The sweet potato, Ipomoea batatas, is a large, starchy, sweet, tuberous root vegetable. Although widely believed to be from the potato family, sweet potatoes are actually from the morning glory family.
Sweet potatoes grow as a herbaceous perennial vine with long, tapered tuberous roots. The roots come in a variety of colors, ranging from beige, brown, yellow, orange, red, and purple.
The flesh of the root also has varying shades ranging from white, beige, yellow, orange, pink, red, and purple. But pale-colored sweet potatoes are less sweet than those with orange, or red flesh.
Sweet potato vines are hardy and will grow in zones 8 through 11 on the USDA plant hardiness zones.
They grow best at average temperatures of about 75°F with 30-39 inches of annual rainfall.
Sweet potato vines like moderate moisture, but are sensitive to water-logging. Poorly drained growing medium will cause tuber rot and reduced growth in the plant.
Sweet potatoes can grow in a wide range of climatic conditions. Thus, they are ideal for widespread cultivation. All they need is well-drained, light to medium-textured soil at a pH of between 4.5 and 7.
However, they need soil treated with lime in areas where aluminum toxicity might be an issue. They are highly sensitive to aluminum and will die if the soil is not treated with lime.
Here are notable characteristics of the sweet potato plant:
|Botanical Name||Ipomoea batatas|
|Common Name||Sweet potato, Yam|
|Plant Type||Many of the cultivars are perennial, but most people grow them as annual vegetables|
|Mature Size||Vines may spread up to 20 feet, with the tubers averaging between 4 and 6 inches long|
|Sun Exposure||Full sun to partial shade|
|Soil pH||4.5 to 7|
|Bloom Time||Between 3-4 months after planting|
|Flower Colors||White, Lavender|
|Hardiness||Zones 8 to 11|
|Native Areas||Tropical Americas|
Note: Many people in North America refer to sweet potatoes as “yams.” However, sweet potatoes are very distinct from yams. Yams (Oxalis tuberosa), also known as Oca in Polynesia, are an entirely different plant. They have brown, bark-like skin, and when cooked, have white starchy flesh.
How to Grow Sweet Potatoes in Containers
Typically, growing sweet potatoes requires a lot of space. But with a few planters and a bit of ingenuity, you can grow them in small spaces.
Here’s what you need to do to grow sweet potatoes in containers:
Step # 1: Select a Variety Suitable for Growing in Containers
Sweet potatoes usually grow in sprawling vines. They spread across the ground, developing roots where the vines meet the dirt. But if you have limited space, this will not do.
Thankfully, you can plant some varieties of the sweet potato in containers. All you have to do is ensure that you get the right cultivar and a big enough container.
Dwarf varieties with compact vines are the most ideal for potting. You can even train them to grow upwards using stakes and trellises.
The most popular container varieties include:
- Bush Porto Rico: This is a bush variety of copper-skinned potatoes with orange flesh. It takes about 110 days to reach full maturity. It’s also high yielding, making it ideal for small gardens and containers.
- Beauregard: A popular commercial variety with reddish skin and dark orange flesh. It takes about 100 days to reach full maturity.
- Georgia Jet: This is a variety ideal for shorter seasons. It matures within 90 days to produce red-skinned tubers with orange flesh.
- Centennial: This is popular because of its disease resistance and quick maturity. It grows to full maturity within 90 days.
- Vardaman: Another popular variety for small garden and container farmers. It’s a compact bush-type variety with golden skin and orange flesh.
- Patriot: This is an excellent option for organic gardens due to its pest resistance. It’s also known for its copper skin and orange flesh.
Keep in mind there are many more cultivars to choose from. Consult your local garden center, or seed and specialty catalog for more options.
Step # 2: Select the Right Container
Not all containers are created equal! This is the first rule when picking out a container to grow your sweet potatoes in.
Opt for containers made explicitly for potato growing. These work best and are cheaper compared to plastic or ceramic options.
If unavailable, you can repurpose any large containers. At least two cubic feet in volume is necessary for sweet potato tubers to flourish.
Whiskey barrels and large clay containers also make excellent potato platers. However, shy away from plastic or metal containers.
Ensure whatever planter you choose has enough holes at the bottom. Proper root aeration and drainage is critical when growing sweet potatoes. But don’t make the holes so big that the planting medium falls out.
Alternatively, you can go for a potato growing bag. These are specially designed to provide root aeration and adequate drainage. They also make the harvesting process easier once the potatoes mature. Simply lift the bag and dump the contents into a wheelbarrow.
Step # 3: Select the right location
Location is key in ensuring the success of your potted sweet potatoes. Pick a spot with southern exposure, so the sweet potatoes get full sun.
Your spot should also be relatively warm to keep the growing sweet potato slips healthy. Remember, they are highly sensitive to frost and will die if exposed.
Ensure the temperature at the spot you pick never drops below 60°F.
Also, keep in mind that the planters get quite heavy. The area should be able to support this extra weight. Ideally, an area where you won’t have to move the containers often.
