The roots of a sweet potato plant grow underground, while the vines of the plant grow above ground. But what about the tubers – the part of the sweet potato that you eat?
So, do sweet potatoes grow in the ground or on a vine? Sweet potatoes grow in the ground as tubers, where the plant stores starches made of sugar. These tubers are the part of the plant that is harvested and eaten. Tubers will eventually sprout and produce slips, which can be planted to grow more sweet potato plants.
Of course, you can also propagate sweet potatoes from vine cuttings if you like. However, planting sweet potato slips grown from tubers is a more common method of planting.
Let’s take a closer look at how sweet potato tubers and vines grow. We’ll also answer some common question about growing and harvesting sweet potatoes.
Do Sweet Potatoes Grow in the Ground or on a Vine?
Sweet potato tubers grow in the ground. A sweet potato plant uses its tubers to store energy in the form of starches (made of sugar).
Normally, the tuber will store these starches over the winter, during a period of dormancy to avoid cold weather. When the soil warms up in the spring, the tuber will use the starches to sprout and produce slips for reproduction (more on this later).
Sweet potato tubers often have a brown or purple skin, although it can also be white, yellow, or red. The flesh inside of a sweet potato is often orange, but it can also be white, yellow, red, or purple.
Sweet Potato Vines and Leaves
Sweet potatoes do have vines, which grow above the surface of the soil. According to the University of Michigan Extension, a sweet potato is a type of tropical vine, which is native to the Americas.
The vines of sweet potato plants tend to crawl along the ground as they grow in every direction. The vines cover lots of ground very quickly. In fact, the leaves create so much shade that weeds often have trouble growing near sweet potatoes!
If you like, you can use cuttings from a sweet potato vine to produce more plants. A vine cutting placed in water will form roots and grow.
You can later transplant the rooted cutting into soil to grow a new sweet potato plant. Or, you can keep the vine in water instead and grow it as a houseplant. Another way to produce more sweet potato plants is by using slips, which sprout from the tubers (more on this later).
Do Sweet Potato Vines Climb?
Sweet potato vines can climb, but they do not climb naturally. Sweet potato vines prefer to crawl along the ground, similar to tomatoes or bush beans.
However, you can give sweet potatoes support and secure them to allow climbing. This can be helpful in a small garden or when using container gardening or square foot gardening, where space is at a premium.
One way to support sweet potato vines is to plant them at the base of a trellis and let them climb.
Another option is to drive stakes into the ground, just like you would with tomatoes. You may want to drive the stakes into the ground before planting a sweet potato plant, to avoid damaging the roots of the plant.
Once the stake is secure, use twine to tie the vines to the stake every 6 to 12 inches (15 to 30 centimeters). This will keep the plant from falling over, and prevent it from invading the space of nearby plants.
How Long Do Sweet Potato Vines Grow?
Many varieties of sweet potatoes have vines that will grow up to 6 feet (1.8 meters) wide as they crawl along the ground. The vines of a sweet potato plant can grow in all directions from where the plant was originally started.
The height of a sweet potato plant crawling along the ground will be limited to between 6 to 18 inches (15 to 45 centimeters). If you let your sweet potato plant crawl up a trellis or tie it to a stake, it will grow much taller and take up less ground space.
Do Sweet Potato Vines Flower?
According to Wikipedia, sweet potato vines will sometimes produce flowers. The flowers of a sweet potato are white with a purple center.
However, these flowers usually only appear in areas where there are less than 11 hours of daylight per day.
Sweet potatoes are perennial, meaning that they are capable of growing back year after year. However, a freeze will kill will them, and they do not tolerate frost well.
As a result, sweet potatoes are usually grown as annuals and planted every year from sweet potato slips.
Sweet potato slips are vine pieces with two or more leaves. Slips grow from a sweet potato tuber after it sprouts.
Do you want to grow your own sweet potatoes? If so, you can learn all about planting sprouted sweet potatoes in my article here.
Note: sweet potatoes are a type of root vegetable. Potatoes and yams are also root vegetables that grow their tubers in the ground, and they are both different from sweet potatoes.
Can You Eat Sweet Potato Leaves (Greens)?
Yes, you can eat sweet potato leaves. You can use them fresh in salad as “greens”, to replace lettuce, and put some dressing on them.
You can also steam sweet potato leaves like spinach. Don’t forget to add some garlic and onions sautéed in olive oil to go with the leaves!
Sweet potato leaves may be a little bitter, but they have lots of nutrients. The best part is that you can enjoy sweet potato leaves while waiting for the tubers to mature – check out this article from UC Davis to learn more.
Harvesting Sweet Potatoes
After 3 or 4 months of growing, sweet potato tubers will be ready for harvest. But how do you know exactly when to take them out of the ground?
How Do You Know When Sweet Potatoes Are Ready to Harvest?
Sweet potato tubers grow in the ground, but you can look above ground to tell you when it is time to harvest. Just pay attention to the leaves and vines, which will be a good indication.
When the leaves and vines begin to dry out and turn yellow, it is getting close to harvest time. Sweet potato tubers will usually mature between 85 and 120 days after planting.
However, there are some exceptions, such as unseasonably cold weather or an early fall frost. According to the University of Maryland, you should harvest the tubers right away if the sweet potato vines are touched by frost.
How to Harvest Sweet Potatoes
After the leaves and vines begin to dry out and turn yellow, dig up a sample sweet potato to see if the tubers are ready for harvest. Most of the tubers will be found in the top 6 inches (15 centimeters) of soil.
If the sweet potatoes are ready to harvest, you can cut away and remove the vines of the plant to make your work easier. Use a pitchfork instead of a shovel to dig when harvesting your sweet potatoes. This will avoid cutting and slicing the sweet potatoes.
Sweet potato tubers are easily damaged, so be careful when harvesting and handling them. Use the bruised or cut tubers for cooking first.
How Many Sweet Potatoes do You Get from One Plant?
A single sweet potato plant can produce many sweet potatoes. The Iowa State University Extension says that 50 sweet potato plants will yield one bushel (50 pounds) of sweet potatoes, or 1 pound per plant.
A medium sweet potato weighs 4 ounces on average. That comes out to about 4 medium sweet potatoes per plant. Of course, it all depends on the variety, the climate, the soil, and the care you give your plants.
Can You Eat Sweet Potatoes Right after Harvesting?
Yes, you can eat sweet potatoes right after harvesting. However, they will become sweeter if you let them cure (age) for a while.
According to Bonnie Plants, you should put the sweet potato tubers in a warm area at 80 to 90 degrees Fahrenheit (27 to 32 degrees Celsius) for 10 days to allow them to cure. This will cause some of the starches to convert to sugars, making the flesh sweeter.
How to Store Sweet Potatoes
To store sweet potatoes, brush the dirt off with a clean brush or rag. Do not wash them before storage, since this will increase the chance of rot.
According to the Old Farmer’s Almanac, you should keep sweet potatoes at around 60 degrees Fahrenheit (16 degrees Celsius) for ideal storage. At this temperature and with high humidity, the sweet potatoes can keep for around 6 months.
Now you know that sweet potato tubers grow in the ground with the roots, while the vines grow above ground and climb. You also know when and how to harvest sweet potatoes from the ground.
I hope you found this article helpful – if so, please share it with someone who will find the information useful.