Potatoes are grown from both seed and tubers.

Plant breeders develop new varieties from true seed. These plants are in the diploid state. They then convert them to the tetraploid state by application of colchicine. After conversion they are only replicated via tubers.

The first generation is completed in the laboratory by cell culture. This ensures the starting point is free from diseases. Then they go to small sterilized plots where a few potatoes become more. This process repeats for several years increasing in quantity until the first pre-commercial potatoes are grown. During this time all fields are carefully inspected for diseases and contaminated productions are sold for consomption.

The potatoes are finally sent out to growers for commercial production. That's where they pick up all the lovely diseases and then are sent to the store.