Wednesday, 7 January 2015

Skirret - a forgotten perennial vegetable

I have never met a person who dislikes Skirret (Sium sisarum) and I don't expect this to change.  Very few people in Australia grow skirret or have even heard of this remarkable vegetable, but those that have tried it all seem to like it.
Skirret seedlings still with their juvenile leaves

What is skirret

Skirret is primarily an ancient root vegetable, but the leaves, stems and seeds are also edible and tasty enough in their own way.  This perennial root crop was grown and eaten across most of Europe for centuries prior to the Spanish conquest of South America.  After this time potatoes largely replaced skirret for a number of reasons.

Skirret is a perennial vegetable which, unlike many other perennial vegetables, also freely sets viable seed each year.  Most people who grow skirret reproduce it by breaking the plant into many smaller plants after harvest and replanting them.  Similar to yacon, the part you eat of skirret is different to the part you plant so you can increase the number of plants each year easily while still being able to enjoy the full harvest.

Seed grown skirret displays a lot of genetic diversity, I assume this is because no real breeding work has ever been done on it and it is mostly propagated by division rather than seeds.  Serious breeding of vegetables often results in highly inbred strains which contain all the desired traits but have little to no genetic diversity.  Sometimes this deliberate selection goes a little too far and the plants become highly susceptible to inbreeding depression (such as has happened to carrots and corn), other times it does not appear to bother the plants too much (such as tomatoes or beans).
The same skirret seedlings getting larger

What does skirret taste like

I am bad at trying to describe what things taste like and it has been a while since I last ate skirret but I will give it a go.  Raw skirret tastes kind of like carrot or parsnip or when cooked a little like sweet potato or potato, but skirret is sweeter than any of them.  That is probably not a great description as carrot and potato taste nothing alike.  Many people use skirret in the same dishes that potato, sweet potato, parsnip or carrot would be used.  Skirret is by far the most delicious roast vegetable I have ever eaten.

Skirret also used to be used for deserts and the like, but I am not exactly sure how/what they do with it in these meals.  As mentioned earlier, most of Europe grew and ate skirret until the potato came along so it has a long history behind it as a food plant.

Skirret contains reasonably high levels of sugars and tastes rather sweet.  When the Germans were searching for alternative plants to sugar cane they reported that skirret ranked below the white 'sugar beet' but above red beetroot.  Some of the common names for skirret translate into things like sweet root, water parsnip and sweet water root.  From these names you get the impression that skirret is sweet and likes to grow near water.
At this point I perhaps should have re-potted the plants separately

You can see the plant in the middle is already starting to divide

Problems with skirret and how to overcome them

Skirret can have thin roots, these can be a pain to prepare for a meal.  The roots are always long and there are always copious amounts of them, but if they are too fiddly to prepare no one will bother to grow or eat this remarkable plant.

Skirret can have woody cores to the roots.  Some people do not mind this, they cook the skirret and strip the roots with their teeth and discard the core.  I can't be bothered doing this and wont eat a vegetable which requires this kind of treatment.  First year plants grown from seed tend to have the woody core, as they age the core gets smaller or apparently even disappears in improved strains.  Lots of water seems to help prevent any woodyness at all.  Considering that this plant grows in marshes in the wild it makes sense that soil moisture would be beneficial.

Skirret loves cooler weather, I don't think it matters how cold it gets the skirret is never bothered.  It goes dormant over winter and is dug/harvested/divided during that time.  It does not love the heat.  As I currently live in an arid climate, lots of heat and very little water, growing skirret takes a bit of work.  Growing in part shade, or in a styrofoam box to help insulate the soil can help this plant to grow in less than ideal climates.  I have it growing in a pot which I can submerge in water on hot windy days.

Skirret is a plant that would benefit from some serious breeding work.  Pretty much every problem it has should be simple enough to overcome if someone puts the time and resources into breeding improved skirret varieties.  I honestly think if someone was serious about breeding skirret that it would only take 3 or 4 years to turn skirret from its current form into something truly remarkable.  If you ever do this breeding and grow improved varieties of skirret let me know as I would love to buy your plants or seeds.
Strong and healthy skirret

Everything looks good

Breeding potential of skirret

One of the great things about skirret is how happily it sets seed each year and it produces many seeds even if only one plant is growing.  Being in the Apiaceae family they produce copious amounts of seed if allowed, similar to a carrot, but in skirret the seed seems to display a lot of genetic diversity even if obtained from a single plant.

Most people who grow skirret do not grow from seed, instead they find a plant and do not let it flower so that all the energy is put into root development.  I think this is a mistake as it is not difficult to find a nice skirret plant, divide it and let one of the divisions go to seed so that you can continuously improve your stock.  Leaving a single plant in your patch to flower is not that great an imposition.  While letting several plants flower would be best, a single plant flowering and setting seed would still give a crop of diverse seedlings from which to cull and only keep the best ones.  The flowers attract a lot of beneficial insects so leaving a single plant in the back corner to flower is of benefit to the rest of your vegetables.

