Garden Journal

Sweet potatoes are in the morning glory family

March 4, 2015

A slip can be a minor mistake or a lady’s garment, a small thin person or a landing place for boats, but slips to gardeners are simply shoots or cuttings. Some of our favorite plants grow from slips, such as the sweet potato.

Sometimes what we know just ain’t so. Take sweet potatoes and regular, or Irish, potatoes.

Both grow underground, but regular or Irish potatoes (Solanum tuberosum) are in the nightshade family along with tomatoes, eggplant, and peppers. Sweet potatoes (Ipomoea batatas) are in the morning glory family. Anyone who has dug up morning glory roots can see the similarity. Sweet potatoes are a good source of beta-carotene, vitamin A, vitamin C, vitamin B6, calcium, potassium, iron and manganese. The leaves are edible and can be steamed or eaten raw. There are even ornamental sweet potatoes such Margarita, with bright chartreuse leaves.

While you can plant Irish potatoes in cool weather, you have to wait until hot weather to plant the tropical sweet potato.

Irish potatoes are grown from pieces of potato, but sweet potatoes are grown from small shoots called slips that sprout out of the potato itself.

You can order sweet potato slips by mail, or you can easily grow your own.

To be sure your sweet potato is untreated with growth retardants, buy organic sweet potatoes. You can use a whole sweet potato or one sliced in half. Poke toothpicks around the middle of the potato and hang the sweet potato (or half sweet potato if you sliced them) so that the bottom part of the sweet potato is under water. You can also just put the sweet potatoes in a shallow pan with enough water to submerge the lower inch or two of the sweet potato. Put them in bright light, but out of direct sunlight. Soon your sweet potatoes will sprout roots and in just five or six weeks you will have sprouts.

Break the slips off the sweet potato tuber by snapping them off. Some slips will have roots, but even if they don’t, they will root quickly, so don’t discard them. If the roots are fully developed you can transplant them directly into individual pots.

Put the slips with few or no roots into a tall glass of water, and in two weeks enough roots will form so they can be potted up or planted directly in the garden after the ground warms up and all danger of frost has passed. Plant the slips in full sun 10 to 12 inches apart, three inches deep. Water well after planting.

Black plastic mulch will keep the ground warm for a better crop. Ideal soil pH is 5.0 to 6.5.

Your sweet potato plants will spread with long, vigorous vines, though some varieties are bush types with short vines.

You can harvest your sweet potatoes at any size, but it may be three to four months before they are ready. Use a garden fork to gently lift them from the soil and prevent damaging them.

Oh, and a sweet potato is not a yam. True yams are white-fleshed tubers rarely found in American markets, which is why even canned yams are labeled “sweet potatoes.”

Start your own sweet potato slips, and you will have a truly self sufficient garden. You can microwave them whole or boil and bake them as a side dish, make sweet potato french fries, or candied sweet potatoes with marshmallows.

Best of all is a smooth and creamy sweet potato pie which, thanks to growing your own slips, is a good way to give hunger the slip.

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