oca in pots

30L sounds a lot but then it is just half a bag of compost ... as the crop is in the roots, you don't want them cramped so I'd almost say 1 tuber but you might get away with 2 (3 might be stretching it)

I agree with BabyAnn, I would go for 3 max so they have plenty of room (mine were 2-3 ft tall last year, depending on where I had them, although they do 'flop' a bit). 

I have heavy clay soil and they were fine.  They seem to be fairly hardy once they get going, and having them in the ground was much easier as I just left them to it.  Just think potato (without the blight)...

I would  tend to agree with one or two, I have grown them for a few years. I mound them up now like potato's
You get a better yield  if you mound them up. It might be a good idea to experiment this year to see what works best in pots. They would be easier to harvest out of a pot than digging the little suckers up out of the ground. 

Thanks for all the replies,
I think I will do a couple of pots worth and build a raised bed for them as I have the space

Dmg