companion planting: oca and tree collards (couve galega)?

southern England, Zone 9

I've converted some of what remained of my lawn to a vegetable bed over the winter. It gets decent sun and the soil is fertile. I'd like to get some good brassica production going (in the form of tree collards, aka couve galega / walking stick kale) and also to experiment with oca (a tuber from the Andes).
Will these two get on well together? I expect the collards will grow up high enough not to compete for space with the oca. But what about guilds and symbiosis and stuff?

I also have a bunch of young sea beet (Beta vulgaris subsp. maritima) plants in pots, ready to plant out once the weather gets warmer.

Last year I planted a whole bunch of stuff sprinkled at random. It looked great, but we didn't know what we were looking it (and whether it was ready to pick yet) so we ended up not eating a lot of it, mainly out of ignorance. I'm trying to be a bit more systematic this year.

Regards,
Paul

oca:
http://downtheplot.com/oca.php
http://www.pfaf.org/user/plant.aspx?LatinName=Oxalis+tuberosa

tree collards (aka couve galega / walking stick kale):
http://en.wikipedia.org/wiki/Collard_greens

lots of interesting and well-designed experiments with oca here:
http://oca-testbed.blogspot.co.uk/p/list-of-oca-trials.html

Digging the oca might be hard on your companion brassicas, but otherwise they'll get along just fine. I've grown oca with summer-harvested cabbages in order to maximize use of the bed before the oca fills in.

I heard you can increase the yield of oca by laying extra soil over the plants like you would for potatos. Havent tried this yet as I have only grown them in one season so far. So I don't know if you want to factor that in that when choosing the plant to grow with it. I have found tomatos really benefit from being buried deep in the soil so the two together could work really well with this approach.

Bill Dubiya wrote:Digging the oca might be hard on your companion brassicas, but otherwise they'll get along just fine. I've grown oca with summer-harvested cabbages in order to maximize use of the bed before the oca fills in.

Good point Bill - the oca will of course need to be dug up yearly. All my other stuff is no-dig. I will think harder