Bill Grey wrote:
I'm sure I've read somewhere about people planting potatoes in large tubs.
Ican do this, but is it right that potatoes are planted at different layers
within the tub. If so is it because of different types of potatoes or for a
staggered crop.

I think it's more to utilise the space better! So each time you add earth
to cover up the plants as they come through, you just add a few more. Of
course, then you need to harvest them from the bottom up, which may not be
convenient. Or else wait till they're all ready before emptying the whole
thing.