Step # 4: Use the right soil
Sweet potato plants prefer moist soil, but don’t like to sit in water. A good planting mix is compulsory when growing sweet potato slips in a container.
You can amend a growing medium with compost, sand, and high potash fertilizer to achieve an ideal blend.
How to Propagate Sweet Potato Slips
Sweet potatoes can be propagated either through sexual or asexual means.
However, sexual propagation – through actual sweet potato seeds, is only of interest to plant breeders and geneticists.
For farmers and gardeners, asexual reproduction is the most common method to propagate sweet potatoes.
Plants with healthy foliage are ideal for this method of propagation.
1. Propagation from Stem Cuttings
Propagation by stem cuttings is the quickest, most economical method of vine reproduction.
To reproduce sweet potatoes using this method, take cuttings from the tips of young stems. The cuttings should be between 8 – 16 inches, with three to five growth buds.
Plant these sweet potato cuttings at a slant. And leave about 1 to 1.5 inches above the ground.
Note: Only take the cuttings when you are ready to plant. Keep them in the shade until the moment you plant them. The cuttings are very delicate, and will not keep for long.
Propagation using cuttings is only feasible if you have vines growing all year round. This makes them less ideal for gardeners who grow their crops annually in containers or small gardens.
Thankfully, this is where the second sweet potato propagation method comes in!
2. Propagation from Slips
If you don’t have access to sweet potato plants with enough leafy growth for cuttings, slips are the way to go.
Here, you can either propagate your own or buy ready to plant slips.
If you decide to buy, do so when it’s warm enough (60°F – 65°F) to plant sprouting sweet potato slips immediately. Young slips are delicate and don’t like cold weather or frost.
To propagate sweet potato slips, you can use the tubers you already have at hand. Whether they’re from the grocery store or leftover from last year’s crop.
Be sure to pick ones that are blemish and disease-free to produce healthy slips.
A single sweet potato tuber can sprout several dozen slips. You might need a few tubers depending on how many slips you wish to produce.
Once you’ve selected your star tubers, here’s what you need to do to start slips for planting:
- Stick toothpicks into the top third of your potato.
- Set the tuber over a jar of water, submerging the bottom two-thirds.
- Place the jar in a warm, sunny spot.
- Change the water every couple of days, always ensuring the bottom of the tuber is underwater. Usually, it takes at least two weeks before the slips emerge from the top of the tuber. Plan ahead and start your slips a few weeks before the planting date.
Note: It’s better to use distilled water when producing slips. Heavily chlorinated tap water might prevent the tubers from sprouting.
Preparing Your Sweet Potato Slips for Planting
When the slips are six to eight inches long, they are ready for transplanting into the containers. But first, you have to separate them into individual slips.
To do this, you should:
- Carefully twist them off the slips to separate them from the tuber. The slips may have already developed some rudimentary root structures. Be careful not to damage them.
- Place the sweet potato slips in a bowl with the bottoms submerged in water. This will encourage further root development and should take about a week.
- When the roots grow to about an inch long, you can transplant the slips to the containers.
Note: Like with any other seedlings, you need to harden off your sweet potato slips. You can do this by gradually introducing the slips to outdoor conditions. Do this one to two weeks before breaking them off the mother sweet potato.
How to Plant Sweet Potato Slips
The secret to an excellent sweet potato crop is loose, well-drained soil. Amend your planting medium with plenty of compost to achieve a well-aerated mix.
Sweet potatoes are light feeders, but they do appreciate phosphorus and potassium. Work in a balanced organic fertilizer into your medium before planting your slips.
However, avoid high nitrogen fertilizers. These encourage foliage growth at the expense of the tubers.
Follow these simple steps to get your potting soil ready for your sweet potatoes:
- Fill your container with a high-quality potting mix to about an inch below the rim. Remember not to pack the soil in; tubers grow big in loose soil.
- Mix in a slow releasing fertilizer into your potting mix to ensure even distribution.
- Make a hole in the medium deep enough to cover the roots of the slips. Place one or two slips in the hole and cover up to the top leaves.
- Pat down the soil around the slips to get rid of any air pockets around the roots.
- Thoroughly water the sweet potato slips and add more planting medium if the mix settles and drops too low.
- Place your potted potatoes in a sunny spot, and ensure the growing medium stays moist, but not wet. Check the moisture by sticking your finger into the soil, down to the second knuckle. If the soil feels dry, water the plants, but if it’s moist at your fingertips, you can wait a day or two.
Tip: Occasionally, some sweet potatoes might peek through to the top of the soil. If you notice this, cover them with a bit of dirt to keep them out of direct sunlight.
And, just like with other potatoes, do not eat them if they turn green.
Sweet potatoes mature after about 90 to 170 days. Account for this when planting to prevent your crop from getting caught in the first fall frost. Cold temperatures, even in maturity, could damage your yields.
Note: Sweet potato vines are extremely frost-sensitive. Plant them at least 3 to 4 weeks after the last frost, when it’s nice and warm.
