Peter
I’m doing my first experiment with a potato tower this year and the Sarpo Miras (which I was provided evidence do well under tower conditions) and, with three levels of the tower now filled with compost, the seed potatoes have had to grow through the best part of 50cm (which is 20 inches) to break through. This they have just done in just under 6 weeks. I’ve added comfrey leaves at each stage of topping up, so hopefully the plant will have a nice nutrient source throughout the whole tower.
Does say that potatoes will grow successfully despite quite a deep planting…………..