Growing Sweet Potatoes

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growing sweet potatoes in the garden

Sweet potato plants flourish in warm weather, providing attractive ground cover while the sweet potatoes grow.

Unlike regular potatoes, which grow best when the soil is cool, sweet potatoes like it hot! They are tropical plants that are very sensitive to cold weather. In warm climates, many gardeners plant sweet potatoes about a month after the last spring frost, when both the air and soil are dependably warm. The plants produce lush vines that make a pretty ground cover, so they are a great crop for beds that adjoin areas that are difficult or tiresome to mow.

Soil, Planting, and Care

Sweet potato plants may need to be covered for a day or so if they wilt in the heat.

Shade plants if they wilt too much after planting them in the heat. A clay pot turned over the plant will do.

Sweet potatoes prefer a loamy, well-drained soil that is not too rich. Ideally the pH is between 5.8 and 6.2, although they will tolerate a more acid pH to 5.0. Before planting, mix in a 1-inch layer of compost and thoroughly dampen the bed. In heavy clay, grow them in raised beds amended with compost and sand; potatoes in clay are sometimes thinner and oddly shaped. Good root development depends on there being plenty of air space in the soil (good aeration). They are the ideal crop for areas with sandy soil.

Sweet potatoes are so willing to grow that plants accidentally dropped on the ground will take off and grow if the soil they land on is warm and moist. Plant sweet potatoes about 12 to 18 inches apart, and allow 3 feet between rows so the vines will have plenty of room to run. When setting out sweet potatoes in very hot, sunny weather, cover the plants with upturned flower pots for 3 days after planting to shield them from baking sun.

In the North, it’s a good idea to cover the soil with black plastic or black fabric mulch about 3 weeks before planting to warm the soil.

Give your sweet potato plants lots of room to roam.

Sweet potatoes produce long vines that need plenty of space to grow.

Sweet potato vines will soon cover a large area. Thoroughly weed your sweet potatoes 2 weeks after planting by pulling them gently; if possible avoid deep digging with a hoe or other tool that disturbs the feeder roots that quickly spread throughout the bed. These give rise to your sweet potatoes. Water weekly. Water is especially important as plants grow and roots spread.

Historically, sweet potatoes have been a poor soil crop that produces a decent harvest in imperfect soil, but will do much better with a little fertilizer. About 2 weeks after planting, feed plants with a balanced organic or timed-release fertilizer that contains potassium (the third number on the fertilizer label), such as 5-10-10. Use about 2 cups 5-10-10 per 30 square feet (a 10-foot row). Gently scratch the fertilizer into the soil surface. Then mulch over the soil with an inch of grass clippings or another biodegradable mulch. Continue weeding and adding more mulch for another month. After that, sweet potatoes can usually fend for themselves, though they do benefit from weekly deep watering during serious droughts.

Or, simply feed with a liquid plant food, like Bonnie Herb & Vegetable Plant Food. Apply at planting, then every couple of weeks as the plants root and grow.

Troubleshooting

Mulch sweet potato plants to help reduce water loss in hot regions.

In climates where summer is hot, mulching before the vines get too long will help keep your sweet potato patch moist and weed-free.

Deer love to nibble tender sweet potato leaves, so you may need to deter them with floating row covers. Japanese beetles and other leaf-eating insects may cause light damage, but sweet potatoes are so vigorous that they usually outgrow foliage pest problems. More troublesome are pests that might attack the tubers. In Florida and some other southern states, sweet potato weevils are a big problem, often ruining the harvest. Wireworms and nematodes can also attack sweet potatoes.

You may have heard of a fungus disease called scurf that is very destructive to sweet potatoes. It is soil borne and nearly impossible to get rid of once the soil is infested. Fortunately, you can avoid scurf by always planting certified, disease-free plants such as those sold by Bonnie.

In late summer, sweet potatoes often produce flowers that resemble those of morning glory, a close botanical cousin.

Harvest and Storage

Sweet potatoes need to cure to be the sweetest. Clean them dry, not wet.

After harvesting, brush soil from potatoes but don’t wash them. Sweet potatoes that cure for several weeks in cool storage will taste the sweetest.

Compared to other sweet potatoes, Beauregard matures early, about 90 days after planting. They are usually ready to harvest just as the ends of the vines begin to turn yellow, or just before frost in the North. To avoid injuring tubers, find the primary crown of the plant you want to dig, and then use a digging fork to loosen an 18-inch wide circle around the plant. Pull up the crown and use your hands to gather your sweet potatoes. To make digging easier and get the vines out of your way, you can cut some of them away before digging. Harvest before frost because cool temperatures can reduce the quality of the potatoes and their ability to keep.

The best, sweetest sweet potatoes are baked without aluminum around them.

