According to the Idaho Potato Museum, the average American eats about 124 pounds of potatoes each year.
With taters consistently trending, it’s no surprise that many vegetable gardeners consider growing their own spuds. But how difficult is it to grow potatoes for those homemade fries, hash browns and casseroles?
Recently Amanda Gevens, chair of the University of Wisconsin-Madison’s Department of Plant Pathology, visited “The Larry Meiller Show” to talk about our love affair with the potato and how to get a successful potato harvest in your own garden.
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“The importance of this crop globally has just continued to increase,” Gevens said, noting that potatoes, along with rice, wheat and corn, are among the top staple food crops across the globe.
Growing potatoes 101
Seed potatoes are potatoes intended for planting to grow new crops, whereas regular potatoes are meant for eating.
When buying seed potatoes, Gevens suggested looking for potato tubers that are “dry, not soft, but firm. If anything is soft and squishy or wet looking, then use your nose. If it smells off, it may mean that you do have a soft rotting bacterium.”
According to Gevens, Wisconsin is prime real estate for potato growers:
- Potatoes do well in cooler weather. They need temperatures above 45 degrees at night and above 55 degrees during the day;
- They need more than six hours of daylight each day;
- They require slightly acidic soil with a pH between 5.8 and 6.5;
- Potatoes need good drainage and like fertile soil.
“You can grow potatoes in anything,” Gevens continued. “As long as you have good drainage and good depth.
She said when you plant seed potatoes:
- Make sure they’re 4 to 6 inches deep in the soil;
- Once the potato tubers begin to grow (which happens at the soil level), cover them with soil, hay, straw or another type of covering. If exposed to too much sunlight, the skin could turn green;
- Make sure there’s enough room for the plant to set its tubers. It needs about 12 to 18 inches.
Be aware that too much shade can also be problematic.
“Shading, particularly in potatoes, can often lead to more foliar disease. Keeping your plants out in the open where they receive more sun does help keep disease down with potatoes,” Gevens said.
In terms of when to plant, Gevens advised that some gardeners like to wait until May, even if April weather is conducive to growing potatoes.
“In fact, some even wait until June before planting potatoes to avoid things like Colorado potato beetles. I do think it’s best to actually wait a little bit and plant a little bit later,” she said.
Beware the potato scab
Potato growers need to be mindful about the common scab, a potato disease caused by the bacteria Streptomyces, a pathogen that accumulates on some seed potatoes.
“The disease is common to potato growers who hold seeds over and use them in the next planting cycle,” Gevens said.
For growers who discover scabs on their seed potatoes, Gevens recommends “starting over with a new potato seed, preferably bought from a garden center where potatoes sold as seed have been tested and certified.”
To avoid or limit common scab, Gevens said:
- Evenly water throughout the growing cycle;
- Don’t allow tubers to get too dry;
- Check the pH of your soil, which should be slightly acidic.
Harvesting and storing potatoes
As far as how long to store potatoes, Gevers said that it depends on the flavor that you want.
“If you harvest early, you’ll get a new potato, one that you can scratch the skin right off with your thumbnail. Those have a slightly different flavor, a little bit more earthy and more metallic. Those can’t be stored. If you leave them in the soil a bit longer the skin will set, and they’ll be much firmer. That changes the flavor and those can be stored a bit longer.”
If your potatoes are different sizes, that can be normal, Gevens said. But it could be worth checking to see if the potatoes have been watered or fertilized inconsistently.
“Making sure you’re providing them with adequate amounts of nutrients and water is important for them to produce more consistently,” Gevens said.
Potatoes, guaranteed
Gevens is currently the administrative director of the Wisconsin Seed Potato Certification Program, which was formed in 1913 to inspect and certify Wisconsin seed potatoes with a goal of providing Wisconsin farmers with a reliable source of healthy seed potatoes.
“We maintain potato tissue culture, plant hundreds of varieties of potatoes, and then we take those tissue culture platelets and grow small potato tubers in a greenhouse up in Rhinelander,” Dr. Gevens explained. “Those first generation potato tubers are sold to seed growers.”
“Then we have field inspections and harvest testing. Once we have enough data to determine that a potato plant is disease-free, certification is given and then those growers can sell their seed to commercial producers,” Gevens said. “That’s how we ensure the quality of the roughly 65,000 acres of potatoes harvested in Wisconsin each year.”
Popular potatoes in the Badger State
Perhaps not surprisingly, the most popular potato varieties in Wisconsin — and in the United States as a whole — are russet potatoes and russet varieties including norkotah and gold rush.
“Reds are still popular, but what’s gaining are mid-sized, creamer-size yellows or mixes where you get smaller potatoes that might be yellow, purple or red in a blend. Those types of smaller potatoes are gaining in popularity,” Gevens said. “Some of the reasoning is that they’re easier to prepare. We also have substantial commercial production for round white potatoes to make chips.”
Just as it is difficult to stop eating potato chips once you start, Gevens is confident that once gardeners start growing their own potatoes, they’ll be hooked.
