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How to Successfully Grow Sweet Potatoes

How to Successfully Grow Sweet Potatoes

While sweet potatoes may not be the first crop that comes to mind for the northern half of North America, their potential for success in these regions is often underestimated. Despite their reputation for high heat requirements and long growing seasons, sweet potatoes can thrive in the north, offering a unique and rewarding addition to your vegetable garden.

Contrary to a common misconception, growing a healthy crop of sweet potatoes is not impossible in the north. Rather, it’sIt’s quite simple, and I’ve been able to do so successfully in my zone 5b garden, year after year. With a bit of know-how and the right conditions, you, too, can enjoy the satisfaction of growing your own sweet potatoes.

In this post, I share exactly what I do to grow sweet potatoes. I walk you through my method for growing them, explaining what a slip is, how to grow your own, and how to successfully transplant them to your garden. It couldn’t be simpler, and I can’t wait to share my process with you!

Why is growing potatoes different from growing sweet potatoes?

Potatoes are members of the Solanaceae family and are closely related to tomatoes and peppers. On the other hand, sweet potatoes are members of the Convolvulaceae family and are closely related to morning glory flowers. While potatoes are grown from tubers planted deep under the soil line, sweet potatoes grow from sweet potato vines or slips.

How to Successfully Grow Sweet Potatoes

Flowers growing on a sweet potato vine resemble Morning Glory flowers.

What is a slip?

A slip is another word for a sweet potato vine. To grow a crop of sweet potatoes, we first need to grow a few slips.

How to grow your own slips

Growing your own slips is easier than you may think! It requires very little attention and a bit of patience. There are two ways to grow your slips, and I will discuss each method and share my favourite at the end.

How to Successfully Grow Sweet Potatoes

One sweet potato will produce countless slips!

Method #1 for growing sweet potato slips

This method requires a glass of water, toothpicks, and an organic, store-bought sweet potato. You may either cut your sweet potato in half or leave it whole. If you leave it whole, push three toothpicks into the sweet potato at the halfway mark, spaced evenly apart. The toothpicks should encircle the sweet potato. Submerge the sweet potato in the glass of water. The toothpicks will hold it up, suspending it. Leave the sweet potato in the glass, topping up the water as needed. With time, the sweet potato will start to grow slips all over, some under the water and some above the water.

If you cut the sweet potato in half, you will need two glasses of water and six toothpicks. Push three toothpicks into each half of the sweet potato closer to the cut end, ensuring at least ½ an inch of the sweet potato is submerged under the water. Leave each half to develop slips, ensuring to top up the water as needed. Over time, each half will start to grow slips.

How to Successfully Grow Sweet Potatoes

Growing sweet potato slips in a glass of water.

Method #2 for growing sweet potato slips

How to Successfully Grow Sweet Potatoes

Sweet potato slips will develop on all sides of the tuber.

This is the method that I follow, and I find it to be the easiest. For this, you will need a whole sweet potato and some sort of plastic produce tray, like a mushroom container from the grocery store or a small seed tray, to comfortably fit a sweet potato tuber lying down. (I tend to keep these produce containers for reasons such as this one!) Once you’ve chosen your container and tested if the sweet potato fits, fill it about 2 inches deep with seed starting mix. Lay your sweet potato tuber in the soil buried halfway. Water the soil well, and leave the sweet potato until it begins to grow slips. Check and water the soil from time to time, ensuring it doesn’t fully dry yet isn’t sopping wet.

How to Successfully Grow Sweet Potatoes

You can set your tubers under grow lights or in a bright window.

*Note: Why choose organic over conventional sweet potatoes? The reason is very simple. Conventional sweet potatoes may have been sprayed with growth or sprouting inhibitors to extend their shelf life. If you want your sweet potato tuber to grow slips, a growth inhibitor would prevent that from happening.

What to do once the sweet potatoes have grown slips

Now that your sweet potato tuber is beginning to grow slips, what do you do next? You will need to remove the slips and either root them or pot them up. This is quite simple, and for me, satisfying. You can wait until the slips are at least 6 to 8 inches long before removing them. That length makes them easier to handle.

