In short
- Site: full sun, very well-drained soil, neutral to slightly alkaline.
- Blooms in AUTUMN (X–XI) — one of the few autumn-flowering crocuses.
- Corms are planted in VIII–IX (not in autumn like the spring crocus).
- Stigmas are harvested in the morning just after flower opens, by hand — 150 flowers = 1 g dried saffron.
- In summer dormancy, corms MUST stay dry — excess water causes rot.
- 1 kg of dried saffron requires about 150–170 thousand flowers — hence the most expensive spice in the world.
Botanical data
- Family
- Iridaceae (Iridaceae)
- Height
- 0.1–0.2 m
- Width
- 0.05–0.1 m
- Habit
- Clump-forming
- Growth rate
- Moderate
- Position
- Full sun
- Soil
- Humus-rich, Sandy, Loamy
- pH reaction
- pH 6–8
- Moisture
- Moderate
- Bloom
- October–November
- Hardiness
- USDA 6a–9b
- Propagation
- From bulbs / tubers
Characteristics
A low (10–20 cm) bulbous perennial with rounded, flattened corms enclosed in a brown papery tunic. Narrow, grass-like leaves with a white central stripe emerge with or just after the flowers. Flowers are solitary, rising directly from the corm on a short tube, with six reflexed, ovate lilac-pale tepals with darker veins. Inside: yellow stamens and a single style ending in three long (2–3 cm), thread-like, crimson-red stigmas — these are the valuable spice. The plant is a sterile triploid: it produces no seed and propagates only vegetatively by daughter corms, which in commercial cultivation requires annual lifting and replanting.
Growing and care
Watering
During summer dormancy (VI–IX) corms must stay DRY — excess water causes rot. Water only gently after planting and during autumn flowering in a dry season.
0Fertilizing
A 2–3 cm layer of mature compost or fertiliser per the manufacturer's instructions. Avoid nitrogen — it promotes leaves at the expense of stigma formation.
Planting
Very well-drained soil; on heavier sites, add gravel or sand beneath the corms. Full sun site, sheltered from wind. Corms are planted at three times the corm's height (about 10 cm).
Pruning
Remove dried leaves by hand after they wither on their own.
Companion plants
Good companions
Both species love full sun, well-drained soil and a dry summer rest — matched site requirements.
Bad companions
During summer dormancy the saffron corms must stay dry — proximity to perennials needing regular summer watering (hostas, astilbes) causes corm rot.
The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.
Toxicity
| For whom | Level | Notes |
|---|---|---|
| Dogs | Mild | Large quantities of corms can cause vomiting and diarrhoea. |
| Cats | Mild | — |
History and origin
Saffron has been cultivated for at least 3,500 years — the earliest evidence comes from Minoan Crete (Akrotiri frescoes, 16th c. BC). It was used in ancient Egypt, Persia, Greece and Rome as a spice, textile dye and medicine. Phoenicians spread it around the Mediterranean; Arabs brought it to Spain in the 8th century (hence Spanish azafrán from Arabic az-zaʻfarān). In the Middle Ages it was more expensive than gold — in 14th-century Basel, saffron theft was punished by death. Modern cultivation is concentrated in Iran (>90% of world production), La Mancha in Spain, Kashmir and Greece. Wholesale price 3,000–15,000 EUR/kg depending on quality.
Uses
Culinary: the classic seasoning for risotto Milanese, paella, bouillabaisse, oriental pilaf and Swedish lussekatter buns for St Lucia. A pinch (5–10 stigmas) is enough for 4 servings. Ornamental: for beds, edging and containers in dry summer sites. Naturalises well in dry Mediterranean turf — in the UK and central Europe requires winter mulching (leaf litter) in regions below zone 6.
Trivia
- The species name sativus means cultivated — as in many crop plants (Allium sativum garlic, Oryza sativa rice).
- A single flower yields only 3 stigmas — one gram of dried saffron requires about 150 flowers, one kilogram about 150–170 thousand.
- Saffron dyes water intensely yellow in tiny amounts — the pigment is crocin, a carotenoid derivative.
- Unlike the spring crocus, saffron blooms in autumn without leaves or just before they emerge — corms bought in August will bloom in October–November of the same year.
Frequently asked questions
Can saffron crocus be grown in the UK and central Europe?
Yes, in regions in USDA zone 6a and warmer, in a sunny site with very well-drained soil. In colder regions corms are lifted before winter or grown in pots that overwinter in a cold, dry room. A wet winter is the main enemy of the crop.
When do you harvest saffron stigmas?
In the morning, just after the flower opens on a sunny day, plucking the three red stigmas out of each flower by hand with tweezers or fingers. Dry them immediately in shade on paper or in a dehydrator at 40°C for 15–20 minutes. Properly dried stigmas are springy, deep red and intensely fragrant.
How is saffron different from the spring crocus?
In flowering time and use: Crocus sativus blooms in autumn (X–XI) and produces edible stigmas — a spice. Crocus vernus blooms in early spring (II–IV) and is purely ornamental, slightly toxic. Corm planting also differs: saffron is planted in VIII–IX, spring crocus in IX–X. Both should NOT be confused with autumn crocus (Colchicum autumnale) — strongly toxic despite similar appearance.
Sources
- Plants of the World Online (POWO) — Crocus sativusDatabase (GBIF, POWO…)
- RHS — Crocus sativus growing guideInstitution / botanical garden
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