A couple of years ago I read a great book about one man’s life and death struggle … to grow potatoes. It turns out all you need to survive on Mars is potatoes, water, oxygen, and a supply of Disco music. In this post we’re going to help you bring out your inner Mark Watney as we take a look at growing potatoes.
“I don’t want to come off as arrogant here, but I’m the best botanist on the planet.” –Mark Watney, The Martian
What are Seed Potatoes?
The term "seed potato" can be a little misleading. Although potatoes do set seed, they do not grow true to seed. To get the variety of potato you want, you need to grow them vegetatively, meaning you re-plant a part of the actual potato. These pieces of potato are referred to as seed potatoes.
Selecting Seed Potatoes
Because potatoes are propagated vegetatively, any diseases from the prior year will be carried over. That's why it is so important to use disease free seed potatoes and that means certified seed potatoes, rather than supermarket potatoes. Certified seed potatoes are certified by the USDA Animal and Plant Health Inspection Service to be disease free. The process is similar to the phytosanitary certification process we go through at Bob’s Market when shipping plants to other countries or restricted parts of the US.
However, even certified potatoes can contract disease once planted, especially diseases that are not apparent in the seed stage like ring rot or fusarium wilt. Still, at least you have a bit of an edge, with some disease tolerance. Any potatoes that have soft spots, cracks or bruises or signs of rotting should be discarded. Start with the healthiest, strongest seed potatoes, to avoid problems and guarantee an good harvest.
So what exactly do you plant?
You do not need to plant a whole, intact potato. However, many choose to do that to increase your chances at successful propagation. Seed potatoes can be cut into pieces, as long as the pieces have at least 1 eye each. An "eye" is a bud that grows into a new plant. If you've ever kept your potatoes in the cabinet too long, you've probably seen them sprout.
If you choose to cut your seed potatoes, do this one to two days in advance so the cut end can callous over. This will help prevent rot when planted. Laying them out in a warm, dry location will help the callousing process.
Dig straight, shallow trenches, 2 to 3 feet apart, in prepared soil. Plant seed potatoes 12 to 16 inches apart and cover with about 6 inches of soil. When the shoots reach 10 to 12 inches tall, use a hoe or shovel to scoop soil from between rows and mound it against the plants, burying the stems halfway. Repeat as needed through the growing season to keep the tubers covered.