I wanted to plant something different in my vegetable garden this year. I decided on sweet potatoes which are grown from slips which I grew myself, rather than seeds.
What are Sweet Potatoes?
Sweet potatoes (Ipomoea batatas) are perennial vines which are related to morning glories. They are not related to potatoes which are members of the nightshade family. The nightshade family includes peppers, eggplants and tomatoes as well as potatoes.
Sweet potatoes are native to Ecuador. They are also found throughout Polynesia. It is thought that the intrepid Polynesian voyagers visited Central America and brought back sweet potatoes to their home islands.
Sweet potato vines have can grow anywhere from 10 to 16 feet in length. The leaves are heart-shaped similar to their morning glory cousins. They are 2 to 5 inches in length. The flowers are also very much like morning glories. They are trumpet-shaped and can be pink, lavender or purple. They last only one day before falling off.
Sweet potatoes do produce seeds, but those are only used for breeding purposes because sweet potatoes need to be pollinated by a different variety. You will not get seeds if you have planted a single variety of sweet potatoes in your garden.
Pollination is done by bees and other insects. Once pollinated, a seed capsule grows at the base of the flower. It takes 4 to 6 weeks for the seed capsule to mature. Each capsule contains 1 or 2 brown or black seeds.
How to Grow Sweet Potato Slips
Most gardeners purchase sweet potato slips from their local plant nursery, but you can grow your own if you prefer. You can start with sweet potato tubers that you have grown yourself or you can purchase organic sweet potatoes at the grocery store. You want organic or your own home-grown tubers because regular sweet potatoes that you see in the store have been treated with chemicals to prevent them from sprouting. Organic standards do not allow for the use of chemicals.
Start your slips 6 – 8 weeks before you plan on planting them. When you get your tubers home, soak them for 2 hours. Then you can suspend them in a glass with toothpicks. Stem end up, please. If you prefer, you can start your slips in soil. Fill a pot halfway with potting soil, then place your tuber, stem side up, in the pot and add cover it with 2 inches of soil. Place the pot in a sunny window and keep the soil moist.
When you are ready to plant, cut your slips away from the tuber, about 1 inch around. Your slips should be 8 to 10 inches long when they are ready to plant.
How to Grow Sweet Potatoes
Sweet potatoes need full sun and well-drained soil. Avoid using fertilizers that are high in nitrogen. That will produce a lot of vines and foliage, but not many tubers.
The slips need warm weather and warm soil to grow. Wait until nighttime temperatures are above 50°F before planting your slips. After you have planted your slips, if you have a cold night with temperatures below 50°F, cover your plants to keep them warm.
Before planting your slips, the soil temperature should be at least 65°F four inches down. If your soil is not warming, you can cover it with black plastic to hurry it along.
You can plant your slips in rows or mounds. If planting in rows, the rows should be 36 to 40 inches apart to allow for the vines to sprawl. Plant your slips 12 inches apart and 4 to 6 inches deep. If planting in mounds, make your mounds 8 inches tall. Plant your slips 4 to 6 inches deep in mounds that are 36 inches apart to allow for the vines to sprawl.
Once planted, keep the soil moist for the first week as the plants establish their roots. After that, 1 inch of water per week should suffice. A good rule of thumb is that more water equals more tubers.
Keep your vines well-weeded. Instead of pulling up the weeds, which will disturb the growing roots of your vines, cut them off at the soil level. Keep doing this until the weeds finally die and stop coming up. As the season progresses and your vines grow, they should shade out most weeds, reducing the need to weed.
How to Harvest Sweet Potatoes
You can harvest sweet potato leaves for greens at any time during the growing season. Be sure to leave enough foliage to feed the growing tubers. The tubers should be harvested before your first frost. Harvest them when they are 5 to 6 inches in length and 2 inches in diameter.
When you are ready to harvest your sweet potatoes, cut off all of the vines down to the soil level. Then use a garden fork to carefully dig around the plants and lift the tubers from the ground, trying not to damage the skins.
Once out of the ground, brush off any clumps of soil, but do not wash the tubers. Washing the tubers can result in them rotting during storage. Allow the tubers to dry out completely before storing them. This is known as “curing.”
How to Store Sweet Potatoes
Sweet potatoes should be stored in a cool, dry, well-ventilated area away from light, at room temperature or a little cooler (55–65°F). Do not refrigerate raw sweet potatoes. Cold temperatures will give tubers a hard core and affect the flavor.
Properly cured sweet potatoes can be stored for up to 12 months without refrigeration.
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