Yacon — Storing and Dividing Propagation Caudices

Yacon propagules (or caudices) are easily bought these days, and most new yacon growers will quite rightly be expecting to save their own replanting material for future years. Certainly, that's what I confidently planned when I first grew the crop, but in fact I found out that it's quite easy to lose yacon caudices during winter if they are poorly stored.

The two killers are frost, and rot caused by cold wet conditions. Err, then there's desiccation if they dry out. Oh, and not forgetting mice.
So, simple enough you'd think, but finding a successful storage method has taken me a few years, and resulted in a few failures along the way.
I've tried storing them in plastic crates of damp compost in a greenhouse (one time frost got in, another year 'sweating' caused rotting).
I've tried storing them in cardboard boxes in an unheated room in the house (some dried out, while some sprouted far too early, and were then difficult to keep alive until planting out time)
Some growers claim success leaving them in the ground, but this can't be totally reliable, and would only work in favourable climates. The climate here is decidedly unfavourable.

In practice, the temperature criterium is fairly simple to control; I've settled on storing in an unheated brick-built shed (with the proviso that I may need to temporarily rescue them during times of penetrating frost).
Maintaining ideal moisture levels is not so easy, but my experiences have led to this method:-

When lifting crowns in autumn, I remove most of the spindle tubers for eating, but leave a few of the small ones attached. These (I assume) provide the crown with a reserve of moisture. Do not separate the caudices for storage — leave them attached to the crown, where they will be able to draw on moisture from the spindle tubers.
I brush off as much of the attached soil as is practical (if it is wet), and cut off the stumps of the stems as these often seem to be the starting point for rot during storage.
If the crowns have been lifted in wet conditions, I would leave them under cover for a day or two to dry off.
I then place the crowns in lidded buckets (the lids are perforated to avoid condensation) surrounded by a mixture of almost dry spent compost and very coarse sawdust. Any open and slightly damp medium will do, the important point is that it should not be too moist.
I then hang the buckets from rafters to exclude mice.

In March, I start checking the crowns every week, until I notice signs of growth...

This is a good time to divide the caudices and pot them up; small live buds confirm which caudices as viable. Any larger, and they will almost certainly be damaged during the violent dividing process.

I prepare by gently brushing away the storage medium to reveal the caudices, being careful not to harm any shoots ...

Then I start by trying to break the crown in half on any obvious line of weakness, though often a knife is needed for this first division. Thereafter it is usually possible to forcibly snap the caudices apart along their natural divisions. Be warned; this is not a job for a little old lady with arthritic fingers, or at least not unless she trains regularly by tearing telephone directories in half.

Each crown should provide between 5 and 15 propagules. Larger caudices can be further divided as long as each piece has at least one viable bud, but I prefer to leave them whole to make really strong plants.

Check each propagule for local rotting. Either discard, or trim back to healthy material for a fair chance of survival.
Pot immediately, and keep in a greenhouse, perhaps potting on again, before planting outside in May.

I've noticed that poorer, smaller plants, often provide more propagation material than larger ones. Based on that, and the fact that I got about 15 propagules from each of my plants, you should be able to work out how bad my crop was last year!

Yacon 'Fiorella' Goes to Market

For the last couple of years I've been lucky enough to obtain pre-release samples of "Fiorella", a recently bred fast-maturing variety of yacon from Paul at Yakon.co.uk
It's the variety that I've used in the 'All-tuber-mound', and 'Not the Three Sisters' planting schemes, and such is the superiority of Fiorella that I've now abandoned the white variety that I grew previously.

Here are a few of the edible tubers...

... and a shot of a typical root crown...

If your garden is prone to early frost, this variety could still work for you; it's said to be able to crop in 160 days. Certainly I've seen it tuberise by early September.

And it makes a very handsome border plant...

Anyway, the good news is that Paul has multiplied up his stock to the point that he can now make propagules available for sale. And if you just want the edible tubers, he sells those too.

This link will take you directly to the on-line ordering:
http://www.yakon.co.uk/shop.php
(not to be confused with yacon.co.uk which is a yacon syrup importer).

November is Tuber Time

Most conventional vegetable crops are on the wane by now, but the short days mean only one thing for Oca...

