Never mind the Lost Crops of the Incas, skirret (Sium sisarum) seems to be the Lost Crop of the Europeans. Based on my experience, it’s high time it was rediscovered.
Originally from China, skirret was clearly well established in Europe by Roman times. It was a favourite of the Emperor Tiberius, a man who, don’t forget, could have pretty much anything he wanted for his table. He liked it so much that he demanded it as tribute from the Germans. It remained widespread and popular into Tudor times and then… where is it now?
Two crops of European empires may have displaced skirret. The first was the potato. Skirret is a starchy root, a useful staple, but nothing like as productive as the potato (what is?). The second was sugar cane. One of the most striking characteristics of skirret is its sweetness: even the name comes from a Germanic origin meaning ‘sugar root’. Before ubiquitous sweeteners, this would have made it extremely attractive, even to greedy Roman emperors. Whatever the reasons, skirret faded away from gardens, tables and popular consciousness. I’d say that it has several characteristics that make it worth revisiting.
First up, skirret is delicious. It has a floury texture, a little like a potato, due to the high starch levels. Its taste is unique, but vaguely carroty, not surprisingly as it comes from the multi-talented carrot family (Apiaceae). It needs very little cooking. My favourite way of cooking it is to parboil for a few minutes, then fry in butter or vegetable fat. This gives a certain crispiness to the skin, encasing the gooey sweetness of the flesh. Being from Central Scotland, I have of course tried deep-frying it and can report that it makes a passable chip, but it scores higher on taste than texture when cooked this way. Wikipedia has an entertaining section on skirret recipes through the centuries.
Secondly, skirret is quite easy to grow once you know how. Unlike most of its vegetable relatives it is not a biennial with a single taproot but a perennial that produces a whole shaggy bunch of roots. A dormant skirret plant can therefore be lifted, divided and replanted like any clump-forming perennial. Grown from seed, skirret produces a single ‘crown’: several shoot buds around the base of a stem, with a cluster of roots attached. Grown on, this crown will divide to form a clump made from several crowns. The clumps are easy to tease apart into individual crowns again. A cluster of roots will consist of several that are worth picking and a good number that aren’t, so my harvesting method is to dig up the clump, snip off the roots that are worth having, separate into crowns and replant. This leaves the plant with the maximum amount of resources for a good start the next year.
Thirdly, skirret ought to be an easy crop to improve. The combination of annual seed production and clonal propagation by the division of clumps means that new varieties are easy to produce and then maintain. The plants that I have grown from seed show considerable variation in root number, thickness, length and quality. I’d like to see skirret selected to produce fewer, fatter roots with smoother skin (cleaning skirret is something of a faff as the wrinkled skin tends to hold the dirt and require a good scrubbing).
One drawback to skirret is that the roots can have a woody core which cannot be softened by any amount of cooking and which is not particularly practical to remove. Guides suggest that this is a problem of young plants that goes away on older ones, or that it is caused by a lack of water while growing or that it is under genetic control and varies from one plant to another.
I have kept careful records of the qualities of my plants from year to year for the best part of a decade and I don’t think that the thing about older plants is true. Similarly, if there is a magic recipe for growing them without a woody core I am yet to find it. On the other hand there does seem to be a degree of consistency about how prone to woodiness an individual clone is, although this is accompanied by some year-to-year variation. I assume that genetic and environmental factors are interacting in unpredictable ways.
A second yield from skirret is the immature flower stems, which have a very nice carroty taste when boiled or steamed. They are fairly substantial and produced in reasonable volume, but they are fast growing and soon harden off, so if you want more than a brief harvest you will have to freeze some.
Starting skirret from crowns may be easy, but to get a crown in the first place you either have to shell out a fair bit of money or you have to start from seed. Skirret is not the easiest to grow from seed as like many of its relatives it needs a period of winter cold (stratification) to encourage it to germinate. If it is anything like most Apiaceae the seed will lose viability quite quickly, so it is a good idea to source current-year seed in autumn and start stratifying straight away.
For cultivation, skirret seems to like moist, free-draining soil in full sun. It’s said not to like hot weather but this isn’t a problem that I experience much. I’d advise growing it in rich, well-fertilised soil as a poorly fed skirret will produce thin roots that aren’t worth harvesting. Mature crowns need to be spaced at 30cm or more. Giving it a mulch is a good idea to help keep moisture in and suppress early weed growth. I have mine planted in a bed with compost dug in and a mulch of leaves over the top. It will grow up through the mulch and require little to no weeding as its strong growth suppresses weeds later in the season. Skirret can be left in the ground until needed: towards the end of the season, you might want to mark where the plants are as there can be little sign once the leaves die down!