Family: Iridaceae

These pretty corms bloom either in autumn, winter or spring in a large range of colours including white, yellow or lilac. The flowers are shaped like goblets and the leaves are grass-like, with a single, white stripe down the centre. Many garden hybrids have also been developed, these being mostly of Dutch origin. Commercial saffron used for colour and flavoring, particularly in Indian dishes, comes from the dried red-yellow-orange stigmas of Crocus sativus. Saffron is the most costly spice in the world; 75,000 flowers are required to make 30 grams (1 oz) of pure saffron.

Species

Autumn Flowering

C. kotschyanus, zone 5, to 8 cm (3 in), has rosy purple flowers.

C. serotinus subsp. salzmannii, zone 6, to 6 cm (2½ in), has silvery lilac flowers.

C. sativus, saffron, zone 6, to 12 cm (5 in), produces purple-based, lilac flowers with long, brightly coloured stigmas. It is worth trying in warmer areas.

C. speciosus, zone 4, grows to 12 cm (5 in), with bright lilac flowers, feathered with purple. Cultivar 'Albus' produces white flowers and scarlet stigmas; 'Cassiope' has blue flowers, with yellow at the petal base; and 'Oxonian' has deep violet-blue flowers.

Late Winter Flowering

C. biflorus, Scotch crocus, zone 4, grows to 10 cm (4 in), with white to lilac flowers. In some areas this particular species flowers in the spring.

C. chrysanthus, zone 4, growing 5-8 cm (2-3 in), generally produces yellow flowers, but they can vary from white to lilac. Numerous choice cultivars are available, including 'E. A. Bowles', with rich yellow flowers; 'Snow Bunting', with white flowers; 'Blue Pearl' and 'Cream Beauty'.

C. imperati, zone 7, grows to 8 cm (3 in). Its flowers are coloured purple on the inside and fawn on the outside, with purple feathering.

C. tommasinianus, zone 5, one of the more easily cultivated species, grows 6-8 cm (2½-3 in). Its flowers are lavender on the inside and pale gray on the outside. Cultivars include 'Barr's Purple' and 'Ruby Giant'.

Spring Flowering

C. vernus, Dutch crocus, zone 4, is a variable species, growing to 8 cm (3 in), bearing white to purple flowers which are sometimes feathered. It does particularly well in rock gardens or under deciduous trees. Cultivars of the large Dutch crocuses will grow to 12 cm (5 in) and they flower early in the season. The cultivars include 'Jeanne d'Arc', with white flowers, purple at the base; 'Little Dorrit', with silvery blue flowers; 'Pickwick', with silvery blue flowers which are striped in deep lilac; 'Queen of the Blues', with lavender flowers which are purple at the base; and the cultivar 'Remembrance' which produces violet flowers.

Cultivation

Crocuses thrive in a light, rich, well-drained soil in full sun, but they will also grow in most soils and in partial shade. They are suitable for planting amongst grasses, in rockeries or in pots. Plant the corms about 8 cm (3 in) deep, with a similar distance between plants, in the late summer for autumn-flowering kinds, and in the autumn for the winter-and spring-flowering crocuses. Leave undisturbed unless they become congested. Corms can be lifted when the foliage dies down. They can be grown from seed sown in autumn, but they will generally take two to three years to produce flowers.

Climate

There are crocuses suited to various climatic zones.