How to Care for Your Sweet Potatoes in Cold Weather
Sweet potato vines die in cold weather. But with proper care, they can survive the chilly winter and sprout again come spring.
Here’s what you need to do to protect your plants from the cold:
Place your sweet potatoes against a sunny, south-facing wall in a wind-sheltered area.
Areas with southern exposures typically receive more sunlight, especially during winter. And as we know, sweet potatoes like full sun.
Also, wind protection is vital in regulating the temperature and preventing freeze injury.
In the event of frost in your area, water your sweet potato plants and cover them with plastic sheeting. You can do this by suspending the plastic sheet over the vines using stakes. You can also weigh down the plastic sheeting around the edges with rocks to keep out the cold air.
The plastic sheets create a temporary greenhouse effect around your sweet potatoes, shielding them from the cold.
In addition, you can also use outdoor-rated lamps to help warm up your sweet potatoes.
Replanting in the Spring
Prepare the planters in the warm spring weather after any chance of frost has passed.
Mix in a generous amount of compost with your planting medium and ensure it’s mixed well.
Follow the steps to propagate sweet potato slips from above. When the slips are ready, plant them in the containers.
Remember to confirm that the soil temperature is at least 60˚F before planting a sweet potato. Usually, the soil temperature gets to 60°F after the air temperature has been above 65°F for a few weeks.
How to Harvest and Store Potted Sweet Potatoes
You will know your sweet potatoes are ready for harvest when the leaves and vines start to turn yellow. This usually takes about 3 to 4 months, depending on the cultivar.
But the longer you leave the crops in the pots, the higher the yield and vitamin content. Just be sure not to leave them out long after the vines die, or first fall frost sets in. Otherwise, the tubers will start to rot.
If you like to eat the leaves as greens, you can pick them in moderation throughout. Picking a few leaves might even help boost yields.
The tubers grow bigger when you keep the vines from growing too big. This way, the sweet potato plant spends less energy on growing leaves and more on the roots.
Once you are ready to harvest:
- Use a garden fork to loosen the soil around the plant (about 18 inches diameter), so you don’t injure the tubers.
- Pull up the crown, and use your hands to dig up the tubers. Sweet potato tubers bruise easily, so it’s better to use your hands.
- Shake off any excess dirt, but DO NOT wash the tubers.
- Set aside any damaged potatoes to be eaten first.
Once you’ve harvested all your sweet potatoes, you need to cure them. The curing process helps the potato flesh sweeten up. It also heals the small scratches and bruises on the skin for long term storage.
To cure your potatoes, keep them in a warm place (about 80˚F) at high humidity (about 90%) for two weeks. A table placed in a shaded area will work.
For best results, ensure that the potatoes are not touching during the curing process.
After the curing process, discard any bruised potatoes. Wrap the rest individually in newspapers and pack them carefully in a basket or wooden box.
Store the cured potatoes in cool, dark places between 55˚F to 60˚F.
A root cellar, basement, or any other such place should work fine.
Be gentle when handling the potatoes, like when moving, them to and from storage.
Cured potatoes can keep for up to 6 months.
Pest and Disease Control in Potted Sweet Potato Plants
The sweet potato plant is a hardy plant that can withstand most conditions. Well, other than frost and waterlogging.
However, there are also a few pests and diseases your plants might be susceptible to.
Thankfully, you can avoid these by using disease-resistant cultivars and certified disease-free slips.
Other common pests and diseases you might encounter are:
I. Sweet Potato Weevils
Sweet potato weevils puncture the vines and tubers to lay their eggs. The larvae tunnel and feed on the tubers while mature weevils mostly attack the vines and leaves.
You can identify these weevils by their dark blue heads and wings and reddish bodies.
They can cause significant damage to your crops because they spread foot rot. And since they multiply quickly, they can be hard to control and eliminate.
The best course of action if you notice weevils, is to destroy infected plants and their roots. Alternatively, you can prevent infestation by using certified disease-resistant slips when planting.
II. Fungal Diseases
Sweet potatoes can sometimes retain moisture under their foliage. The resulting warm and damp conditions are ideal for fungal diseases to grow and spread. These include diseases like:
- Black rot
- Dry rot
- Leaf mold
- Mottle necrosis
- Southern Blight
- Violet root rot
You can make your vines less conducive for fungal growth and infection by:
- Observing proper cultivation
- Planting healthy slips
- Using resistant cultivars
- Maintaining fleshy roots at 55 ˚F – 60˚F
Sweet potatoes are among the healthiest foods on the planet. They are full of essential vitamins and nutrients and are a great source of dietary fiber. And as with many foods, they are healthiest when grown organically.
But growing sweet potatoes, or any crop with limited spaces, can be a challenge. Even more so if you are growing the plants in containers.
But with the help of online resources like Gardening Channel, you need not worry. Here you can get all the gardening tips and tricks you will need to realize your gardening dreams.