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By Pat Cook, Master Gardener, SCMG

Autumn Crocus Colchicum autumnale

Colchicum autumnale, commonly called Autumn Crocus or Meadow Saffron, is a cormous perennial that blooms in early fall.  An under-used fall bloomer, autumn crocus is a terrific addition to the fall garden. Autumn Crocus adds unique colour to the garden when most perennials and shrubs are getting ready for winter.

Autumn crocus has an unusual life cycle in that its foliage appears in the spring when tulips, daffodils, and crocus bloom.  Its leaves die down in early summer and the plant remains dormant underground until fall.  Flowers with no stems or leaves rise from corms in late September or October.  This growth habit has earned these flowers the nickname “naked ladies.”  Each stem bears a lavender pink to lilac-pink star-shaped flower.  The flowers are quite delicate and last only a few days.  Large Colchicum corms can have up to 6 flowers which open over a period of several weeks.

Although Crocus and Colchicum have similar flowers, Colchicum is unrelated to the true crocus.  Autumn Crocus is in the Colchicaceae family (formerly included in Liliaceae family); crocus is in the Iridaceae family.  Autumn Crocus flowers tend to be much larger than spring crocus.  Other differences between Crocus and Colchicum are the flowers of Autumn Crocus have six stamens and the leaves are wide and solid green.  The flowers of crocus have three stamens and their leaves are narrow and grass-like.

Also known as meadow saffron, C. autumnale is toxic if ingested, and must not be confused with the saffron crocus, Crocus sativus, from which the gourmet spice saffron is derived.

C. autumnale develop from a corm, which should be planted in late summer or early fall. Plant the corms in an area where the short flowers can be enjoyed, but where the taller spring foliage will not interfere with other perennials. The flowers are quite delicate and should be protected as much as possible.  They perform best in sheltered locations where afternoon sun encourages a succession of blooms.  In deep shade they still flower, but with fewer blossoms.  Once planted there is very little care required – they are basically maintenance free.

Colchicum corms can be dug up and divided every few years to increase the number of plants.

Grow colchicum in moisture retentive, humus rich, fertile but well-draining soil. Like most other bulbs, these beauties are intolerant of sitting in heavily wet soils.  Set them 8-10 cm (3-4 in) deep and about 4-6 inches apart.  After flowering, apply a top dressing of garden compost.  The corms will naturalize with time.  In the spring allow the foliage to die back naturally as this replenishes the corm for the next seasons bloom.

There are several species of fall flowering crocus which also flower in the fall.  These are not Colchicum, but rather they are relatives of spring flowering crocus.

References:

https://gardenerspath.com/plants/flowers/grow-autumn-crocus/

https://www.gardenfundamentals.com/colchicum-autumnale/