Oca Harvest? Wait for It, Wait for It...

These are my main 'eating crop' of Oca...

It's more than two weeks since frost killed off the top growth, and received wisdom says now is the best time to harvest for maximum yield.
They certainly look as if they've completely snuffed it — until, that is, the top layer of dead foliage is pulled back...

The stems underneath are still green and succulent.
And below ground, roots and subterranean stems are also alive and well, continuing to build tubers...

An interesting approach would be to try to enhance this self-protecting effect by using closer plant spacing. The resulting denser foliage might provide sacrificial protection against significant frost in much the same way as a covering of horticultural fleece.
Using raised beds, earthing up, and planting under suitable taller crops are also cultural methods that may give partial frost protection.

It's a gamble to wait too long, as I found to my cost in 2009, but the weather has been mild and as a result vermin have not been digging up the tubers much. The ten-day forecast shows no imminent frost that would spoil tubers close to the surface, so on balance, I think it's worth waiting to give those tubers the maximum time to bulk up.