I just have two potatoes planted in an average size patio pot. I think it's 35cm wide and probably 40cm deep.
I looked up on YouTube how to plant potatoes in pots.
So, I put multi purpose compost a quarter full in pot, then put my two potatoes on top with the little growths facing upwards and then covered with more compost and watered it. Then I have to leave until I see leaves come through. Wait until 5 cm or so high and cover again with compost, not completely covering leaves. Keep going with this top up until reach the top. Let the leaves grow and keep watering. Then when it flowers I can feel and see how big the potatoes are!