Skirret grows many edible roots which are nice and long, so there are no issues with root length or number, the problem comes from them being too thin and often having a woody core.  It should be possible to breed for superior varieties with fatter and less woody roots.  First year plants are more likely to have woody cores and plants that do not get enough moisture will also have a woody core so selecting for lack of fiber can be a bit tricky.  That being said, many people who have selected for improved plants overseas only do so for about 2 generations and then have plants that they are happy with.

I do wonder if skirret was grown using aquaponics or wicking bed if the woody core issue would be completely resolved due to constant access to water.  If this were to be the case then skirret breeding could focus on fatter roots, having one single focus should mean that improvements are made a lot faster as culling can be more harsh.

One of the issues we have in Australia is that so few people grow skirret that we probably have a bit of a genetic bottleneck.  Hopefully the natural genetic diversity on this plant will ensure that we can still select for improved varieties and make ground reasonably fast.  I would love someone to take on skirret and breed some improved varieties, if the woody core could be bred out of skirret there is no reason that people would not grow it in backyards or even for market gardens.  As mentioned earlier I have never heard of anyone who dislikes skirret, improved varieties could make this crop more common once again.  Skirret does not always cope with summer in my climate so does not always flower (or necessarily even survive) so I probably wont do a lot of serious breeding with it.  That being said each year my skirret does flower I will save and plant seed from the best plants and cull the weaker plants.
Skirret plants with adult leaves

Where to get skirret in Australia

People who know a lot about rare vegetables often tell me that skirret is not in Australia, and due to problems importing the seed that we will never be able to grow skirret.  I don't know how to respond to them as I have grown skirret before and I am also currently growing skirret.
Skirret plants in a small pot

I sell skirret plants over winter on my for sale page.  It is difficult to find skirret plants for sale in Austraia.  I also save seed from my best skirret plants each year to sell on my for sale page.  Each year my plants are getting better as I cull any under performers and only breed from the best.

At some stage I will include some growing notes on skirret.  If you have never tried skirret I think you should get some and grow it. 


  1. Hi Damo

    I posted this comment a week or so ago but it didn't appear so not sure if it worked or not.

    I am interested in growing skirret and have tried germinating seed from 2 Australian sources - Cornucopia Seeds and Rangeview Seeds. However no luck getting the seed to germinate thus far. Do you know if there are any tricks? Like you I am in an arid environment, in the warm season at least.

    Interesting comments on genetic diversity, but I wonder if the reason tomatoes and beans are more resilient to inbreeding depression is because they are naturally inbreeding plants as they are self pollinating and therefore don't cross very often - whereas corn and carrots have evolved to require crossing, to a greater or lesser extent. I suspect this is just different genetic strategies as much as influence by breeding?


    1. Hi Hughbert, sorry I didn't see the other comment. I am not sure what happened.

      Skirret seed seems to have reasonably low germination, which is ok if you save your own seed but not fantastic when you buy seed. I think it may be similar to parsley in that it requires decent water and a reasonable amount of time before it will germinate. I don't know if the seed needs to be fresh, I have read that they can be stored for 10 years but don't know how accurate that is. I have also heard that topdressing with rabbit manure or guinea pig manure helps increase germination rates, again I don't know if this is true or not. My plants are currently flowering, I hope to get some good seed from them.

      You may well be right about the outcrossing vegetables being more prone to inbreeding depression. Pumpkins, squash etc are probably the exception to this. They tend not to self pollinate without intervention, yet they can be inbred until the cows come home and display no noticeable effects of inbreeding depression. It is all very interesting.

  2. As someone who lives in an apartment in Melbourne, how deep does the pot have to be if I wanted to grow this on my balcony?

    1. Hi Leo,

      the pot in the photo above that I grew them in is only about 20cm deep, I think deeper would be better if possible but they certainly can grow in such a small pot. When the frost comes I will dig them up and take some pictures of the roots so you can see how they went.

      I also had 5 plants in that one small pot, one plant per pot is far better as competition makes the roots much thinner. Thick roots are easier to eat so I had planned on separating them into individual pots and growing some in the garden but they grew too fast and I decided to let them go for this year.

      Even crowded in that small pot they have all flowered and I have started to collect their seeds. By the looks of it they have all divided and in winter I should be able to split them into many plants. I will probably only keep the divisions from the best plants and kill off the rest.

  3. I wrote a short post and included a bunch of pictures of the skirret harvest
    It was not too bad all things considered. I forgot how much I like the taste of skirret, I wish I could buy it from the shops instead of having to grow it all myself. It is easy to see why it was so popular back in the old days.

  4. Great to find your blog. I have found that the easiest way to germinate skirret is by soaking for several hours than applying Deno's baggie method of germination in the fridge. Really fresh seed works best (typical for Apiaceae)

  5. Skirret develops small rooted plantlets next to the main stem. These can be separated and planted since they already have their own roots.

  6. This year we have had an excellent skirret harvest. I absolutely love roasted skirret and would eat it every day if I could.

    I have been culling pretty hard to try and improve my stock. This year none of my plants are producing a woody core, I am not sure if this is genetic (ie I have bred woody-ness out of them and they are now a form of "improved skirret") or if it was just the conditions this year.