What is a colchicum?
Large-flowered colchicums flower without their leaves throughout autumn, offering an injection of colour. The Colchicum flowers vary in colour from white to pale pink and dark purple and can be narrow and slim to large and sturdy goblets on sturdy stems. There are multi-petalled colchicum selections in white and purple.
During the 20th century the great gardener and author EA Bowles championed the genus in his book A Handbook of Crocus and Colchicum for Gardeners published in 1924 with a revised edition in 1952.
Bowles was a stickler for correct nomenclature and often bemoaned the fact that colchicums were so inaccurately named. The underlying challenge for botanists is the seasonal difference of colchicum flowers in autumn and leaves in spring.
The cultivar Colchicum ‘Autumn Queen’, a fine early flowering, well-marked cultivar, is now well over 100 years old. Today there are about 70 named colchicum cultivars and 35 autumn-flowering species. Many of the species are difficult to grow.
There are also spring-flowering, mostly species colchicums. Colchicums are large, cormous plants with brown tunics that mainly flower in autumn. Commonly known as naked ladies, autumn crocus, and in the USA as false autumn crocuses, which is more accurate.
Origins Asia and Europe, usually in high-altitude meadows.
Size Colchicum flowers 10-30cm tall in autumn, leaves as tall and spreading in spring.
Conditions Sunny or half-shady position in borders and shrubberies, ideal in long grass, which is only mown from June until the end of August.
Hardiness rating Most have a rating of RHS H5 and are suitable for gardens in USDA zones 4a-8b. Holds an Award of Garden Merit from the Royal Horticultural Society. Hardiness ratings given where available.
The best colchicums for your garden
Colchicum ‘Autumn Queen’
One of the first autumn-flowering colchicum cultivars to flower. Often nosing through in late August with mid-sized flowers, which thrive in a sunny site. 18cm. AGM. RHS h5, usda 4a-8b.
Colchicum x agrippinum
This highly tessellated colchicum selection is a hybrid of unknown parentage. It has hybrid vigour with demure leaves in spring. 10cm. AGM. RHS H4.
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Colchicum byzantinum ‘Innocence’
An albino cultivar, singled out from a Colchicum byzantinum bought from Van Tubergen nursery in the 20th century, Vigorous and floriferous. 15cm. AGM. RHS H5.
Colchicum ‘Benton End’
A substantial colchicum flower of quite a dark purple. It was found in the eponymous Suffolk garden of the artist Sir Cedric Morris, who was famed for his bearded irises. 18cm.
Colchicum ‘Pink Goblet’
Found by Dick Trotter in his garden Brin near Inverness. This true-pink plant, which smells of honey, was selected from a sowing of Colchicum speciosum ‘Album’ seed. 20cm. AGM. RHS H5.
Colchicum byzantinum ‘Pink Star’
A slim-petalled colchicum flower that can produce up to a dozen flowers per corm. The collective impact is delightful. Bulks up quickly. 15cm. AGM. RHS h5.
This large and growable selection of Colchicum cilicicum, is named for the National Trust Garden in Norfolk, but was found in Myddelton House, EA Bowles’s garden, in Enfield. 14cm. AGM.
Colchicum autumnale ‘Alboplenum’
This multi-petalled, white colchicum is short and quite weatherproof. The flowers are very long lasting. Widely available. 15cm.
Colchicum ‘EA Bowles’
Found in the peach border at Myddelton House after Bowles’s death. A mid- season plant with a strong purple sheen to the petals and an imposing presence. 20cm.
The only multi-petalled, dark-pink, large-flowered cultivar. A Dutch seedling – apparently a cross between Colchicum autumnale ‘Album’ and Colchicum speciosum ‘Album’. 15cm. AGM. RHS h5.
Colchicum ‘Rosy Dawn’
A late-flowering cultivar raised by Barr & Sons Nursery over 70 years ago. Very strong and often fertile, so seedlings will eventually occur. 15cm. AGM. RHS H5.
Colchicum cilicicum ‘Purpureum’
A strong, late-flowered colchicum cultivar, dwarf in stature with short, quite glossy, dark-green leaves in spring. Widely available. 10cm. AGM. RHS h5, USDA 4a-8b.
Colchicum autumnale ‘Nancy Lindsay’
This colchicum was collected nearly 100 years ago by Nancy Lindsay in Romania as she travelled back from a plant collecting trip. 10cm. AGM. RHS h5, usda 4a-8b.
Colchicum speciosum ‘Rubrum’
A diminutive Colchicum speciosum with flowers that are like small glass flutes on slim perianth tubes. The foliage, however, is typical of Colchicum speciosum. 20cm.
It has the dubious virtue of being the strongest plant in the recent colchicum trial at RHS Hyde Hall. Its leaves rival some veratrums in its size. It is also extremely floriferous. 18cm.
When to plant Colchicum
Colchicums are best planted from June until August when they are dormant. When planting, the top of the dry, brown tunic should be just above soil level. Colchicums thrive in heavy soils and even do well on sandy loams. To keep them growing well, it’s a good idea to lift and split the group every three to four years.
Colchicum generally suffer from few diseases but in damp summer weather they can be damaged by the keeled slug, a small slug that lives between the corm and the tunic. This only becomes a problem if the emerging bud is eaten. The whole plant is toxic to humans and animals.
If left in situ for many years the colchicum tunics form layers rather like a Russian doll and inhibit the size of the new corm. The white flowers of Colchicum speciosum ‘Album’ can look amazing planted among Ophiopogon planiscapus ‘Kokuryu’.
In grass, the large-flowered colchicums are in their element. In traditional orchards or wildflower meadows they flower well and are supported by the surrounding grass. This does mean that you will need to leave the grass uncut from the end of August until late June. Although, in some years the grass could be cut in November to December and do no damage.
A peculiar characteristic of colchicums is when cut for indoor display they do not need water, and will last well in their dry state in a vase and adding water does not extend their life; you can even grow the corm indoors on a windowsill, without any compost or pot and it will still flower.
Where to see and buy Colchicum
- Avon Bulbs, Burnt House Farm, Mid Lambrook, South Petherton, Somerset TA13 5HE
- East Ruston Old Vicarage, East Ruston, Norwich, Norfolk NR12 9HN, Open Wednesday – Sunday, 12-5.30pm, until 26 October
- Rare Plants, PO Box 468, Wrexham, Clwyd LL13 9XR
- RHS Hyde Hall Garden, Creephedge Lane, Chelmsford, Essex CM3 8ET, Open 10am-6pm
- RV Roger Ltd, The Nurseries, Malton, Road, Pickering, North Yorkshire YO18 7JW
- Witton Lane Seeds, 16 Witton Lane, Little Plumstead, Norwich, Norfolk NR13 5DL
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