It’s time to think about sweet potatoes

Sunday, 19 November 2017, 07:18:04 PM. Are sweet potatoes on your Thanksgiving menu? A favorite winter veggie, they are front and center on mine. Typically thought of as a southern crop, a few years ago the University of New Hampshire started experimenting with growing them in our climate....

Are sweet potatoes on your Thanksgiving menu? A favorite winter veggie, they are front and center on mine.

Typically thought of as a southern crop, a few years ago the University of New Hampshire started experimenting with growing them in our climate. They have had great results, so I had to give it a try.

I have been growing them for a few years now with varying degrees of success.

Sweet potatoes are not related at all to regular potatoes, so they are grown differently. Instead of planting chunks of seed potato in the ground you plant rooted sprouts called “slips.”

To start my first crop I bought an organically grown sweet potato (variety unknown) to start the slips from. Non-organic ones from the grocery store usually have been treated not to sprout.

About two months before the last frost date, I planted the whole thing on its side in a large container of fluffy potting soil. As the sprouts developed, I snapped them off and rooted them in individual pots where they could grow until the soil outside warmed up. You can also sprout them in water by suspending the potato, skinny end down, in a glass of water. Each potato can have as many as twenty “eyes” or growing points that will form sprouts.

This year none of my saved sweet potatoes would sprout. I think we had eaten all the good ones, so we resorted to buying slips from a seed company. The plus side was that we could choose from several named varieties. We chose Beauregard since that is one that UNH had good luck with.

Once the weather warms up and the soil temperature is above 60 degrees, plant your slips about 12 inches apart in raised beds. We planted them in bushel-basket-sized containers one year, and they did okay. Many of the potatoes were L-shaped, like they had hit the sides and bottom of their pots and took a sharp turn. Those planted in an open bed are straighter. They prefer sandy soil on the sweet side.

Don’t enrich the bed with high nitrogen fertilizer or they will grow lots of leaves but won’t produce many potatoes.

We used black landscape fabric to warm the soil and to keep weeds down. The slips we purchased arrived looking half dead but we planted them in slits cut in the fabric and they perked right up.

Soon lush heart-shaped leaves covered the bed. Sweet potatoes are in the morning glory family so when they bloom they have similar funnel-shaped flowers. Since they are the only vegetable we grow that is in the Convolvulaceae family they are great to grow in rotation with nightshades like tomatoes and peppers, cole crops, or the squash family.

Sweet potatoes need a long season of growth – at least 90 days for most varieties – to form their fat tubers. Once planted they require little or no attention – no hilling needed.

This year we did not harvest them until late October, once frost finally knocked down the vines. After digging, we let them dry a bit, then placed them in a warm humid greenhouse to cure. They need about a week at temps above 85 degrees and 85 percent humidity to convert their starch to sugar and to toughen up the skin for storage.

After curing, they should be stored at 55 to 60 degrees. Temperatures any colder than that will cause them to form a hard inner core and develop spots that lead to rot.

Sweet potatoes are one of the most delicious and nutritious foods we can grow. Just one cup contains four times the RDA of betacarotene. They are rich in vitamins A and E, high in fiber, and are an excellent source of potassium and vitamins C and B6.

One medium-sized potato has only 120 calories, is low in sodium, has no cholesterol, and is fat free. They seem to get sweeter the longer they are stored so no need to add marshmallows or glaze them with honey.

Next spring try setting down some southern roots. Come Thanksgiving you’ll have one more thing to be thankful for.

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