Dakota Gardener: Growing sweet potatoes in the North

Do you like sweet potatoes?

I love them. Sweet potatoes are a favorite food for Thanksgiving, and my kids love sweet potato fries.

Can we grow sweet potatoes in North Dakota?

It’s not easy.

Sweet potatoes are from the tropics. They need a long growing season, a lot of heat and moist soil.

That does not suit us well in North Dakota.

We have one of the shortest, coldest and driest growing seasons in the U.S. Many sweet potatoes harvested in North Dakota are scrawny and yields are low.

Don’t be discouraged. I’ve seen several families in our state grow bumper crops of high-quality sweet potatoes. Let me share with you some of their secrets.

Sweet potatoes are not grown from seed. They are grown from vine cuttings called slips. You can purchase slips online or at some garden centers.

If you buy slips, look for the earliest maturing variety you can find. Popular choices include Beauregard, Covington or Georgia Jets. Other varieties may not mature before frost.

Many successful gardeners in North Dakota grow their own slips. Slips purchased online suffer significant shock when they are dug and transported across the country. These slips will arrive at your home wilted and sometimes do not have any roots on them.

In comparison, slips grown at home have healthy root systems and suffer much less shock before being set in the garden.

It’s easy to grow your own slips. They can be grown in water or in soil. Homegrown slips are started now in mid-March.

Get a sweet potato from the grocery store, cut it in half, and place the cut ends in shallow trays of water. Change the water at least every few days.

Another option is to poke toothpicks in the middle of a sweet potato and suspend the potato in a glass of water so the bottom half of the root is submerged.

Slips also may be started in soil. Fill a tray with about four inches of seed starter mix or potting soil. Lay the potato on its side, burying at least half of it with the moistened soil mix. Place it in a warm area.

Whether you use water or soil, keep an eye open for the emerging sprouts. Once a sprout gets about 4 to 6 inches long, twist it off the potato and put it into water to develop roots.

After roots develop, you can pot them into potting soil mix for transplanting in late May. If it is already late May, you can set the bareroot slips directly into the garden.

Sweet potato slips are planted in late May after the soil has warmed up. They will not tolerate frost.

Choose a sunny spot in the garden. A raised bed is best because it warms up quickly.

You can warm the soil by setting black plastic mulch over the bed. Poke holes in the mulch about 18 to 24 inches apart. Transplant the slips into the holes. Keep the soil fairly moist until the slips get established.

Sweet potatoes require very little care over the growing season. Your major foe will be deer who love to eat the vines. You can eat the vine tips, too. They are delicious and very nutritious.

Row covers can be used to generate more heat for your plants. Apply them for a few weeks after planting and then again in early fall before the harvest. These lightweight, clear blankets accelerate growth, shield the vines from deer and protect plants from light frosts.

You can enjoy delicious, homegrown sweet potatoes for Thanksgiving and well into next spring. Now is the time to get started.

For more information about gardening, contact your local NDSU Extension agent. Find the Extension office for your county at https://www.ag.ndsu.edu/extension/directory/counties.