Saffron – a delicate, exotic and expensive spice from far away lands? Not necessarily so. Saffron spice consists of the dark red-gold, dried stigma of the saffron corm flower and has traditionally been grown outdoors on a commercial scale in countries such as Spain, India and Iran where the climate is warm and dry and labor cheap for the time consuming process of harvesting. However, saffron is not difficult to grow indoors and these days saffron bulbs are readily obtainable at the right time of year for those who want to grow some of their own exotic spice. While saffron bulbs may take up little space, their yield is somewhat low – it takes around two pounds of fresh flowers to give 2.5 ounces of red stigmas, which when dried results in a yield of 0.4 ounces of usable spice. Each saffron corm usually produces between one and three flowers in a season so yields per square foot are perhaps one of the lowest of any hydroponic plant. On the other hand, most recipes only require a few strands of dried saffron, so production from a square foot of growing space is usually sufficient for most gourmets.
What is Saffron?
There are many imitations and cheap substitutes for saffron on the culinary market. Some of these consist of counterfeit strands while others are just color substitutes of cheaper spices such as turmeric. Saffron, although having a long shelf life, is best used within a year of drying and it is difficult to tell if product many years old is being sold as top quality spice. Nothing equals the intense color and subtle flavor of true saffron and some even claim that there are slight flavor variations between saffron grown in different regions of the world. Saffron is the world’s highest priced spice and is often sold by the gram or half gram of the best quality product. As with most crops, it is likely that the growing conditions, soil type, nutrition, temperatures, plant health and harvesting, handling and drying practices play a major role in the final quality and flavor of this spice. Hydroponic production where we have control over basic nutrition and supplements and indoors where temperature, light and the growing environment can be manipulated, give the potential for some extremely high quality saffron to be grown.
The Saffron Plant
The saffron crocus (Crocus sativus L) grows from a small rounded corm (similar to a bulb). The corms are purchased while dormant, and planted out in late summer or early fall when they rapidly burst into life with the production of small crocus flowers. This exotic spice is made from the dried red-gold stigma which forms inside the blue/purple flower. Each flower produces on average three stigmas which give three strands of saffron. After flowering, the plant resumes vegetative growth of thin, dark green strap like leaves and then multiplies itself with the production of many small daughter corms.
Nowadays saffron corms are sold by various seed suppliers and nurseries in small quantities for home gardeners to purchase. However bulbs are not usually available year round and are commonly advertised for sale in mid to late summer through until fall. When buying corms for the first time, it is important to realize that like many flowering bulbs, the corms come in size grades from very small (0.6 grams) which would be a non flowering type requiring an additional season’s growth, to very large (24 grams). The smaller corms are usually less expensive, but they may not produce flowers in the first season or produce a much lower yield of saffron and a lower number of daughter corms after flowering. The best planting grade for hydroponics is around 15 grams which is usually over an inch in diameter. The corms arrive dry in a dormant state ready for planting out.
Growing Saffron Indoors
Indoors, there are two ways of running a saffron system – the dormant corms can be purchased, planted, flowered, harvested and the corms discarded, all over a six week period. Or after the short flowering period, the bulbs can be grown on, producing vegetation and new daughter cormlets over a period of many months, until they become dormant in mid summer. The first system means the corms are planted at a high density since they won’t be grown on and multiplied. This sort of bulb ‘forcing’ could also be carried out in solution culture systems such as those used for tulips and other flowering bulbs where the corm is supported with its base in water The second system needs more space for the plants to fully develop and many months of caring for the corms after they flower, although the reward is a supply of new corms which could be sold or given away to others and a higher yield of flowers in the next year. Tying up your hydroponic system with vegetative saffron for nine to 10 months however may not be attractive to those with limited space, although trays of saffron plants are cold hardly and can be put outside for winter and spring if necessary.
Corms can be stored in a dry place and planted out when the hydroponic system is ready. The spacing should be approximately four to five inches apart and 1.5 to two inches deep, in a tray of free draining, sterile growing media such as coconut fiber with some perlite mixed in. The media needs to support the plants, but at the same time be friable enough for the young corms to form without deformities so any substrate used for baby root crops would be suitable.
