Planting saffron in the garden

It is the most expensive spice in the world – saffron. We show you whether and how you can grow this unusual spice in your own garden. Find out all about planting saffron in this article.

With the addition of saffron (Crocus sativus) dishes are not only seasoned, but refined. A single gram of the valuable spice costs 10 to 20 euros, depending on the quality. Crocus sativus also thrives at our latitudes, even if it cannot often be harvested. We give tips on planting, care and use of saffron.

Saffron: origins and characteristics

Its origin is the perennial saffron from the iris family (Iridaceae) in the Aegean Sea. It is grown mainly in warm Mediterranean regions and the Middle East. Saffron was created only by chance from a mutation of the related crocus species Crocus cartwrightianus. This led firstly to the development of larger flowers, but also significantly longer and larger pistil filaments, on which the stigmas are located. It is precisely these characteristic, long, deep red saffron threads that are relevant for saffron cultivation. They contain the slightly bitter, spicy saffron aroma and the strong colouring power. These saffron threads are formed during the flowering of the purple saffron in October-November. However, the sensitive pistils do not tolerate temperatures below 15 °C, and so the spice of saffron can actually only be harvested in very mild wine-growing regions. In all other areas, however, planting saffron is worthwhile simply for its ornamental value, low maintenance and late flowering time, which reminds us of the crocus bloom earlier on in spring.

Even though saffron is sometimes referred to as autumn crocus, it is important to differentiate it from the highly toxic Colchicum autumnale. Read our separate article covering the poisonous autumn crocus to find out more about its identification and cultivation.

Cultivating saffron

Cultivation of the precious saffron plant is not easy, because it is very demanding in terms of its location. However, the cultivation of the expensive spice can also be successful in certain cases in protected and warm locations in our domestic gardens. But to be able to harvest a considerable quantity at all, about 150 flowers would have to be grown for 1 g of dried saffron threads.

The right location

Saffron plants prefer dry, sunny locations on loose, sandy and calcareous soils. Waterlogging must be avoided at all costs, otherwise the tubers and roots will quickly rot in the soil. Whether in a pot or bed, the saffron prefers to be protected from the wind and to be warm. This increases the chance of being able to harvest the threads in the autumn. For this, Crocus sativus needs constant temperatures of around 15 °C during flower formation, even in September and October.

Planting saffron

Saffron is propagated exclusively vegetatively, so you plant small saffron tubers directly into the ground. The small tubers can be placed directly in the ground or a pot from July to the end of August. For the cultivation of saffron in a pot, the planter should be sufficiently large, which will facilitate fertilisation later. For a single tuber, which also reproduces underground in late autumn and forms daughter tubers, the pot should hold at least 10 litres. For pot culture, a nutrient-rich potting soil is particularly recommended. Instead of climate-damaging peat, we recommend a soil with a high compost content, which retains moisture and provides long-term nutrients. The planting soil should be enriched with at least 30% sand, perlite, lava rubble or coarse brick rubble. At the bottom of the pot, a drainage layer of at least ¼ of the pot height should be filled in. For this purpose, for example, brick rubble, expanded clay or even pebbles are suitable.

The saffron tubers are placed at a depth of 15 cm, with the planting tubers about 15 cm apart. To protect the tubers from voles, a vole basket can be used at planting time.

Caring for saffron

After planting, saffron initially does not require irrigation, because the tubers contain enough water for root development and sprouting. As growth continues, occasional watering during extreme heat and drought in late summer September is quite sufficient to take care of the tuber for the energy-sapping flowering. In the dormant period from May to August, saffron should not be watered at all, because now it has neither leaf nor flower.

If saffron is cultivated in a pot, an annual application of slow-release fertiliser, such as our Plantura Flower Food, provides the necessary nutrients for a magnificent flower and vigorous green foliage. The fertiliser can either be added each spring when repotting or simply worked flat into the surface of the potting soil with a fork. Even when growing in mature soil, some organic fertiliser can be dug under in the spring.

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It is recommended that saffron be repotted or planted in a different location every 3 to 5 years. Digging and transplanting should be done in the dormant season from April to September. The chive-like foliage remains in winter and, depending on temperature and weather, does not emerge until April.

Tip: Saffron plant is perennial and with good care will delight you for many years. However, it is also self-incompatible. The same area should be left uncultivated for 10 years before planting new saffron.

Propagating saffron

The iris plant, which is about 10 to 15 cm tall, has a triple set of chromosomes due to its unusual genetic origin. It is therefore sterile and cannot form germinable seeds. Saffron cannot therefore be propagated by seed because there are no saffron seeds. The only method of reproduction is through daughter tubers. After the saffron flowering in late autumn, the crocus vegetatively forms small tubers that have exactly the same genetic material, i.e. are natural clones of the mother plant. They can be dug up after the foliage dies in April and transplanted individually. In good conditions, the number of daughter tubers doubles every year and so saffron can be multiplied quickly.

Overwintering saffron

Relatively hardy saffron tolerates temperatures in the ground up to -10 °C, at lower temperatures it becomes critical. A cover of fir branches or a thick layer of leaves can provide additional protection from the cold temperatures. Saffron tubers planted in pots should be overwintered indoors frost-free, but must be kept cool and with only a few waterings.

Saffron as a spice: use and constituents

Saffron has a strong seasoning and colouring power, so it should only be used in moderation in cooking. The three main components crocin, picrocrocin and safranal are contained in the threads. The latter is largely responsible for the typical smoky-spicy flavour of saffron. Crocin and other plant pigments, such as xanthophylls and carotenoids, colour rice and pasta dishes, liqueurs, cosmetics and baked goods a sunny yellow. At an excess dose, however, the bitter substances of saffron, which are also present, quickly come to the fore and above a daily dose of 1.5 grams, hallucinations, convulsions and even death can occur. However, this amount is never exceeded if the saffron is used only in the kitchen as a spice. In folk medicine, the expensive spice is still used as a remedy today. The effect of saffron is mood-lifting, calming, digestive stimulating as well as fever reducing and it is an important ingredient in Swedish herbal elixirs.

Tip: Saffron is slightly toxic. Inedible substances are contained in the tubers of saffron, just as in the stigmas of the flower. Therefore, the plants should not be consumed.

If planting and care is successful, Crocus sativus will reward you in October with its deep purple flowers and pretty saffron threads. If you are lucky and have very green fingers, it is then on to the saffron harvest and subsequent drying and storage. Learn more about this in our special article.