth and yield.

Between mid and late October, the largest Crocus sativus bulbs will begin to flower. Depending on the weather conditions, the period in which new flowers emerge from the ground lasts about three weeks. The saffron harvest can begin during this period, with the entire flower usually picked when it has just opened. It is often said that the flowers are best picked early in the morning before the flowers open, but we think that is a bit nonsense. Besides the fact that it is difficult to pick unopened flowers properly and undamaged, the pistils in the flower will be slightly longer when the flower is open, so that they are easier to remove later.

After the opened flowers have been picked, they are often spread out on a table, after which the pistils can be manually removed from the flower. Each flower has three stigmas that are attached to each other with their white ends. Because the best saffron consists only of the red part of the pistils, also called the stigmas, it is best to throw away the part where the pistil changes from red to light yellow and white. In the end, you will only have the beautiful red parts that you then collect in a container or on a dish.

When enough stigmas have been collected, we can start drying. Make sure that the stigmas that are harvested are dried on the same day to avoid loss of quality. Saffron flowers that have not yet been stripped can be kept refrigerated for several days, although this is not preferred. Drying saffron stigmas can be done in different ways. The most traditional way is to roast the stigmas over hot coals or a wood fire. You can do this by spreading them out on a very fine mesh grid and roasting them over the heat source until the saffron threads are sufficiently dry. Fortunately, nowadays there are more modern ways of drying herbs that are easier to control. For example, you can spread the fresh threads on an oven grid lined with baking paper and let them dry in the middle of a (convection) oven. At a temperature of about 50 to 60 degrees Celsius, drying takes between 15 and 30 minutes, depending on the type of oven and the amount you are drying at a time. The saffron is dry when it feels slightly crispy and no longer sticks together. The threads then have a vibrant dark red color with dark orange edged ends. There are also special spice dryers on the market that are very suitable for drying saffron threads.

After the saffron threads have dried, they should be packed airtight, for example in a glass jar or a tightly closed tin. Store the saffron in a cool, dry and dark place and it will be ready to use after about a month. Saffron can be kept for one and a half to two years without loss of quality