...make tubers, and make 'em fast! These stem-borne Oca tubers are getting noticeably bigger every day, and I've no doubt that those underground are similarly ascendant.  In fact, in places I can see the soil surface starting to heave upwards from the pressure of the swelling crop.

A hands-and-knees survey of the plot discovers plenty more underground action. This is the Ulluco doing its best to tuberise...

...and doing better than last year, when they were already frosted by now.

Chinese artichokes tubers are also bulking up. These are from the plants used as ground cover under climbing beans in the 'root crops as ground cover trial'.

And scraping around the base of a Yacon in the 'Not the Three Sisters' bed reveals sizable storage tubers.

All this bodes well for bumper crops. But of course, a frost could easily put a damper on that.

Unfortunately someone else has noticed all this underground fodder. This is a large excavation on one side of the 'All-Tuber Polyculture Mound'...

Oca, Chi-chokes, and bits of Yacon are scattered around. Rats could be the culprits, although a lot of the uncovered tubers have not been eaten. Then again maybe it's a fox. Anyway, the damage has put a halt to a lot of the plants in the mound.

Grrrrr!

Not the Three Sisters...

... not the traditional corn/climbing beans/squash polyculture, but a wilder and woolier version with slightly more obstreperous contenders. The Three Hooligans might be a more accurate name for what I have in mind.

Infant hooligans on planting out day (25th May)

'Hooligan 1' is Yacon,  Fiorella,  a Czech-bred quick maturing variety which I grew last year. I can confirm that it does indeed get a move on, and makes tubers long before standard Yacon. Each plant is liable to reach 8ft high by 9ft wide by the end of the season, and produce 10 to 15 pounds of edible tubers.

'Hooligan 2' is the Hog Peanut or Talet (Amphicarpaea bracteata). I don't have any previous experience of growing this, but it's reputation as a rampant reprobate proceeds it. I'm looking forward to trying the beans which form below ground. Thanks to Rhizowen for the seed, who was also thoughtful enough to provide the required specific inoculant to permit nitrogen fixing on the plant's roots.

'Hooligan 3' is admittedly a corn, as in The Three Sisters system, but this is Hopi Blue — a robust and highly variable variety, displaying diverse foliage colour, number of tillers, and ultimate height. It's usually described as growing to about 2 m but I think that must be in its arid homeland, as I have experience of it growing to more like 3m. Almost certainly there are different strains, which also might explain this difference.

But for a successful polyculture, it's as much about how you plant as what you plant. Here's a view showing the planting layout...

That's a 5 ft wide bed. Hopi Blue are more widely spaced than usual to admit light to the Yacon which are planted on the centre of the bed at 4 ft spacing. Hog peanuts are between the Yacon, and should climb to the light. You'll also notice a couple of rows of onions in there. They were planted back in March and could be a mistake, but they were a bargain and you never know, if they get a move on they could form an extra output.

A couple of weeks later the plants have settled in...

9/6/11

... and are still well-behaved, but for how long?

10/7/11

27/9/11 Corn ripening. Flowers on the yacon are a sure sign that tubers are forming below ground. And...

... the hog peanuts are producing their tiny delicate flowers.


16/10/11. The corn is harvested...

...and the corn plants removed. The yacon are about 8ft high and steadily flowering.

More updates later.

The All-Tuber Polyculture Mound, Part 2 ... Room for One More

A previous post showed how last year I used mound culture to grow a mixed tuber crop (Yacon, Oca, and Chinese artichokes) with the minimum of labour input.

Here's what's left of the mound... 

...untouched since last December when it was torn open to yield over 20 lb of harvest.  As I anticipated, there are plenty of volunteer Oca and Chinese artichokes appearing amongst the annual weeds this year, so I only need to add a Yacon to restore last year's successful system.

Less than five minutes after the previous photo...

... and the weeds are blotted out by a heavy covering of garden compost, and a pot-started Yacon is added to the top of the heap.

This much compost might seem like an extravagance, until one thinks back to the amount of biomass which was removed at harvest; here's the near hernia-inducing Yacon root as a reminder...

