Colchicums 101

A neighbor came over and I showed the leaves to her. "Oh, I have them in my garden, too. The leaves will die back in summer. Then, in the fall, these crocus-like flowers will bloom, kind of pinky-purple. But I don't know what they're called." From my winter-long study of the White Flower Farm catalog (no internet back then), I thought I remembered a similar description. I looked it up and sure enough, they were colchicums, a cormous plant with a summer-dormant period and, typically, a fall bloom.
At first, I was content to observe these plants through their life-cycle. After a couple of years, I noticed White Flower Farm was not the only place selling these bulbs, and I started adding more kinds to my garden. I currently have a mix of over fifty species and hybrids and compulsively add newly listed varieties to my collection. Yes, I’m a colchicophile.
Before we get into the weird and wonderful ways of colchicums, I’d like to get something off my chest. Please don’t call these plants autumn crocuses. They are not crocuses. They are in the Colchicaceae family, not the Iridaceae as crocuses are. Colchicums have three styles and six stamens; crocuses have one style and three stamens. And colchicum leaves are much broader than crocuses’ grass-like leaves. Furthermore, there are bonafide crocuses that bloom in the fall as well as colchicums that bloom in spring. Readers of this journal are more comfortable with botanical names than the average gardener, so I doubt colchicum is too much of a mouthful for you. They have many amusing common names (naked ladies, naked boys, sons-before-the-fathers, among others) so when speaking with someone averse to botanical Latin, you need not resort to something confusing like “false autumn crocus”.
Colchicums bring an element of freshness and surprise into the autumn garden. Most plants that bloom in autumn have been growing all season, and while their flowers may have just opened, their leaves and stems are worn and tattered. Colchicums, on the other hand, emerge with no advance warning, no sign to the casual observer that a plant was growing there, and suddenly there they are, pristine and pretty. Occasionally someone who has inherited colchicums when they bought their home doesn’t even realize the leaves and flowers belong to the same plant.
The morphology of the flowers is a little strange. They have no stem, only a tube of tepal tissue called a perianth tube that goes all the way down to the corm. The flower’s ovary is underground. If seeds are formed they will emerge above ground the following year in a pod nestled among the leaves.
Colchicums contain a chemical, colchicine, that makes them poisonous to deer, rodents, and humans, although colchicine used to be a common treatment for gout. Slugs do dine on the leaves and flowers, though in my garden this is only a sporadic problem. Colchicums prefer full sun but seem to tolerate any aspect except full, deep shade. The most common varieties are happy in average soil, but the fussier ones prefer well-drained soil. If I’m having trouble growing a new one the first thing I will do when I try again is improve the drainage.
Colchicum are unusual, fun, and relatively easy to grow: why don’t more people grow them? One downside is that, compared to the flowers, the leaves are huge, and when they go dormant, they make a mess. In my garden, while the colchicum leaves are turning yellow and flopping over, the peonies, bearded irises, and Oriental poppies are in peak bloom. If you don’t site them properly, those floppy leaves are not just unsightly, they can smother surrounding plants. For some people, this is a deal-breaker. I prefer to think of it as a design challenge.
​ Best for beginners
If you’re just getting started growing colchicums, begin with one or more of the following. These colchicums in particular have been growing in gardens for decades—sometimes centuries—multiply rapidly, and tolerate a wide range of conditions. For nomenclature, I follow Colchicum: The Complete Guide by Grey-Wilson, Leeds, and Rolfe (see the review in this issue). All of them are listed as hardy to USDA Zone 3 by a Wisconsin bulb seller, except for C. x byzantinum, which is hardy to Zone 4.
Colchicum x byzantinum is the one I discovered growing in my first home. Any bulb that can survive ten years of neglect, USDA Hardiness Zone 4 winters, and clay soil, is one tough plant. Individual lavender-pink flowers are small but come up in bunches so the effect is showy. It was first described in 1601 by Clusius, who got his corms from some Viennese ladies, who in turn got them from someone from Constantinople (Byzantium). Talk about plant swapping! Since C. x byzantinum does not set seed, all of the corms in the world are descended from those originally from the Byzantine empire. Growing it is having a piece of history in your garden.
C. x byzantinum ‘Innocence’ is pure white at first glance, then you notice that the tips of the styles and the tips of each tepal are touched with purple. There is some debate whether a pure white form exists, but ‘Innocence’ is the only published name. ‘Album’ is supposed to be pure white, but the ones I bought under that name also had purple tips.
Colchicum autumnale is native to moist meadows in Great Britain. Over the centuries many natural variants have been discovered and perpetuated. The straight species is pink and crocus-like in shape. Mine tend to get a bit leggy and I’ve been told they need more sun. ‘Alboplenum’ is a double white form that is very vigorous. It blooms later than the species and spangles the late autumn garden like stars. ‘Album’ is a single white. According to Grey-Wilson et al., several variants go by this name, some of which are whiter than others. ‘Pleniflorum’ is a double pink form that blooms later than the species. However, the hybrid ‘Waterlily’ is much showier and more frequently available. C. autumnale subsp. pannonicum ‘Nancy Lindsay’ is an improved version of the species: sturdier, pinker, and multiplying faster. Even better, the flower color continues all the way down the tube.
Colchicum speciosum is native to the Caucasus, northern Iran, and northern Turkey but was introduced to western Europe around 1850. Like C. autumnale, it has a lot of natural variants and has also been parent to many garden hybrids. It’s a bigger plant than C. autumnale, with a thicker floral tube and a white throat. ‘Album’ is pure white with green filaments and a lime-green tube. Larger and more elegant than any of the other white colchicums, Grey-Wilson et al. says it multiplies freely, but it has been a slow grower for me and it’s not often available in the trade. ‘Atrorubens’ is a darker form with the color extending all the way through the tube. It is not always available, but I find it much more attractive than the straight species.
Colchicum ‘Giant’ (also sold as 'The Giant') is a hybrid, truly head and shoulders above mere mortal colchicums. The pale lavender-pink is not my favorite, but it multiplies very fast and can quickly make a spectacular show visible from across the yard.
Colchicum ‘Waterlily’ really does look like a waterlily, with over 50 rosy-lilac tepals. Try growing it through a ground cover, such as a dark-leaved ajuga.
​ Rock garden potential
I don’t have a rock garden. I have acidic clay soil, one bed I’ve amended to be (hopefully) better-drained, and one trough in which I grow “tricky” colchicums. I’m guessing the following colchicums would be good for a rock garden because either they are petite and less likely to overwhelm their neighbors or I have trouble growing them, presumably because my soil is not free-draining enough. The spring bloomers are also good candidates for a rock garden.
Colchicum x agrippinum has flowers on the small side but they are distinctly tessellated. (Tessellated is the scientific term for checkered.) I smile every time I see them. While these do prefer well-drained soil they aren’t really fussy, and I make them happy by growing them on a slight slope.
Colchicum davisii is pale pink and petite. The flowers I grew had more pointed tepals than those shown in Grey-Wilson et al. The corm looks less like a bulb and more like a lump with legs called soboles.
Colchicum graecum has a pale pink flower and is not very vigorous for me; but hey, it’s still alive and that’s saying something since it’s reputed to only be hardy to USDA Zone 6 and I’m Zone 5. It’s one of the few that bloom in August for me.
Colchicum ‘Antares’ is a slow-grower with charming flowers that are mostly white with pale lilac-pink tips. They bear close inspection which suits them for a rock garden or trough.
​ My favorites
My favorite colchicums are strongly colored. It’s even better if they are distinctly tessellated and the tepal color extends all the way through the tube. I don’t think any of these are fussy, but they’re harder to find.
Colchicum ‘Disraeli’ and the similar varieties ‘Princess Astrid’, (Grey-Wilson et al. says syn. ‘Autumn Queen’),‘Glory of Heemstede’, C. bivonae ‘Apollo’, and ‘Beaconsfield’ (listed roughly in order of bloom time) all have white throats, saturated raspberry color, and distinct tessellation. The differences between them are subtle and they all make visitors exclaim and stroll over for a closer look.
Colchicum macrophyllum has smaller flowers than ‘Disraeli’ but similar coloring with very big leaves in spring. This has proven hardy in my free-draining bed and I look forward to trying it in the regular garden.
Colchicum ‘Jochem Hof’ has flowers that are almond-shaped in bud and deep pink with no tessellation. Grey-Wilson et al. say this is a synonym for ‘Poseidon’ but in my garden they are different in bloom time, flower shape, and intensity of color.
Colchicum cilicicum ‘Purpureum’ is a s smaller, late-blooming flower with no tessellation but a white line through the middle of each vividly colored tepal.
Colchicum ‘Dick Trotter’ has a lovely goblet shaped bloom whose magenta color extends down its tube in a more muted shade.

