Tag Archives: oca

Winter harvests 2015

A very mild end to 2014 in Aberdeen meant that a lot of my root crops didn’t get harvested until the end of December and I am still digging some up now.

oca crop

The late frosts were ideal for the oca, which only starts to tuberise around October and therefore had a good long season. In a bad year here frosts can cut it down before it produces any tubers at all. As well as the ones I planted, I had a crop of volunteer oca coming up where I had them last year. Interestingly, they had the same yield as the planted, manured crop and bigger, better tubers. I suspect that this is down to the wider spacing and resulting larger individual plants. They were also less chewed-on by beasties in the soil, presumably due to the lack of compost. I’ll try to recreate these conditions with my deliberate crop this year. One surprise when I dug up my oca was that one tuber on one of the plants was almost white, compared to the pink/orange colour of the rest. I’m told that such colour sports are quite common in oca, and look forward to propagating my very own strain!

Roots, tubers and swollen stems form a pretty large part of my diet in winter. I counted twelve in last night’s stew, some from store, but mostly just dug up: turnip, sweet cicely, potato, oca, yacon, carrot, parsnip, salsify, Hamburg parsley, udo, Chinese artichoke and skirret. Such a variety gives a wonderful flavour even with the simplest of cooking methods. Two of the above perhaps count more as spices than as main ingredients: the sweet cicely and the udo. Sweet cicely root has a strong aniseed taste which is overpowering raw or in bulk, but adds a great flavour sliced thinly and sparingly into any dish. I dug up a mature sweet cicely of maybe four or five years’ growth this autumn, being as careful as I could not to break the root. It finally snapped off at about one inch in diameter. The part I dug out was over a metre long. It would have been interesting to have excavated the last section to find the total length, but I had reached the limit of my spade! Perhaps not surprisingly, this one root has met all my sweet cicely needs so far this winter. It has stored extremely well simply kept in a cool place (being far too large for my fridge).

sweet cicely root

Udo (Aralia cordata) root is similarly best used sparingly but at least it is easier to dig up. It has a similar taste to the spring stems, with some slightly harsher notes mixed in. The real gourmet food available from udo at this time of year is the underground stems that it puts out as runners to spread itself. Cooked briefly they have a melting texture and a taste very similar to the spring shoots.

There were a few other rooty experiments during 2014. Burdock (Arctium lappa) root cooked as kinpira gobo was utterly delicious, but I have had to restrain myself as I would like to grow most of my roots on for seed. I often have trouble getting bought burdock seed to germinate and my usual solution for that is to produce seed myself so that I know it is fresh. By contrast fennel roots were a disappointment. Fennel (Foeniculum vulgaris) self-seeds itself freely around my allotment and its roots are edible, so I had high hopes, but they turned out to be extremely bland and boring, with none of the flavour of the leaves or seeds. One breeding task I set myself this year is to see if I can get my very hardy and vigorous herb fennel to cross with the bulb-forming Florence fennel. They are just different selections of the same species so how hard can it be?


Skirret – Sium sisarumAnother root with lots of potential is skirret (Sium sisarum), another carrot relative. Instead of the traditional single root it produces a massive cluster. This makes peeling a job only for the seriously dedicated, so I always use them with the skins on, which fortunately is fine. They have a deliciously sweet, carroty taste and a nice floury texture after just a few minutes cooking. Cooked longer they will disintegrate entirely, which can be useful for flavouring soups or stews. A cluster like the one above will grow from a small division if it is given a rich, moist soil. I clearly didn’t give it quite enough moisture this year as my roots had a thin, woody core, which they develop in dry soil. This can be worked round by using the roots sliced thinly, but this year I have dug them a sunken bed next to the water butt and dug in plenty of leaf mould, as I feel that this is a crop really worth getting right.

Chinese artichokes (Stachys affinis) also did well. For anyone who hasn’t tried these before, they have a mild flavour and a nice crunch and look almost exactly like big, fat, white grubs, to the extent that I managed to kid my flatmate on for a good while that that was what was in the evening’s stew. I also tried rough bugleweed (Lycopus asper), which is similar to Chinese artichoke in many ways, but to my mind inferior in both taste and texture.

Two more tubers, both in the bean family: regular readers might remember my struggling hopniss (Apios americana) tuber, which every year manages to scrape together enough resources to yield exactly one tuber at the end of the season. This year’s warm conditions allowed it to produce an unprecedented six tubers. Needless to say, these are far too precious to consider eating: with such an abundance I’ll be able to try a few more ways of growing this fascinating plant before I finally admit that it is too cold for it here. That point may come a little sooner with talet (Amphicarpaea bracteata). Strictly speaking talet doesn’t produce tubers but beans growing on underground stems which serve the same function. Since growing underground poses certain challenges to fertilisation, the beans produced in this way are asexually produced and, in good conditions, the plants also bear an above-ground crop of seeds in the usual way. Unfortunately, in my case I ended up with vastly less reproductive material than I started with. I began with a good source of seeds, sourced from the northern end of talet’s range in Nova Scotia, and a handful of tuber-beans. Although I felt rather like Jack planting these, magic beanstalks did not result. In a wide range of planting sites, including a pot in my balcony, my allotment and another site further inland which experiences slightly hotter summer conditions, the plants grew very weakly and at the end of the season careful digging managed to produce only two underground beans. I’ll do what I can with these next year, but more in hope than anticipation.