I'm also adding a fourth member to the polyculture. The Hog Peanut, or Talet (Amphicarpaea bracteata) is not a true tuber-crop, so stretches the concept slightly,  but will clamber and twine amongst the Yacon, potentially fix nitrogen, and hopefully add to the overall interest and subterranean yield of the mound with its wacky underground beans.

It's another self-propagator by all reports, so like the Oca and Chinese artichokes, it should be back every year...

...whether I like it or not.

Update photo, 1st August...  ...five foot high an' risin'.

Early Frost Carnage

Drat the BBC weather forecast!
4ºC was the forecasted minimum last night.  I believed them, but they got it wrong. The Oca bed looks pretty well devastated.

Yacon leaves are blackened...

...or at least the outermost ones. Those lower down seem to have survived damage, and I think the plants will recover.










This bed of Ulluco has been flattened too.

The only Andean to be unaffected is the Mashua, which is nonchalantly preparing to flower.

This is a freakily early frost for this area, and the situation is all the more annoying because I have rolls of mesh ready-and-waiting to give protection.

At first sight all seemed lost. But when I carefully lifted up some of the slaughtered Oca foliage, the optimist in me could see less-damaged stems underneath. I think they may live. Fingers crossed.
More checking revealed that the Oca in the 'all-tuber polyculture mound' have been protected, albeit sacrificially, by the yacon foliage. Free-range Oca on 'the other plot' are also alive and well, protected by their close polyculture competitor/companions.

This scare got me thinking. If it had been one degree colder, and all the Oca were killed this early in the year, they probably would not tuberise, and I'd be left with no seed tubers for next year. If the cold snap were to be geographically widespread, it might be very hard to find replacements. Does anyone keep Oca tubers dormant in cool-storage as an insurance policy against this sort of situation?

Not me, but maybe I should.

High Summer Miscellanea

A few things of interest that caught my eye while patrolling the plot the other day:

Tomato, De Barao Black (thanks Toad) with Oca growing at its feet. It's my first year with this variety, and it's turning out to be very productive - the canes are buckling under the load. The taste is slightly lacking in acidity, but it's good for cooking. I'll be saving seed and probably adding it to my 'grow every year' list.

That's Tigerella (also known as Mr Stripey) with Oca, as usual, providing ground cover. I've already demonstrated that tomatoes and Oca grow well as a bi-crop, and it's working just as well for me again this year.

The first of this year's Yacon flowers with a hoverfly getting stuck in. I'll be watching for seed setting, but like Oca, this is another awkward outbreeding blighter when it comes to pollination - this time because male flowers don't appear until after the female flowers, and even then, seed set is said to be poor.

A domestic bee and a bumblebee doing their thing on a globe artichoke. The plot is literally buzzing with pollinators this Summer. This is partly because we have beekeeping on the site now, but also the increased use of organic methods by plot-holders seems to have boosted the general insect population. This is all good news, especially for those of us aiming to collect seed from difficult-to-pollinate crops like Oca or Yacon.

This is Ulluco, which I'm growing for the first time this year. Having now seen its growth habit, it seems another strong candidate for ground-cover in a vegetable polyculture. It's lower-growing than Oca, and fills out as ground cover a bit earlier in the season. I could see it working well with leeks, corn, chili-peppers, tall peas, tomatoes...
But first, I need to obtain tubers from this year's crop, which is by no means guaranteed from all accounts.
Update: Harvest results here.

Other gardeners have squashes growing out of their compost heaps ...
Hats off to Oca, a resilient survivor - last year's dross tubers have sent stems struggling through the 3mm wide aeration holes of this plastic compost bin despite being buried under two feet of mouldering vegetable peelings.

The All-Tuber Polyculture Mound

In a quiet corner of 'my other plot' I'm trying another cultural method - a four foot wide mound with three different tuber crops grown closely together. I'm aiming for a low-maintenance easily-harvested dense ruck of tuberous productivity.

Unlike standard polycultures, a clear requirement for an all-tuber polyculture is that the crops involved should mature, and be harvested all at the same time, otherwise lifting one will disturb the roots of those remaining.
Oca, Yacon, and Chinese Artichokes together satisfy this criterion quite well, all normally being harvested after their top growth has been killed by frost.