​ Spring bloomers
By all accounts, the spring-blooming colchicums are more challenging to grow than the fall-blooming ones, and my experience bears this out. You may already grow a spring-blooming colchicum: Bulbocodium vernum, now designated Colchicum bulbocodium. The leaves of spring-blooming colchicums emerge in the spring with the flowers.
Colchicum hungaricum ‘Valentine’ (syn. C. doerfleri 'Valentine') is supposed to be pink but for me, it’s more like white flushed with pink. The similar Colchicum hungaricum ‘Velebit Star’ is white. Both have a bit of hairy fuzz on the edges of the leaves, charming when it holds the dew (or melted snow, as the case may be). I'm on my second attempt at growing both of these. These species blooms in February (near Valentine’s Day) for some people but mid-March to mid-April for me.
Colchicum munzurense, grown in a trough, came back after the first winter when the trough was moved to an unheated, detached garage for the cold months, but did not come back this year when the trough was left outdoors during a mild winter. I had the same experience with Colchicum soboliferum (formerly Merendera soboliferum). Both were considered hardy to USDA Zone 6 from my source and my garden is a cold Zone 5. I’m not sure whether it was the cold or the wet that did them in, but I learned my lesson: get that trough into the garage for the winter! I know a rock gardener in Zone 6 who grows C. szovitsii ‘Tivi’ but hers hasn’t multiplied enough that she’s willing to trade, and I haven’t found it for sale.

​ Colchicums I covet
The life of a colchicophile is full of frustration. Between the images shown on the Crocus and Colchicum Facebook group and the hybrids pictured in Grey-Wilson et al., I have a list of colchicums that I would love to acquire but are not available in the United States. If you have already obtained the permits necessary for importing bulbs, check to see if your vendor can supply any of the following. Once the corms are in the U.S., I’m sure we can agree on terms.
My current wish list includes ‘Artur Clark’, ‘Benton End’, C. autumnale subsp. pannonicum ‘Dorothee Kersen’ (variegated leaves!), ‘Emerald Town’, ‘Felbrigg’, ‘Glory of Threave’, ‘Herbstkugel’, ‘Jenny Robinson’, ‘Kiss Me Quick’, ‘Little Woods’, and ‘Redgrave’.
Oh, who am I kidding? I want them all!