Jun, Jul, Aug
Fill a potato bag or large pot (at least 40cm wide) with multi-purpose compost until it's two thirds full.
Lightly firm the compost, then set three seed potato tubers on the surface, 20-30cm apart. Add more compost to just cover the tubers.
Water well to soak the compost, then allow to drain, then place the container in a well-lit porch or greenhouse to start sprouting. When shoots appear, add a further layer of compost to cover them. Keep repeating this until the bag or pot is full.