I started in Spring by clearing the area of the previous Jerusalem artichoke crop (yeah, right!), and digging in a barrow-load of rough compost. This was more to improve water retention and aid soil friability (and hence make harvesting easier) than it was to boost fertility. On top of the mound goes one of my prized new variety purple Yacon, purportedly quick-maturing, but so far untried by me. It is certainly much more vigorous than my other 'standard' Yacon variety. Around this goes Oca, then on the outside edge are the Chinese Artichokes.

This little experiment could easily be scaled up to an informal linear raised bed (or 'lazy bed') if one wanted. It could even work on a commercial scale if suitable harvesting machinery was available.

With all the incorporated compost, thorough deep cultivation, and dense weed-suppressing foliage, this is also ideal as a once-and-for-all soil improvement method before turning ground over to no-dig culture.

Drought is the problem this season. All three crops are showing stress, but it will still be interesting to see what quantity of tubers can be got from this single square metre of ground.

Update 31/8/10

The drought has given way to a couple of weeks of pleasant showery weather. The soil moisture, no doubt helped by all that compost in the mound, has caused the Yacon to double in size. It is now seven foot wide and tall, topped with a lanky bouquet of flowers.
It is even suppressing a couple of late-breaking jerusalem artichoke volunteers, and I now fear for the productivity of the Oca and Chinese artichokes.
I either need a smaller Yacon, or a larger mound!

Update 1/11/10

The first air frost on 21/10 burned back the yacon foliage, but has not completely killed it. Under its protective canopy, the Oca plants have escaped damage, unlike those planted on open beds nearby.
A few days before the frost, I noted the yacon had grown to have a spread of nine feet!

Update 12/12/10
There has been freezing weather for a couple of weeks, and the plants are showing no sign of life. It's a dry day, so a good opportunity to exhume the contents of the mound.

First up is the Yacon. It's a big one! The Health & Safety Executive would have me use a hoist for this job, but after a bit of grunting I manage to get the crown in to a wheelbarrow solely by manual handling methods.

After washing, the useable tubers weigh in at 18 lb (8.2 kg), with another pound or two of small or damaged ones.

Delving around nearer the edges of the mound reveals the 'also rans' – a moderate scattering of mostly undersized Oca and Chinese artichoke tubers.

About 1.5 kg in total – which is as much as I can expect given that the plants have been camped under dense Yacon foliage for most of the growing  season.

CONCLUSIONS
This growing method was successful in terms of yield and low-labour, despite an unusually early frost. Next year it will be even easier; it will only be necessary to plant the Yacon, as there should be ample volunteer Oca and Chinese artichokes.

The imbalance in yield between the three crop species was caused by misjudging the vigour and final size of the particular variety of Yacon chosen. I mistakenly assumed it would be similar to the 'standard' Yacon that I have grown previously, and as a result the Oca and particularly the Chinese artichokes suffered from lack of light. However, a variety being too successful is a good fault, as they say.

It is an interesting and potentialy useful observation that the Oca were protected from the first frost by the Yacon foliage. Yacon, not being reliant on day length, can tuberise early, before sacrificially protecting undergrowing tender crops which have yet to fully tuberise. The partial defoliation lets through more light to ground level, and as long as there is not a second frost, the lower crops benefit.

Yacon Doubletake

Okay, so this is not about Oca. I am growing yacon again this year to try as a bi-crop with Oca, and as I was watering yesterday, I noticed one yacon plant that was different:

On the left is a normal yacon, with two leaves at each leaf node. On the right - the strange plant, with three leaves on each node. The leaves on adjacent nodes are rotated by 60º relative to each other, so I believe that makes it a decussate whorled pattern.
The plant has grown from a propagule consisting of about three little tubers, and only one of these has produced the non-standard leaf pattern, so it looks like the parent plant was normal, and the mutation has occurred in the replant tuber.

The plant is the most vigorous of all that I have, and the stem in question is the most vigorous on the plant.

The root system is strong and healthy. Perhaps this will be a yacon with 50% extra.

Update 4/9/10. The stem is flowering now.

With side shoots reverting back to two leaves per node, it seems I'm not going to be able to perpetuate this variant. But I'll keep the replant tubers that form at its base this autumn, and check them when they re-grow, just in case...

Update 28/3/11. Saved tubers killed by heavy frost during the winter.