The yield has been good from an Air-Pot potato tower that has been on the patio after an early start in the greenhouse. Rather than open it early and risk a lot of the tubers still being very small it has been left until well into July. Three Casablanca tubers planted in a pot have produced 3.5 kg which is more than I get per plant when grown in the ground. Three plants at the plot would generally produce 3 kg & take up an area about 1 metre square, whereas the potato tower has only a 42cm diameter. So with four potato towers fitting into one square metre small spaces can be very productive. The key to success has been plenty of water.