Archive for Thursday, May 30, 2013

Garden Calendar: Sweeten up your garden with sweet potatoes

May 30, 2013


Looking for something easy to grow that is a great late-in-the-season addition to the vegetable garden? Try growing sweet potatoes this year. They are bothered by few pests, thrive in hot, dry weather, and produce a crop that will last through the winter months if you let them.

Sheila Reynolds, a Master Gardener who produces sweet potatoes in her home vegetable garden in northwest Douglas County, agrees about how easy sweet potatoes are to grow.

“They are so pest-free and productive,” she says. “In 2010, we grew about 110 pounds of potatoes from just fourteen slips.”

Sheila Reynolds plants sweet potato slips in her garden in rural Douglas County.

Sheila Reynolds plants sweet potato slips in her garden in rural Douglas County.

Sheila Reynolds prepares to plant a sweet potato slip in her garden in rural Douglas County.

Sheila Reynolds prepares to plant a sweet potato slip in her garden in rural Douglas County.

Sweet potatoes

Sweet potatoes

That is a lot of potatoes, but their storability is another strong point. Properly cured and stored sweet potatoes last several months. Curing also helps to develop the sugars that give the potatoes their name and distinguish them from Irish potatoes.

The key to planting is to wait until the soil warms — just remember that the plants are native to the tropics. In northeast Kansas, they can typically be planted anytime between mid-May and the first part of July. Instead of planting the potatoes themselves, ask for slips — stems with a few leaves and roots. You can also produce your own slips — Reynolds suggests saving one or two from your crop each year to use the following year.

“You just suspend the potato in water,” she explains. Many people use toothpicks to hold the potato about halfway out of a jar with water covering the lower half of the potato. Sprouts will grow from the exposed portion of the sweet potato. “Then you break sprouts off when they are about six inches tall.”

Reynolds prefers to root the slips or sprouts in water prior to planting in the garden. They can also be rooted in a tray of moist sand. (The potato itself could also be held in moist sand instead of the jar method to produce sprouts.) The entire sprouting/rooting process generally takes about six weeks.

Avoid using grocery-store-purchased sweet potatoes to produce your own slips as there is potential for transferring plant pathogens into your soil. Food-grade potatoes may also be treated to prevent sprouting.

Slips should be planted about 12 inches apart in wide rows. Reynolds notes that she has seen vines up to 15 feet long in her garden, so a trellis may be necessary if you are limited on space. Slips may require watering in the first few weeks or in extended periods without rain, but otherwise you can just sit back and let the potatoes grow all summer.

Harvesting can begin as soon as the potatoes form underground, but they will get bigger if left to grow into the fall.

“We prefer to wait until right before the first frost,” Reynolds says. Once dug, potatoes should have as much soil as possible cleaned off them and then air-dried.

The curing process that follows is key. The crop needs to be held in a warm, humid location for seven to 10 days. The ideal temperature is 80-90 degrees F. Reynolds uses a small bathroom in her house for the curing process. There, she can fill the bathtub with water to create humidity and turn on a small space heater to keep the room warmer than usual. Post-curing, sweet potatoes should be stored at around 55 degrees F for best longevity.

Sweet potatoes can suffer damage if exposed to temperatures below 50 degrees, so take care to keep them inside once they are out of the ground in the fall.

There are several varieties that do well in this area, but Beauregard is the most common and one of the best performers.

When it comes to cooking your fresh, homegrown sweet potatoes, ask around for recipes. Sweet potatoes can be roasted, baked, mashed, fried or prepared in many types of dishes. The potatoes are high in Vitamins A and C, calcium, iron, niacin and riboflavin, and are a good source of protein.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or an Extension Master Gardener with your gardening questions at 843-7058 or


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