Love sweet potatoes? Learn how to grow sweet potato vine for an antioxidant punch even more potent than the revered root. (With bonus recipe!)
How to Grow Sweet Potato Vine: Antioxidant Powerhouse
I love sweet potatoes. The roots are one of the most delicious, versatile, high-calorie, easy-to-grow, long-storing veggies around.
Many homesteaders who have a long growing season stockpile sweet potatoes in their garden beds from spring to fall—and then in their cellar from fall to spring. Surprisingly, though, most sweet potato growers don’t realize that the vines are also an incredible food source.
This article on growing sweet potato vines is part of our Green of the Month series. Click here to read the rest of the articles in the series.
If you have a crop of the beloved root in the ground now, keep reading to learn how to grow sweet potato vine so you can start enjoying the greens while you wait for your roots to be ready to harvest and cure.
The Goods on Sweet Potato Vine
The nutritional benefits of sweet potato roots are well known. But if you are like I was just a few years ago, you may not be aware of how fabulously nutritious sweet potato vines are. So let’s get to the goods on sweet potato vines.
#1: Antioxidant Hero With Cancer-Fighting Clout
Sweet potato vine is a low-calorie, high-vitamin green that’s packed with folate, potassium, magnesium, and vitamins A and B6. Vitamin content aside, though, there’s an even more important reason to eat your sweet potato greens. According to Shahidul Islam, professor of plant science at the University of Arkansas at Pine Bluff, “Sweet potato leaves contain more total polyphenols than any other commercial vegetables, including sweet potato roots and potato tubers.”1)https://www.uaex.edu/publications/PDF/FSA-6135.pdf
In case you’re not familiar with polyphenols, they are a class of antioxidants known to be particularly effective at helping to prevent cancer. Also, according to Mr. Islam, these potent leaves may have anti-diabetic and antibacterial properties.
#2: Prolific Producer in Hot Weather
During the hottest months of the year, sweet potato vines are one of the most prolific leafy-green producers in my garden. Also, anyone who knows how to grow sweet potato vine knows you can easily use your existing vines to make new plants, even in extreme heat when most leafy greens will not germinate.
#3: Incredible Edible
The antioxidant factor alone is enough to make me want to eat my sweet potato greens. But these vines are actually delicious too!
The young leaves are great chopped and added to salads. The more mature leaves are wonderful stir-fried with garlic and olive oil or butter. The really mature leaves and vines, pulled up when you start to harvest, make a great substitute for spinach in dishes like creamed spinach and palak paneer.
Read to the end for a dreamy Curried Creamed Sweet Potato Greens recipe!
A Few Cautions About Sweet Potato Vines
As a mostly self-sufficient homesteader living in USDA Hardiness Zone 7a, I don’t see many downsides to growing sweet potato vine. However, these vines can be problematic for some growers.
Sweet Potato Plants Are in the Morning Glory Family
Sweet potatoes belong to the morning glory family. As you learn how to grow sweet potato vine, here’s a word to the wise: Morning glory-related plants can be notoriously invasive.
In cold climates, the vines are instantly killed by frost, and the tubers will rot in the ground if left there over the winter. So there are no risks that sweet potatoes will get out of control.
In climates that stay above freezing, though, sweet potato vines can become invasive if left unharvested. The plants also self-propagate, so they can spread to new areas quickly.
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Also, unless you plant bush-type sweet potatoes (which are much less productive), you should expect your sweet potato vines to overgrow their beds and attempt to move into neighboring areas. Even though you only need to plant them 3 feet apart for root growth, they’ll cover about 6–8 feet of garden bed space.
Sweet Potato Vine Is Picky About Growing Conditions
Despite the fact that sweet potato plants have low nitrogen needs and can even grow in poor soils, they are pretty picky about watering for the first 30–40 days after planting. If they get too much or too little water, the plants will not thrive.
Also, though they grow well in hot weather, they are very intolerant of cold weather. Even a few cool nights close to 40ºF can stress the plants to the point of death. For best results, you don’t even want to put your plants in the ground until the soil reaches at least 60ºF.
How Sweet Potatoes Grow
Before we dig into the details of how to grow sweet potato vine for its savory greens, let’s take a step back and look at the basics of how sweet potato plants are designed to grow in nature.
Relationship Between Vines and Roots
Unlike most plants, which need elaborate underground root systems to support healthy leaves and set above-ground fruit, sweet potatoes need elaborate above-ground leaf systems to grow large roots.
In Medusa-like fashion, sweet potato vines snake out from the mother plant—spreading, climbing, and occasionally setting new shallow roots to anchor the vines in place. When leaf growth reaches critical mass, the plant begins to fill underground storage roots with sugars and nutrients drawn from sun and soil.
In prepared garden beds, root storage usually starts at around 30–40 days after planting. Depending on the variety planted and the growing conditions, it can then take up to 6 months for the roots to reach their full potential size.
Rooting Out the Root’s Function
The purpose of this elaborate underground root storage system, from the plant’s perspective, is survival. Those roots are a reserve of food that the plant can draw on during periods of poor growing conditions. For example, in an extended drought, nutrients and moisture can be drawn from the roots to sustain the vines until rain comes.
Also, if animals eat the above-ground leaves and stems, the stored energy in the roots can be used to grow new vines and start the cycle of gathering and storing nutrients all over again.
Starting Sweet Potato Slips
At home, we use those sweet potato roots not only for eating, but also to start new plants. Taking advantage of the roots’ survival mechanisms, we force the root to produce what we call “slips” or sweet potato plant starts.
Slips From the Root
To do this, simply put the whole root, or a cutting from the root, in contact with water or moist soil. This wakes the root up from dormancy and encourages it to grow new vines and create more storage roots. As the vines and roots form, you can separate them from the root and treat them like new plants.
Slips From a Mother Vine
Starting new sweet potato vines from the root can sometimes lead to transmission of diseases. Roots can host fungal pathogens that may be transferred to new plants started directly from those roots.
Even if roots are infected, those fungal pathogens generally do not pass through to the vines. So, to minimize the risk of fungal pathogen transmission, you can instead start new plants from mother vines.
In nature, when the plant begins to vine, some of those vine stems make contact with the soil and grow new roots. When the roots get deep enough, they start to create their own storage roots.
Once established, if these new root systems get separated from the mother plant, they become a mother plant and begin making their own new baby plants. This process is called “layering.”
If you want to grow lots of sweet potato greens for eating, layering with sweet potato slips is a great way to create disease-free plants with minimal work.
Tips on How to Grow Sweet Potato Vine … and the Roots!
If you aim to grow sweet potato plants for their roots, you can harvest about 20-30% of your vines for fresh eating. Alternately, you can create new plants specifically for the purpose of growing lots of those antioxidant-rich greens.
Harvesting Leaves From Plants Grown for Roots
If sweet potato roots are your goal, overharvesting the vines can lead to a reduction in root size. In theory, you can harvest 20-30% of the leaf mass for fresh eating if your plants are growing vigorously. However, the hard part is figuring out exactly how much that is over the life span of the plant.
Personally, my method is to harvest every fifth leaf on a vine once the vines are abundant (usually around 80 days after planting). I have 6 beds with vines, so I harvest from a different bed each week. That way, I only end up harvesting leaves from a plant once every 6 weeks. So far, this technique has not reduced the root size of my winter-storage sweet potatoes.
Additionally, when it comes time to harvest my sweet potato roots, I use the portions of the vines that are still healthy to make large batches of the curried creamed greens for freezing.
Growing Sweet Potato Plants for Vines Rather Than Roots
I love sweet potato greens so much that I also grow some plants specifically for the greens. That way I can harvest heavily without worrying about reducing root production.
Once your vines are growing, you can easily layer your vines to start new plants as described earlier. Sweet potato vines are so eager to set roots that you can take cuttings from your vines and plant them even when they don’t have roots yet. As long as you keep your cuttings well-watered, they will grow roots quickly.
I like to start a few new plants each week to keep a steady supply. When the vines get about 3 feet long, I harvest everything back to a few inches in length. When they get 3 feet long again, I cut them.
Sweet potato plants grow well in a variety of conditions. They can tolerate pH ranges from 4.5 to 7.5, though they tend to grow best with a pH closer to 6.
Any soil texture type with the word “loam” in it, such as clay-loam, silty-loam, or sandy-loam, is suitable for growing sweet potato vines. If you have heavy clay soils, you’ll need to incorporate lots of organic matter prior to planting sweet potatoes in order to get a good harvest.
If you aren’t sure of your soil type, check out this article for details: “Clay, Sand, Silt, or Loam? Discover Your Garden’s Soil Texture In 5 Easy Steps.”
Sweet potatoes are highly susceptible to fungal pathogens if planted in areas prone to holding water. Choosing a location with good drainage is critically important.
Sweet potato plants don’t require much nitrogen or phosphorous, but they have high potassium needs. Amending your soil with compost that included banana peels can help.
Also, if your soil is short on potassium, adding a light dusting of wood ash on your garden bed can help. Make sure you can still see your soil under your wood ash to avoid overdosing your soil. Or for more precision, use bagged kelp meal fertilizer to add potassium.
For best results, perform a soil test to ensure adequate potassium.
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Sweet potatoes for vines and roots grow well on 3-foot centers. If you plan to trellis your vines, you can reduce that spacing to plant about every 2 feet apart.
Trellising the vines makes weeding and harvesting greens easier. However, the vines will not be able to layer if grown vertically. If you plan to use an existing vine to make new plants, make sure to let your mother plant grow horizontally and in direct contact with soil.
For the first 30-40 days of growing, ensure that sweet potato plants get at least an inch of water per week. Mulch around the plant base to preserve moisture.
Use dark mulch or black plastic in cooler climates to increase the soil temperature around the roots and expedite growing speed.
Weed weekly until the vines take off. Once vines are a few feet long, the plants can withstand some weed pressure, so aggressive weeding is not required.
Note: You can also grow sweet potato vines in containers in sunny areas of your heated house if you want a year-round supply in cold climates!
Varieties of Sweet Potatoes
There are hundreds of varieties of sweet potatoes. Heirloom seed suppliers like Southern Exposure Seed Exchange offer many different types. And although I have never ordered from them, Sand Hill Preservation Center has one of the most impressive collections of sweet potato varieties I have come across.
My two favorite sweet potato varieties are Beauregard and Georgia Jet. They both grow prolific vines and large tubers. O’Henry is also an excellent choice for disease resistance in areas that may be more susceptible to fungal pathogens.
Generally, for the purposes of growing vines, avoid the bush or bunch varieties.
The Difficulty In Growing From Sweet Potato Vine Seeds
Sweet potato vines also flower and produce seeds in the right conditions. The plants generally only flower in the mornings, and the flowers only live for a few hours. Regardless, why don’t we typically use these sweet potato vine seeds to grow new plants?
Pollination is performed mainly by bees, who generally don’t get active pollinating until late morning to afternoon. As a result, pollination of the flowers is rare.
Additionally, the plants tend to set flowers only during periods of stress, such as with irregular watering. Therefore, it’s pretty clear that nature didn’t mean for sweet potato plants to reproduce by seed.
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Still, if you want to have an experience few gardeners will ever get, hand-pollinate all your open flowers using a paint brush. Collect the sweet potato vine seeds, and plant them. If you cross-pollinate different varieties, your outcomes may be completely different than your parent plants. Alternately, you can go the easy route and purchase sweet potato seeds.
Unconventional Growing Tips for Adventure Gardeners
Sweet potato plants make great clay breakers. Prepare a few inches of soil to start plants. Then let the sweet potatoes grow until they die.
When they die, leave the roots in the ground to decompose in place. This creates habitat for soil life and helps break up compacted clay soils.
Sweet! Your Bonus Recipe Is Here…
Curried Creamed Sweet Potato Greens
There are several ways to cream leafy greens. My personal preference is to put about a quarter inch of water in the bottom of a large pot and then fill the pot with bunches of leaves and stems.
After that, put the lid on, turn on the burner, and give the greens a few minutes to wilt. Every few minutes, open the lid and stir the greens to keep them from sticking and to move unwilted greens closer to the heat. Repeat until all your greens are well-wilted.
While there’s still some water in the pot with the greens, add your spices. You can toss in your favorite curry spice mix, or make your own.
For every 4 cups of cooked greens, I use the following spice mix:
- ½ tsp. powdered coriander seeds
- ½ tsp. powdered turmeric root
- ¼ tsp. ground fennel seeds
- ¼ tsp. of some sort of powdered pepper (e.g., cayenne, paprika, gotchu)
- 2 in. fresh ginger, peeled and minced
- 6 large garlic cloves, peeled and minced
- Bit of honey (to counter any bitterness in the greens)
- Salt and pepper to taste
If you want to make your sweet potato greens taste like the spiced spinach in palak paneer, add these optional items too:
- 2 medium sauteed onions
- ¼ tsp. garam masala
- A few methi (fenugreek) leaves if you have them
- Dash of cinnamon
Stir in your seasonings, and allow the extra water in the pan to cook off. When your greens just start to stick, turn off the heat and add one of these options to cream your greens:
- Stick of butter (my favorite)
- ½ c. cream
- ½ c. plain yogurt
- ½ c. of your favorite dairy substitute
Stir your mix. Then use an immersion stick blender to chop your greens in the pot. Or you can transfer your greens to your food processor and pulse until the greens are the consistency of creamed spinach.
Ways to Serve Your Curried Creamed Sweet Potato Greens
You can serve this up as a side dish to your main course. You can spread it over a bed of rice with cashews and call it dinner. This stuff also makes a wonderful savory crepe filling.
In addition, you can blend it into a smooth paste, add bone or vegetable stock, and transform it into a delicious soup.
What Do You Think?
Grow sweet potato plant . . . get sweet potato power! Are sweet potato greens going to be appearing on your dinner table soon? Share your thoughts in the comments below.
This is an updated version of an article that was originally published on September 28, 2018. The author may not currently be available to respond to comments; however, we encourage our Community members to chime in to share their experiences and answer questions!
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Tasha Greer is a regular contributor to The Grow Network and has cowritten several e-books with Marjory Wildcraft. The author of “Grow Your Own Spices” (December 2020), she also blogs for MorningChores.com and Mother Earth News. For more tips on homesteading and herb and spice gardening, follow Tasha at Simplestead.com.