Moving above ground, a few hardy plants are still giving me fresh veg straight from the garden despite the sub-zero temperatures. Daubenton’s (perennial) and Pentland brig (biennial) kale are still performing well. Nine-star perennial broccoli also produces tender and sweet leaves that are excellent as a winter kale, despite being a cauliflower than thinks it’s a broccoli! Leeks (Allium ampeloprasum var. porrum) are for me the undisputed king of the Scottish winter garden. I only grow winter varieties such as Bandit and Musselburgh, the latter being a traditional variety that has never been beaten. There are so many other alliums available in the perennial garden for the rest of the year that there is hardly any need for another, but in the depths of winter leeks really come into their own, laughing at freezing temperatures and even continuing to put on a little growth, with a flavour that for me beats even that of cultivated onion (Allium cepa). Garlic (Allium sativum), elephant garlic (Allium ampeloprasum var. ampeloprasum) and Babington leek (Allium ampeloprasum var. babingtonii) are all putting up shoots that could be cut and harvested, although apart from some garlicky-tasting leaves from the elephant garlic I mostly leave these for spring and summer harvest.

Having read Stephen Barstow’s book, I plan to do a lot more with indoor sprouting of seeds and forcing of roots for greens next winter. Since Stephen managed a salad with twenty different plants this week despite the 24-hour darkness of a Norwegian winter outside, he clearly knows what he is talking about! As an indication of what can be done, a salsify root left in the fridge while I was away over Christmas took matters into its own hands and produced a large head of succulent, white leaves. Finally, despite the sub-zero temperatures outside, one plant is already beginning to sprout. The leaves of alexanders (Smyrnium olusatrum), picked just as they emerge and slowly fried in butter, have a delicious taste that gives a promise of a new season to come.

Back to my roots (and tubers)

One of this year’s experiments in the allotment has been to try to get more starchy roots, tubers and bulbs into the forest garden. I haven’t had any straightforward, unmixed successes, but definitely some interesting leads that I want to follow up.

One fruitful (rootful?) source of edible roots is the Apiaceae or carrot family, home to the carrot and parsnip amongst familiar roots, as well as a large number of the plants that we use as herbs and spices (cumin, celery leaf, coriander, parsley, fennel, dill…). In particular, I was interested to try the native members of this family that have a culinary reputation: sweet cicely (Myrrhis odorata) and native hogweed (Heracleum sphondylium). Both have other edible parts (with some care in preparation required for the hogweed) but that’s a topic for another post. This time I wanted to get to the root of the matter.

I have tried sweet cicely root before. Like the rest of the plant, it has a strong aniseed taste, although the flavour moderates with cooking. Even so, it is a root to use sparingly in dishes with milder ingredients rather than to tuck into a plateful of. Mature sweet cicely roots are truly massive – and so deep that they are next to impossible to dig out whole. Unfortunately they are also not very nice: I only find the first year’s roots palatable, so I think that the answer is to have a few favoured plants as perennials for shoots, leaves and seeds and grow the roots as an annual crop.

I sowed a few rows in a couple of different sites with different seed sources, intending to select for the largest and straightest roots. The results were interesting. Site one was in open vegetable beds. The roots were a decent size but almost all quite heavily branched. Site two was quite shaded and yielded smaller but much straighter roots. I’ll have to do some experiments to find out whether this was genetic or due to the shade. Anyway, super-cicely is not on the horizon quite yet, but I’ll keep working on it.

sweet cicely roots

sweet cicely roots

The situation with hogweed is much simpler to report. The boiled roots were revolting. Yuk. I think I’ll be leaving them to the hogs from now on – although it does occur to me that I didn’t get to try first-year roots…

Other carrot-family roots include Hamburg parsley, which I’ll write about soon, and skirret (Sium sisarum), a perennial which bears a multitude of sweet, pleasant-tasting roots. Harvesting it involves digging it up, taking off some of the roots and putting the rest back in the ground. Turnip-rooted chervil (Chaerophyllum bulbosum) is a biennial with very pleasant-tasting but rather small roots. There is some evidence that strains with larger roots existed in the past so I’ve been growing the biggest of mine on for seed.


