With shoots appearing above ground, and soon flowers pushing through, a journey around this diverse plant family seems timely.
Crocus: etymology (probably) Sanskrit kunkumam Arabic kurkum Hebrew karkom Greek krokos Latin crocus, Old English croh, all meaning “saffron”.
Saffron, with its apposite nickname of “red gold”, was always a valued spice. During the Black Death it was touted as a cure, leading to “The Saffron War”, in which Austrian nobles sparked a fourteen-week conflict by intercepting a shipment bound for Basel in neighbouring Switzerland. Pirate raids on saffron cargoes were hardly rare, not least since it was more valuable than gold. Today, Iran produces more than ninety-five per cent of the world’s saffron harvest, though it is claimed that the Afghan product is superior, and some is even grown in England (around Saffron Walden, naturally). All is hand-picked: more than 150,000 flowers are needed for one kilogram of the dried spice. Top-quality saffron retails at up to £75 per gram, and there is widespread adulteration.
Merely decorative types of crocus have been grown for at least four hundred years. Other than the autumn-flowering Saffron Crocus (Crocus sativus) the great botanist Carl Linnaeus named only one other species in his seminal classificatory book Species Plantarum of 1753: the spring-flowering C. vernus. More modern botanists have listed up to 160 different species, plus many varietals for garden use. Most flower in spring, but the Saffron Crocus is not the only autumn-flowering species. Incidentally, do not confuse those with the plant often called Autumn Crocus, or “Naked Ladies” – presumably because it flowers “nakedly” without leaves, which emerge in the spring. Though it looks like a crocus and has another common vernacular name of “Meadow Saffron”, Colchicum autumnale is actually part of the lily family, whereas true crocuses are related to irises. All most confusing …
With careful choosing, you can have crocuses flowering in your garden from October till April. The colours range from pure white through yellow to blue and purple. There are some bronze ones, and some pinkish ones, but “true” red is unknown. Autumn-flowering crocuses need to be planted in mid- to late summer, which may account for their comparative rarity in gardens, since there is so much else happening at that time of year – a pity, since many repay the gardener’s trouble abundantly. I would recommend C. speciosus (lilac-blue), C. niveus (white), and, if you can find it, the Greek species C. tournefortii (pale lilac), which, unusually for a crocus, will open in cloudy conditions and stay open all night – most crocus require sun to open fully. Of winter/spring varieties, one of the earliest to flower in Britain is Crocus tommasinianus, a native of Hungary and the Balkans, which is only about 3 inches (8cm) tall, but is a cheering sight in late winter – no wonder it is often called the “snow crocus”. There are purple and white forms. Crocus chrysanthus also flowers early, and is fragrant. There are several varietals available, ranging from pure white (“Polar Bear”) to bronze/purple/yellow (“Advance”) or purple and white (“Herald”). Of the many species and varieties flowering a little later, some of the best are “Orange Monarch” (orange with bronze stripes), “Pickwick” (purple and white stripes), and “Jeanne d’Arc” (large pure white).
In general, crocus are not fussy plants, though they do need sun. The one thing they really hate is wet soil, so don’t plant them in unimproved clay, they’ll rot. The corms should be planted about three times their depth in well-drained soil, then watered in, and allowed to “do their thing”. Many varieties naturalise very well in grass, and, as I’ve recommended before with daffodils, the best way to plant them, whether in beds or lawns, is to throw a handful into the air and plant them where they land. This will ensure a more natural look – regimented crocuses can be great in a densely-packed container, but not otherwise. If happy in your flower-bed they can increase, by seed or cormels (baby corms), so might need splitting after a few years if they get crowded – do this after flowering, which is also the time for a dressing of bonemeal to help the plants build up nutrients before their summer dormancy. As with so many garden plants, do not let small children or pets eat crocuses, since they can cause a nasty stomach upset. Colchicums are worse: they contain the alkaloid colchicine, which can kill humans, dogs ... and cows.
Corms of spring-flowering crocus are always available in late summer in nurseries and garden centres, and there are specialist nurseries for the more unusual types. As well as large companies like Jacques Amand, I recommend Potterton’s (pottertons.co.uk) and Rare Plants (rareplants.co.uk)