Potato seeds are harvested from potato fruits. The pollinated seeds are called "True Potato Seed" (TPS) to differentiate them from "seed potatoes" which are genetically identical clones of a tuber. I do not like growing a lot of clones in my garden because of the danger of total crop failure due to genetic uniformity. However potatoes are a crop that is easy to propagate by cloning, and during good times potato clones produce a lot of food.
I grow a combination of cloned potatoes and potato seedlings each growing season. By growing the clones, I am planting varieties that have grown well for me in the past. By growing true potato seeds, I am introducing genetic diversity into my potato patch, and adapting potatoes to my local conditions and way of doing things. Each year I select a few of the seedlings to grow as clones the following year. I aim for balance between the clones and the seedlings. I want to constantly refresh the genepool and search for new and better varieties while maintaining the varieties that have done well in the past.
As is typical with landrace gardening, lots of fun shapes, colors, and tastes show up among the offspring of true potato seeds.
Most potato varieties are unable to make fruits or produce seeds. I do not allow those varieties into my garden. If a potato plant does not make an abundance of fruit I do not replant it the next year. It seems important to me to only grow potatoes that can make lots of seeds so that I can plant the seeds to localize the population to my garden via survival of the fittest plant selection.
Potato seeds look and grow much like tomatoes, except that they are smaller. I grow them approximately the same way that I grow tomatoes. Due to the delicate nature of young stems, potato seedlings grow best in very bright light (direct sun or close to a grow light). I plant them outdoors after danger of frost is past. Potatoes may start forming tubers in the pots, so I recommend growing them in pots for no more than 8 weeks prior to transplanting. The delicate stems can benefit by transplanting a couple of times shortly after germination to bury the stems up to the first leaves.
To harvest potato seeds, I pick the berries which are like small green cherry tomatoes. I figure they are ripe when they get soft or turn slightly yellow. I often store them on the shelf for weeks or months after picking. To extract the seeds, I add one cup of berries to 6 cups of water and blend for 30 seconds in a blender on medium. The pulp floats and is discarded. The seeds sink and are collected and dried. Potato seeds remain viable for years and can be used to regenerate a crop even if every cloned tuber is lost. Potato seeds are less likely than clones to transmit diseases or pests to next year’s crop.
By growing genetically diverse plants from true (pollinated) potato seeds I am developing a locally-adapted potato population, and I am reducing the risk associated with growing only clones. This is part of the reason why I believe that landrace gardening is a path towards food security through common sense and traditional methods.
Next week I will write about saving landrace seeds.
Joseph Lofthouse grows vegetables in a cold mountain valley in Utah where he practices the art of landrace gardening in order to feed his community more effectively.