The flowers will have already been initiated in the corms during the summer dormancy period and flowering will occur when moisture is provided and temperatures start to drop in fall. Flowering is triggered by environmental conditions such as temperate and moisture which is easily manipulated in a hydroponic grow room. The ideal conditions during flowering are 16 hour day length with day temperatures of 62°F and night temperatures of 53°F. An indoor grow room or greenhouse situation means the flowers are protected from rain, moisture, wind and the lack of weeds makes harvesting of high quality flowers much easier.
The Grow Room
After flowering the foliage grows best at 60 to 65°F, with 12 to 14 hours of light to keep enough photosynthesis going to bulk up the developing cormlets. Saffron typically flowers in autumn over a short period, then produces a number of strap-like leaves which grow through winter, spring and into summer, providing food reserves for the corm and developing new cormlets. After flowering and harvest in autumn, foliage will develop quite rapidly and during this time, a standard vegetative nutrient should be given to the plants as required. Recommended EC levels are 1.2 – 1.4 during this stage. Leaf growth will continue until summer when the young corms start to rapidly develop around the mother corm.
In their natural environment, the saffron plants’ foliage dies back in mid to late summer, after the young corms have matured and as conditions become very warm and dry. The corms then go into a dormancy period which is essential for initiating the next season’s flowers which will bloom in the cooler, moist conditions of fall. In hydroponics we can easily replicate this by drying the media back after the cormlets have formed and the foliage has died down. Having a dig around one of the plants will soon reveal if the corms are ready for harvest and dormancy. The tray of saffron corms, once fully dried, can be harvested and stored away in a dry, dark place until they need to be planted out for flower production. This is a time consuming process as the saffron plant needs many months (nine to 10) after flowering, until harvest of the new corms with only one harvest of flowers per year obtained. However, each mother corm, after flowering will produce a number (four to 10 or more) young cormlets that can be used to produce more flowers and greater harvests of saffron spice in the following season.
Flowering and Harvesting Saffron
Flowering of the corms will typically occur quite quickly after planting; within a few weeks the first emerging flower buds should be seen. The flowers will fully open within three to five days and be ready for harvest. As each flower blooms, it should be plucked or snipped from the plant and taken away for processing. Inside the flower there will be two or three thinner dark red colored stigmas which form the saffron spice when dried; there will also be three, shorter, wider, golden colored anthers which usually have pollen on their surface – these are not part of the spice and should be discarded. The easiest way of removing the saffron stigmas from the centre of the flower, is to pull back and remove all the petals and then snip the red strands at the base. These will then need to be dried before storage. Saffron is very delicate and the strands should be placed on white paper and allowed to air dry and fully desiccate. Any slight breeze will blow the strands away and home dehydrators are not well suited to this. Being small and very light, the saffron will dry within a week in most cases and can then be stored in air tight glass jars. A small package of silicon desiccant can be used to make sure any additional moisture on the strands or in the air does not cause any storage problems. Insufficiently dried saffron can go moldy, so additional air drying time is recommended if humidity levels are high.
While it has become possible for home gardeners to grow a container or pot with a few saffron bulbs outdoors, often just for the novelty of seeing the flowers, there has not been a great deal of research into hydroponic or aeroponic production of this spice. It is likely that the best system will be similar to the hydroponic production of forced tulips and other bulbs with the actual flowering phase being carried out indoors or under protection to give the highest possible blooms, while the plants are propagated and bulbs grown outdoors through until dormancy. Outdoor producers are restricted to one crop of saffron per season, however with an indoor grow room, the environment can easily be manipulated to give the dry warmth of summer to initiate flowering followed by cooler, damper conditions to induce flowering whenever it is required.
The Growth of Saffron (Crocus sativus L.) in Aeroponics and Hydroponics. Fredric V Souret and P J Weathers. Published in: Journal of Herbs, Spices and Medicinal Plants, Volume 7, Issue 3, 2000. ISBN 1049-6475
Supplies of saffron corms: