How to Plant, Grow, and Care For Sweet Potatoes
Looking to plant some sweet potatoes, but aren't quite sure where to start? Growing sweet potatoes can actually be quite fun, no matter your skill level as a gardener. In this article, organic gardening expert Logan Hailey walks through how to plant, grow, and care for sweet potato in your garden this season!
They’re not potatoes, nor are they yams: Sweet potatoes are a highly versatile yet misunderstood garden vegetable. These nutritious fiber and carb-rich roots are renowned for their “superfood” health benefits and delectably creamy sweet texture when cooked.
Though they are somewhat shrouded in mystery (are they like potatoes? are they tubers? why do they start from “slips”?), these relatives of Morning Glories are intriguing and straightforward to grow. Sweet potatoes are beautiful plants with edible roots and nutritious greens that will vine through your garden, climb a trellis, and even hang out indoors as a trailing houseplant.
If you’ve been dying to try out a rainbow array of sweet potato varieties unavailable in stores, or you just want to add diversity to your summer garden, this warm-weather root crop is a joy to grow and eat. Let’s dig into how to plant, grow, and care for the most delicious sweet potatoes you’ve ever tasted!
Sweet Potato Overview
Convulvaceae (Morning Glory)
USDA zones 5-11
Late spring or early summer
75° and 95°F is ideal
Parsnips, beets, beans
10-18” apart in rows 30-42” apart
Needs consistent moisture
Days to Maturity
90 to 150 days
Sweet Potato Beetles, Wireworms
Scurf and rot
As one of the oldest root vegetables in the world, the earliest records of sweet potato cultivation date back to 750 BC. With their ability to cure and store for up to a year, the carb-rich smooth flesh has been an important energy source for Latin American cultures.
In the modern day, they are cultivated throughout the U.S., with about 50% being commercially grown in North Carolina. These heat-loving plants can be grown in zones 5-9 as annual vegetables, however they are only perennial in zones 10-11.
Here’s everything you need to know about the history and cultivation of this scrumptious vibrant root.
Defining Sweet Potatoes
Sweet potatoes (Ipomoea batatas) are not potatoes or yams, but rather a tropical root vegetable. They are perennial vegetables (herbaceous perennial vines to be exact) most commonly grown as an annual vegetable in temperate gardens.
The popular orange-fleshed vegetables are often mistakenly called tubers or potatoes, but they are in fact root vegetables that grow from the enlarged tips of winding stems beneath the surface of the soil.
As a member of the Morning Glory (Convulvaceae family), sweet potatoes are related to bindweed, morning glory varieties, water spinach, and the wood rose. They thrive in warm, tropical climates, however farmers and gardeners have adapted their growing methods to produce them in temperate northern regions as well. Most varieties require 90 to 150 days, or at least 4 or 5 completely frost-free months to produce full-size roots.
Sweet potatoes are a humble and underappreciated “superfood”. The nutrient-dense vibrant flesh can be creamy white, yellow, purple, or orange-tinted. The fibrous orange, tan, or purple skins are rich in beta carotene and antioxidants.
Their pale to dark green edible leaves are often used as a salad green in hot southern summers. When the leaves die back and the roots are ready to be harvested, the entire plant is pulled and sweet potatoes are removed from their underground stems to be prepared for curing and storage.
Where Do Sweet Potatoes Originate?
Like potatoes, sweet potatoes hail from Central and South America, where they have been a staple in indigenous food cuisines for millenia. Ancient records of their cultivation show origins in Peru around 750 BC, however newfound archaeological records also reveal sweet potato relatives growing as early as 2500-1850 BC in Polynesia.
Due to the resemblance between the Polynesian word for sweet potato kuumala and the Quechuan/Andean native word cumal, anthropologists speculate that the orange tubers traveled over the Pacific from the west coast of South America long before historians initially thought.
Needless to say, by the time European conquistadors arrived in Central America in the 15th century, sweet potatoes (called camote) were a well established crop and staple food in the cuisines of Peru, Mexico, Chile, Bolivia, Ecuador, and the Philippines. Samples were taken back to Spain and Belgium to attempt small scale cultivation. Captain James Cook also picked up the root vegetable in Polynesia in the late 1700s and contributed these genetics to the ever growing germplasm of sweet potato breeding projects back in London.
The tropical vines were never widely successful in northern Europe without their ideal hot, moist native conditions. However, when they were introduced to American colonists in the mid 1600s, the crop finally took off as a staple crop in the American south.
The name “sweet potato” is full of linguistic and botanical confusions. To start with, sweet potatoes aren’t actually potatoes at all. While regular potatoes are members of the Solanaceae family (along with tomatoes, peppers, and eggplant), sweet potatoes belong to the morning glory family, Convulvavaceae.
Sweet potatoes (Ipomoea batatas) were first confused with regular potatoes (Solanum tuberosum) when Christopher Columbus brought the orange-fleshed roots back to Spain in the 1500s. Europeans called them potatoes due to the similar rounded shape and starchy texture. Further confusion arose when the native Caribbean Taino word for sweet potato (batata) was confused with the Italian word for Solanaceous potatoes (patatas).
To make matters more confusing, they later became conflated with African Yams. Though they are often mislabeled or used interchangeably on supermarket shelves, true yams (Dioscorea batatas) are completely unrelated.
The tropical yam vine is native to Africa and has black or brown thick bark-like skin and a tan flesh with nutty flavor and slippery or sticky texture. They are not sweet like a sweet potato, and instead used for making doughs, breads, thick porridges, and different types of custards.
True yams can grow over 7 feet long and even weigh up to 150 pounds! Sweet potatoes are far humbler, typically averaging 4 to 6” in length and weighing about 4 to 6 ounces (however, the Guinness Book of World Records documented an exceptional 81 pound sweet potato grown by a gardener in Spain)! Nonetheless, the American sweet potato is best enjoyed at a moderate size when its tender, dry, sweet flesh can shine in the kitchen.
Sweet potatoes are not typically grown from seed. Instead, they are propagated vegetatively via pieces of stems called “slips”. Slips are available from seed companies and nurseries in the spring. These shoots are technically rootable cuttings that are grown from mature plants and shipped to farmers and gardeners around the country.
You can certainly grow your own slips, but the quickest way to get started is to order certified planting material from a reputable source and skip to the propagation steps below.
Sweet potato slips are essentially sprouts that are snipped from the lush growth of a mature Ipomoea batatas plant. With the proper setup, you can grow your own slips from a root that you already have in your kitchen.
In your home, you can produce slips in two main ways:
- Use toothpicks to suspend half of a root in a jar of water and allow it to sprout over the course of 5-8 weeks. Provide warmth with a seedling heat mat and keep the water fresh.
- Plant a root in a shallow tray of soil, keep it moist, and wait 2-3 weeks for sprouts to grow.
Either way, be sure to start with an organic sweet potato of the variety you wish to grow. The slips will be exact replicas of the parent plant. Selecting certified organic is also important because conventional store bought sweet potatoes may be treated with sprout inhibitors or pesticides that could impede this process.
When the sweet potato has grown plenty of new sprouts with green leaves, it’s time to cut your slips:
- Once sprouts have grown 5-6” long, you can cut them off the plant.
- Take the green sprouts and submerge them in water for 3-5 days.
- You may need to switch out the water a few times to keep it fresh.
- When the roots on your cuttings have grown a few inches long, they are ready to be planted in trays or directly in the garden.
The soil-grown slip route is the quickest way to produce slips. This is how commercial producers grow the slips that are shipped to you from seed companies. One mature sweet potato can grow 10-12 slips that can each be rooted into a new plant.
Propagation From Slips
The easiest way to grow sweet potatoes is by leaving the slip-starting to the experts. Order your slips in early spring and select the shipping date recommended for your zip code.
When they arrive, they may appear wilted, pale, or dried out. Don’t worry, this is a normal part of the shipping process! Just like bare root strawberry crowns, sweet potato slips are pretty resilient and will readily bounce back once planted. They may or may not have roots, but as long as the stems are still green, they should produce viable plants.
Begin by unbundling the slips and misting their roots with water. Keep them protected in the shade as you prepare your garden beds with the instructions below. The soil must be at least 60-65° before planting slips, so be sure to use a soil thermometer to check the temperature.
If it is still too cool, use a method below to hold your slips until the garden soil has warmed.
Sometimes the weather or life’s schedules are not in your favor. If you can’t plant your slips immediately upon arrival, you have two options for holding them until your garden beds are ready:
Wrap the bottom (root) end of the slips in damp paper towels, keeping the stems and leaves dry. Place them upright indoors at room temperature out of direct sunlight. Soak the slips in a jar of water for about 1 hour per day by submerging only the bottom third of the root-end beneath the water. Soaking for too long can lead to rot.
If you need to delay planting for a week or more, loosely plant the slips in a bundle in a container filled with an organic potting mix. There is no need to separate them into individual cells, but be sure to give them a bit of space to keep air flow between them.
Thoroughly water them in just as you would when planting a cutting in your nursery. Be sure the medium drains quickly, but stays consistently moist. Store them out of direct sunlight and watch them perk up in the days to come. When you’re ready to plant, you can lift the bundles out of the soil and gently separate their roots. This method can give you a nice head start with stronger slips at the time of planting.
Whichever method you choose, just be sure that the slips do not dry out or get exposed to intense conditions. They should be kept at room temperature, out of direct sunlight, and safe from wind or pesky rodents.
Planting sweet potatoes is a fun and intriguing garden project for children and adults alike. They are unique from other plants because they are grown from slips rather than from tubers (like true potatoes) or from seeds like other vegetables.
They require warm soil, so don’t plan to get these babies in the ground until late spring or early summer in northern climates. Usually the best time is at least one month after the last spring frost date. Use a soil probe to ensure that the soil temperature is above 60°F. You may want to heat the soil with black plastic for 2-3 weeks before planting. Alternatively, you can build raised beds that will warm faster in the spring.
How to Plant Slips
Begin by preparing a well-drained, loamy soil. Add 1-4” of compost to the top of your garden bed and use a broadfork to loosen the lower layers. Next, use your hands or the back of a garden tool to make 6” deep furrows about 36-42” apart.
Gently separate your sweet potato slips from each other, being careful not to break any established roots. Plant the slips with the bottom end (root end) facing downwards at least 4-6” into the soil. Be sure that all developing root nodes are buried.
If your soil is not deep or loose enough, you can lay the slips on their side with at least 3-4” of the slip submerged in the soil. The top growing point (and any leaves) should be above the soil surface.
If you are having a hard time figuring out which end of the slip is the root end, look for the thicker point of the stem with nub-like nodes. The top part of the slip will be thinner and may have young leaves emerging.
Slips should be planted 10-18” apart in rows 30-42” apart. Wider spacing typically leads to larger sweet potatoes, whereas closer spacing will create a larger quantity of medium-sized sweet potatoes.
The most critical part of plantain slips is ensuring that they are thoroughly watered in. These little stem cuttings are quite fragile and will wilt extremely quickly. Keep the soil consistently moist for at least the first week or two from planting. This is the most fragile time when slips need to be regularly monitored, especially during excessively hot or windy weather.
I always recommend that northern growers use row cover at the time of planting sweet potatoes. In fact, I keep row cover on top of sweet potatoes for most of the season on my New Hampshire client’s farms. This thin fabric works wonders for keeping them nice and warm, protecting them from wind, and conserving moisture, ultimately resulting in faster establishment.
Young plants need to be very carefully weeded or cultivated, but you have to be sure not to disrupt the developing slips. Once the runners begin to take off, weeding is typically not an issue because they are vigorous vines that will cover the bed.
Never trim off or remove runners. Unlike the runners of strawberries (which detract from yields), the plant actually needs these secondary roots for accumulating water and nutrients to send down to the developing roots.
As long as they get ample warmth and moisture during the growing season, sweet potatoes are fairly easy to grow. These tropical vines take off rather quickly once the slips are established. A few additional steps will ensure pest-free plants, an abundant harvest, and proper curing for long winter storage.
Sweet potatoes need full, direct sunlight for a least 6 hours per day, but preferably 8-10 hours. Plant them in the most open, south-facing part of your garden away from any trees or structures that may cast shade on the bed. Without enough sunlight, they will have paler leaves and lower yields of the coveted orange roots. However, if you are in an extremely dry or hot climate, partial afternoon shade can be beneficial for these vining herbaceous plants.
At the time of planting, slips are extraordinarily thirsty. The fragile stem cuttings can wilt and dry out very quickly, especially in extra sunny or dry weather. But once they are established, the plants are moderately drought tolerant.
They prefer an even, consistent moisture of about 1 inch of water per week. Use drip irrigation, soaker hoses, or sprinklers to keep the area moist.
When the plants are thirsty, they will tell you by wilting or drooping. Don’t panic- they bounce back quickly once their thirst is quenched with a deep, even watering. Avoid overwatering or growing these plants in heavy, water-logged soils, as this can rot the roots.
In the final 3-4 weeks before harvest, stop watering your sweet potatoes to prevent the roots from splitting.
Like many of our annual garden vegetables, sweet potatoes are a bit persnickety about their soil. The more loamy, well-drained, sandy, and warm the soil is, the happier they’ll be. Amend their beds with generous amounts of organic matter like peat moss, chipped leaves, or mild compost (don’t use anything high in nitrogen or mixed with manure).
You can also use sand to create that easy-draining soil texture that these roots crave. The soi should be loosened at least 8-10” deep. Raised beds tend to be best for drainage and warming purposes.
Try to achieve a soil pH around 6.5. Though they will tolerate some clay soils, avoid planting sweet potatoes in cold, heavy or compacted soils that don’t drain well. This will only lead to rotting and poor yields.
Sweet potatoes can be grown in USDA zones 5-11 as long as you have a minimum of 120 frost-free days for them to reach maturity. In northern zones, row cover (frost protection blankets), deep mulch, and greenhouses are a sweet potato gardener’s best friend. There are also quicker maturing varieties available for cold-climate growers that we will explore below.
Their ideal ambient temperature is between 75° and 95°F. These tropical roots really like it hot! However, if they are thoroughly established, they can tolerate down to about 45-50°F. A few days of temperatures below 40°F can significantly harm sweet potato vines or even kill them.
In the spring, the slips are even more sensitive to cold. It’s best to wait to plant until the soil is a minimum of 60°F and 2-4 weeks have passed since the final spring frost date.
Do not fertilize sweet potatoes at the time of planting. They actually prefer less fertile soils to thrive. In fact, too much nitrogen can lead to an overgrowth of above-ground foliage and skinny elongated roots below the surface.
If your soil is rich in organic matter or you incorporate compost before planting, there is typically no need to fertilize planting beds.
Sweet potatoes don’t typically require much maintenance aside from regular weeding and watering. Fortunately, the vigorous vines tend to keep weeds suppressed very well.
Pruning the vines sometimes is helpful when their vines start to overgrow your garden beds. Excessive foliage could lead to leggy, thin root harvests. Use scissors or pruners to cut off damaged, diseased, or extra lengthy vines. Cut just about the leaf nodes to encourage bushier growth instead of more rambling.
Sweet potatoes should be dug in the fall before the first frost, ideally when soil temperatures are still around 50°F. If you don’t catch them before a frost, harvest roots immediately after because frost damage can travel down from the foliage and significantly shorten the storage time.
Use a mower or hand clippers to cut back the vines before harvesting. Then, use a broadfork or spading fork to gently lift roots from the ground. The skins will be fragile at first, so it is important to handle them carefully and try to avoid scratching them.
Like winter squash, sweet potatoes need to be cured to improve their flavor and sweetness while toughening the skins for storage. Before curing, gently brush off excess soil from the tubers. Avoid washing or getting them wet as this could lead to rot.
Cure their roots for 4-7 days in a warm, dark, aerated area that is around 85°F and 85% humidity. A covered dark area of your kitchen, greenhouse, or outdoor patio should suffice. Be sure that they are spread out on tables or mesh in a single layer and use fans to keep the space well-ventilated.
After curing, roots can be stored in a cool, dark place at about 60°F. A root cellar, garage, or pantry often work great. For the highest sugar content and best flavor, it’s best to wait about 3-4 weeks after curing and storage to begin eating them. When properly cured, the roots can store for 6-7 months or longer.
There are over 400 unique varieties of sweet potatoes that can be grown in your garden, most of which you’ve never seen in stores. Many sweet potatoes come from far-stretched lands of Japan, Hawaii, Peru, and ancient Aztec settlements, whereas others have been bred in North Carolina and Louisiana.
Choosing the best variety for your garden comes down to the length of your growing season, your climate, and your flavor or aesthetic preferences. Here are a handful of our favorites:
- ‘Covington’: The classic well-adapted orange sweet potato, ‘Covington’ has blush-to-copper colored skin and a vibrant orange flesh. They mature in just 90 days and produce a uniform, easy harvest.
- ‘Beauregard’: Another classic commercial orange sweet potato, this variety is high-yielding, crack-resistant, and very reliable. 100 days.
- ‘Murasaki’: Known for its unique dry texture and nuanced, complex flavor profile, this purple-skinned sweet potato has a white flesh. It is best grown only in warmer regions due to its longer days to maturity (105 days) and inability to reach full size in cold weather.
- ‘Red Japanese’: With a super sweet, dry white flesh and burgundy to magenta skin, this Japanese sweet potato thrives in the south, but can also be grown in the north. Vines are exceptionally disease resistant and take about 95 days to mature.
- ‘Speckled Purple’: With flecked plum-colored flesh and a nutty, mild flavor, these creamy purple sweet potatoes are stunners in roasts and sautes.
Unlike Solanaceous potatoes, sweet potatoes generally have very few insect pests. A few beetles may cause some aesthetic damage to the foliage, but foliar damage typically does not cause major issues. However, wireworms, weevils or scurf can damage the roots and shorten storage capacity.
The most common pest is the sweet potato flea beetle, which is about 1.5 mm long, oval-shaped, and black with a reddish or bronze hue. They eat grooves in the leaves and cause necrotic (brown or dead) regions on the foliage. The white cylindrical larvae can crawl down and cause scars or tunnels in the roots.
The injury from these flea beetles is mostly cosmetic, but it can be prevented by keeping weeds under control and planting resistant varieties like ‘Centennial’ or ‘Jewel’.
The same blue-green beetles that you can find on your regular potatoes will also attack sweet potatoes. You’ll catch them feeding on the foliage and even defoliating whole plants if they get out of control. The easiest way to keep their populations down is by holding a bucket of soapy water beneath the plants and knocking them off the leaves to drown in the bucket.
You can also use floating row covers to exclude them or release parasitic nematodes from a biocontrol resource. Fortunately, these pests mostly hang out in the Eastern U.S. and are not a major issue in the West.
These annoying tiny yellowish-orange worms burrow cylindrical holes in sweet potatoes while they are in the ground. They tend to be the most problematic in areas where grass or corn were previously grown.
The easiest way to prevent wireworm damage is to avoid planting sweet potatoes in newly established beds, maintain a good crop rotation, and use bait stations (cups of corn or wheat flour submerged in soil) to monitor populations.
The most major pest of sweet potatoes tends to hang out only in the Carolinas. These ant-like beetles are about ¼ inch long and metallic black to dark blue, with bright orange legs. The white larve feed on exposed plants and put scars, tunnels, or holes in the roots, damaging the crop.
The best prevention is to “hill up” your sweet potatoes the way you would with normal potatoes. Be sure that no roots are exposed above ground. You should also destroy crop debris at the end of each season and alternate with other crop rotations. Neem oil or horticultural oil may also be helpful when applied at the base of the plants.
Scurf is a soil borne fungus called Monilochaetes infuscans that causes unsightly blackish-brown lesions on the skins on your sweet potatoes. The disease won’t necessarily ruin your harvest, but it will cause the roots to dry out more quickly in storage and not last as long through the winter.
Poor weed control (especially with morning glory family weeds) is the primary means of spreading scurf. It can also overwinter on planting material that isn’t removed from the garden at the end of the season. Maintaining clean, weed-free beds and purchasing certified disease-free slips are the best means of preventing scurf.
Sweet potatoes are most coveted for their delectably smooth, creamy cooked roots with high sugar content. They can be used in fries, chips, pies, roasts, sautes, scrambles, and a wide range of other sweet or savory dishes. They pair extremely well with a range of cuisines and seasonings, making them one of the most adaptable root vegetables in the kitchen.
They can be cooked with or without their skins, however the highest Vitamin A and trace mineral contents are found in the copper-orange skin.
The leaves of this plant are also edible. Their greens are sometimes used as a salad green in the hottest months of southern summers when no other fresh greens have made it.
Frequently Asked Questions
Can I grow them from an existing sweet potato?
Although you can plant a whole sweet potato in the ground, it is more common to use a sweet potato as the starter tuber for “slipping” to grow lots of baby plants. Submerge the bottom of the plant in water to encourage it to sprout. Once they are about 5 “ long, sprouts and leaves can be harvested from the mother sweet potato to be planted as “slips”, which are root cuttings that will grow into new plants.
What month do you plant sweet potatoes?
Sweet potatoes are heat-loving plants that are very vulnerable to cold temperatures. They are typically planted in late spring or early summer at least 3-4 weeks after the last frost in your growing zone. In most regions of the U.S. the ideal time is March through June.
How many sweet potatoes do you get from one plant?
Depending on the variety, a single plant can yield 5 to 10 medium-sized sweet potatoes. Closer spacing will yield larger quantities of smaller tubers, whereas wide spacing will yield fewer amounts of extra large sweet potatoes.
Are sweet potatoes easy to grow?
Sweet potatoes are fairly easy to grow as long as the soil is thoroughly loosened and well-drained, and they receive plenty of water at the time of establishment. The most critical period for growing success is during the first 1-2 weeks after planting the slips in the garden. Be sure that slips receive ample water, weeding, and protection from cold temperatures below 50°F.
The lovely sweet potato vine is a southern classic that can also be grown in northern gardens with the aid of row cover, mulch, and short-season varieties. Whether you like them mashed, fried, roasted, or pureed, sweet potatoes are a delectable autumn-harvested treat that will nourish you through the winter and spring.
They come in a vast diversity of colors and flavors that are unavailable in stores. With a little preparation and some extra space in the garden, you can harvest these nutrient-dense roots in great abundance.