Starting with sweet potatoes set in a glass of water. Any slips growing from under the water will naturally have developed their own roots and can be removed by carefully twisting off the slip from the tuber and potting directly into a 4-inch pot. If the slip is growing above the water, you will need to remove the slip and root it in a glass of water. Once roots develop, pot it up into a 4-inch pot. The remaining sweet potato can remain in the water as it will pump out more slips, giving you even more sweet potato plants! These tubers are major workhorses, so you won’t need many tubers to get started. Depending on your desired harvest size, you may only need 1 or 2 sweet potatoes. If you want to harvest bushels of sweet potatoes, consider starting more tubers.

How to Successfully Grow Sweet Potatoes

Sweet potato slip potted up into a square 4-inch pot.

The process is very similar to sweet potatoes growing in a tray of soil. Any slips growing from under the soil will naturally have roots. Gently pry off the slip and carefully pull it out of the soil, with accompanying roots, then pot it up into a 4-inch pot. If a slip grows on the tuber above the soil, pry it off and place it in a glass of water to grow roots. Then remove it and pot it up into a 4-inch pot.

Growing requirements for Sweet Potatoes

Sweet potatoes require a long, warm growing season. Choose a full sun location with a minimum of 6 to 8 hours of full afternoon sun. If you are in the northern hemisphere, grow your sweet potatoes in a raised bed or a grow bag. This will help to keep the soil warm, and spring soil will thaw and heat much earlier in the season than in an inground location.

Sweet potatoes thrive in the southern hemisphere and can be grown in the ground or a raised bed. The season is much longer there, and your sweet potato vines will thrive!

Be sure to provide well-draining soil, as standing water will cause the roots and tubers to rot.

How to transplant slips into your garden bed

Your slips will continue to grow after being potted up and start producing gorgeous vines. At full maturity, they may reach 20 feet! Transplant slips to the garden after all risk of frost has passed.

Plant your sweet potato slips spaced 12 inches apart. It is recommended to space the rows at least 36 inches apart, but I’ve been successful growing them 12 inches apart in all directions. This is what works in my garden, and I grow them in raised beds. However, to grow larger sweet potato tubers, consider spacing your rows further apart and see what works best in your garden.

How to Successfully Grow Sweet Potatoes

Sweet potatoes growing in the garden.

Sweet potato vines will sprawl and develop beautiful flowers resembling morning glories. I tend to leave mine to sprawl over the ground, but feel free to create a trellis or support.

Be sure to water the soil well after planting and maintain consistent watering until vines begin to grow and establish.

When and how to harvest sweet potato tubers

Your sweet potatoes will be ready for harvest before the first frost date in the fall. Watch the forecast and be sure to harvest before the first expected frost. Vines are quite tender and will perish immediately if they encounter frost, potentially affecting the tubers.

To harvest, follow the vines back to where they begin at the base of the plant. Trimming the vines will make things easier, as the vines will be long and abundant by this point, and it may be difficult to identify one plant from the other. In addition, anywhere the vines were in contact with the soil, roots and potentially small tubers will form. Begin by pulling up the rooted vines, then follow backwards to the base. Gently pull up the plant, and the tubers will come up in a clutch. Be careful not to damage the tubers, as they are young and delicate. Snip the vines off the tubers at the tips and carefully lay them into a box or a bucket. Check the soil for stray tubers after all the vines have been pulled up. Vines can be composted.

How to Successfully Grow Sweet Potatoes

A harvest of homegrown sweet potatoes.

Storing sweet potato tubers

Before storing your sweet potato tubers for the winter, it is important to cure them. This will help to toughen their skins and will also improve their flavour. To cure them, brush off any loose soil and lay the tubers on a table or work surface in a warm location out of direct sunlight for at least a week. After curing, store the tubers in a cool room, out of direct sunlight. Choose a wooden bushel basket, wicker basket or wooden box. If the room temperature drops to freezing, it will damage the tubers. Instead, choose a location above 10C/50F, and your sweet potatoes will store easily over the winter.

It’s not too late to start your sweet potato tubers. Grab an organic sweet potato from the grocery store and start yours today.

Will you grow sweet potatoes in your garden this year?

Happy Gardening!

1 Comment

  1. Anna

    This is all fascinating! I’d live to try growing sweet potatoes. What would you say should be the minimum soil depth in a raised bed?

    Thanks so much!
    Anna

    Reply

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Julia Dimakos

Hi, I'm Julia from Mono, Ontario, Canada. I began my gardening adventure after having children. Since then, my interest grew into a passion. I love growing vegetables, herbs, flowers, fruit and medicinal herbs. I'm here to show you that growing your own food is not difficult and in fact can be simple.