Potato plant distance?

Ok, if youve seen my other post you will know Ive just taken a plot on and am trying to work out my planting. Ive got a bed ready for my early spuds (They are out chitting in my shed). Now, my bed is 12' by 5' and was wondering how flexible the planting distances could be? Would I be pushing my luck to have four rows in this bed? It would mean each plant is 12' apart and also each row would be 12'? Am I cutting it a little too close? What if it was 2 rows of earlies and 2 rows of main crop? What do you think would be the best way to plant my spuds in a bed this size?

Thanks for bearing with a newbie!

Rich

I think you should be ok with that with the earlies. I tend to prefer smaller earlies so lift them a little bit earlier.