How to Grow Sweet Potatoes

sweet potatoes
Root vegetables like potatoes and carrots generally need somewhere between sun and shade. Mike Mozart/flickr

Growing sweet potatoes is a “Back to the Future” experience for many people.

Remember when you were a kid and would stick three toothpicks in a sweet potato, partially fill a glass with water, put the potato in the glass and rest the toothpicks on the rim? Wasn’t it fun to watch as the potato sprouted roots and green sprigs?

As an adult, that’s all you need to do to prepare sweet potatoes for your vegetable garden.

Best of all, you can start this project for these warm-growing tubers indoors in February when it’s still the middle of winter.

And if you want, don’t even use the toothpicks. Just rest the potato on the bottom of the glass.

In case you’ve forgotten — or never experienced — this childhood science project, here’s a 10-step guide for starting sweet potatoes indoors and transplanting them to the garden.

1. You can use sweet potatoes from your local grocery as long as they are labeled organic – non- organic potatoes tend to be treated to keep them from sprouting. If you are looking for a special variety, you can buy sweet potato “slips” from a local farm or garden outlet or order some from a garden supplier. The “slips” are the green stems and leaves that emerge from the potato.

2. Place the sweet potato in the glass and fill it half way with water. It doesn’t matter which end of the potato is put into the water.

3. Every three days, empty the water from the glass and replace it with fresh water.

4. While the potato is sprouting roots and vegetative growth, prepare a place in the garden to plant the slips. Just loosen the soil, add compost or aged manure and push the row for the potatoes into a mound about six inches high.

5. In late spring, after danger of frost, remove the slips from the potato (they should be six-eight inches tall) and plant them in the center of the mounded row about 15 inches apart. Some people put the sprigs in a fresh glass of water until they have sprouted roots. But that’s not necessary. They can be planted directly into the garden. Transplant shock will be reduced if the slips are planted in the cool of the evening rather than in the heat of the day.

6. In either case, water them well to help them get established. Continue to give them water as needed during the long summer growing season.

7. Fertilize with fish emulsion or another organic fertilizer according to package directions.

8. Keep the mound and the area along the sides of the mound free of weeds. The potatoes are forming and growing below the soil surface, so take care not to damage the potatoes when weeding.

9. Harvest the potatoes in the fall when frosts will cause the tops of the plants to turn black. Be careful when digging them up. You’ll be amazed at how many potatoes each slip produces (up to seven pounds!).

10. Sweet potatoes store well, but not in the refrigerator. They will keep the longest if they are put in a warm place for one-two weeks and then moved to a dry cooler place, preferably one where the temperature will stay at 50-55 degrees.