Another two candidates were South American crops that I have tried before years ago and which I decided to have another go at: yacon and oca. Oca (Oxalis tuberosa) is a tuber-producing relative of wood-sorrel, so the tubers have that lemony oxalic acid taste when they are fresh, but fortunately if you leave them in the light for a while it goes away. The big difficulty with growing oca at this latitude is that they only start to tuberise at around the autumnal equinox, by which time the frosts might be only a few weeks away. This year there were no hard frosts until November and I decided to try a little experiment. The plants had grown luxuriantly and I felt that they still had a lot to put into tuberisation if they weren’t completely killed by the frosts. I dug up one plant, covered two in horticultural fleece and buried a fourth under a thick layer of leaves. A couple of days ago I dug up the protected plants to compare yields. They were:

325g first plant
400g each for fleece-covered plants
550g mulch-covered plant

I imagine that a statistician would tsk at the size of my trial, but the results do suggest that covering the plants was worthwhile. The leaf mulch was more effective at insulating the tops than the fleece as well as being cheaper. Overall though, the yields are still rather disappointing for the space taken up. I don’t think that oca will really fulfil its promise in Scotland until someone finds a strain that starts to tuberise immediately. It isn’t too much to hope for as potato suffered the same problem originally.

Oca tubers

Oca tubers

Yacon (Smallanthus sonchifolius) is also frost-sensitive but had managed to put on a more impressive set of tubers than the oca by the time the frost hit. Like the related dahlia (also edible but not very nice), yacon crowns have to be brought inside to overwinter. It has two kinds of tuber: vegetative ones which will grown the next year’s plants and storage tubers which you can pick off and eat. The great drawback of yacon is that, like so many otherwise-promising plants in the daisy family (Jerusalem artichoke/sunroot, chicory, dahlia, elecampane, scorzonera), its roots are packed full of inulin, a sugar which can’t be digested by humans but which our gut microbes happily use, creating rather a lot of gas in the process… The culinary virtue of yacon tubers is that they keep their crunch even when cooked, so a little bit in a meal is great for adding texture, but I wouldn’t want to try to live on them.

yacon tubers

yacon tubers

The pea family (Fabaceae) is better known for its seeds than its roots, but there is a small number of tuberous species and one fascinating plant called talet (Amphicarpaea bracteata) that has adapted its seeds to work as tubers. This year I tried growing aardaker (Lathyrus tuberosus, also known as the Fyfield pea or Dutch mice: the Dutch name means earth-acorn) and cairmeal (Lathyrus linifolius, also known as bitter vetch or heath pea: the Gaelic name is pronounced like Carmel).

The aardaker gave a small crop of inch-long, tapering tubers that did indeed put me in mind of both mice and acorns. I would rather grow them on than lose any of them by eating them, but everything I have read about them suggests that they are delicious. The yield wasn’t exactly large, but it was produced in a very small space and, like all the peas, they have the added virtue of fixing nitrogen from the atmosphere, so I definitely think that this is one to keep an eye on.

Lathyrus tuberosus

Lathyrus tuberosus

By contrast, the cairmeal tubers were tiny. I couldn’t even take a photo that showed them properly. I won’t give up on it but might just abandon it for a couple of years and see how it gets on. There are advantages to cairmeal that make me want to keep trying: it is shade tolerant and has a long history of edible use in the Highlands.

Silverweed (Argentina anserina) is another plant that is reputed to have been used in the Highlands but has a bit of a problem in the yield department. I’ve had it in my lawn for years but decided long ago that its roots weren’t worth the effort of digging them up.

This year, I thought it would be interesting to take a closer look at the growth habit of the plant and transferred a few to pots of compost. They are strongly runnering so it can be very difficult to dig up a whole plant from the ground. In the autumn I shook off the compost and got a great view of the roots – with their swollen sections often at the end of the root but sometimes with the root carrying on beyond them. On the plus side, the roots taste great. I’m going to keep growing them in pots in order to (a) stop them invading the rest of my garden and (b) see if I can isolate individual strains and compare them.



Finally, some negative results. Two plants that I grow for their edible flowers, king’s spear (Ashphodeline lutea) and day lily (Hemerocalis lutea) are said to also have edible roots so in the autumn I dug up a few and tried them. Neither seemed worth it. The burdock (Arctium lappa) that I sowed produced next to nothing, as it usually does. I don’t quite understand this as burdock grows well in the wild here. I consoled myself with the thought that since they are in the daisy family they probably aren’t that much good anyway [UPDATE: I was wrong. See here]. My hopniss (Apios americana), another member of the pea family, did what it always does: it used all the resources in the one tuber that I planted to produce a total of one solitary tuber at the end of the year. I’m beginning to think that I could achieve the same result by pickling it rather than by planting it. It was a similar situation with the pleurisy root (Asclepias tuberosa). I’m experimenting with a few plants in this genus but mostly I think the climate is just a little too cold for them here. My attempt to grow Chinese artichoke (Stachys affinis) took rather a blow when the supplier sent me what turned out to be the related wild flower betony (Stachys officinalis) instead. Finally, my rampion (Campanula rapunculus), which is said to have long, fleshy, white roots, produced nothing but fibrous roots. From talking to others, this seems to be a common problem: has anyone out there ever grown rampion successfully?

rampion - where's my roots?

rampion – where’s my roots?

Other rooty posts: Chufa/tigernut; Wasabi, horseradish and friends; Self-seeded parsnips; Growing pignuts; Dog’s tooth violet
Next installment: Back to my roots (and tubers) – 2016