Don’t wrap sweet potatoes in aluminum foil when cooking because that causes them to steam. If you bake them without wrapping, they will caramelize.

Sweet potatoes are not very sweet when first dug, but they are fine for sweetened pies or casseroles. They need a period to sit and “cure” to bring out their sweetness. Shake off soil, and then lay the unwashed sweet potatoes in a warm (80°F to 90°F), well-ventilated place for about 10 days. A shaded table outdoors and out of the rain works well. As the sweet potatoes cure, any scratches in the skins should heal, and the flesh inside will become even sweeter and more nutritious. This is very important, as fresh, uncured potatoes do not bake as well. After 10 days, move your cured tubers to any spot that stays cool and dry, but do not refrigerate or store below 50°F. Cured sweet potatoes will keep for up to 6 months when stored at around 60°F with high humidity; a basement is ideal, though an air-conditioned storage room or pantry will do, too.

FAQs

How long a growing season do I need to raise sweet potatoes?

Sweet potatoes are a tropical vine so they need several months of warm weather. Mulching planting beds with black plastic warms soil – perfect for giving plants a touch of the tropics and reducing weeds. Many of today’s varieties are better adapted to growing in shorter seasons than varieties were years ago.

Sweet potato vines are growing beyond the garden area. Can I trim them to keep them in bounds?

The vines of sweet potatoes tend to ramble far and wide, which is why many home gardeners don’t raise them. If vines are wandering out of bounds, try turning them back into the vegetable garden. It’s best not to trim vines; they help feed the potatoes.

When can I start digging sweet potatoes?

You can harvest sweet potatoes as soon as they reach a usable size, which takes at least three months. Harvest a few tubers to see if they’re large enough before digging the entire patch. Plan to dig all sweet potatoes before frost.

How do I harvest sweet potatoes?

Clip vines and save them for the compost pile. Use a garden fork to unearth tubers, starting at the edge of the patch and working your way in toward vines. Sweet potatoes tend to grow near the surface. Dig carefully; tubers bruise easily at this point. Curing is what gives them a hardened skin. If you damage any sweet potatoes during digging, send them straight to the kitchen – they won’t cure or store. Use them as soon as possible.

My sweet potatoes are long and thin. Is there something wrong with my soil?

Too much nitrogen in the soil causes long, thin roots. When planting next season, don’t improve soil in your sweet potato patch with anything that might add nitrogen (such as compost), and don’t fertilize.

Frost is predicted and I haven’t harvested all the sweet potatoes. What should I do?

Because sweet potatoes are tropical, frost will harm vines and can also damage roots. If you absolutely cannot harvest all sweet potatoes before frost, mulch the patch heavily with straw or other cover.

119 thoughts on “Growing Sweet Potatoes

  1. Hi Mr. Danielle Bonnie this is my very first time trying to garden I love sweet potatoes and wont to try to grow them can I built a garden bed and if so what size should it be I have 9 baby plant and what kind of soil should I use.
    PS Mr. Danielle I would love other tips on growing other vegetables in flower pot.

    • Hi Cynthia,
      You are going to need enough room to plant the sweet potatoes about 12 inches apart, allowing 3 feet between rows so the vines can run. Sweet potatoes are not as picky about soil as other vegetables are, but if you are going work to build a raised bed, you may as well create a good soil bed – other veggies that you plant later will appreciate it. I usually do not build beds larger than 4 feet wide. That way noone has to step into to plant or harvest. There are many articles on raised beds in the Bonnie Plants library. This one has great advice for filling the raised bed. Container gardens…love it! Start with the right size pot and a good potting mix . These are great tips for Caring for Vegetables in Pots. Have a great harvest! – danielle, Bonnie Plants

  2. We are first time growers of sweet potatoes. Plants were given to us. How do you tell when they are ready to harvest?

    • Hello Trudy,
      It takes about 95 days after planting for the sweet potatoes to mature. They are usually ready to harvest when the tips of vines start to yellow – dig before the frost in the Northern areas. – danielle, Bonnie Plants

  3. Do I need a raised garden bed to plant the sweet potatoes in? I have a 20′ x 25′ garden plot at a community garden. The soil has been plowed twice and ’tilled twice and is very loose. I have completely covered the lot with professional grade landscaping fabric. I was hoping to plant the slips directly in the ground.

    • Hello Woody,
      You can plant the potato slips directly into the ground. Note that the vines will want to take root along the ground as they grow. – danielle, Bonnie Plants

  4. I was given three seedlings and was wondering if I can plant them with my tomatoes. The soil is great but I don’t want to crowd my tomato roots. Tomatoes are properly spaced and caged. If I decide to pot them, can I use regular potting soil or is something else recommended? Thank you!

    • Hello Maureen,
      You can plant sweet potatoes near your tomatoes, but sweet potato vines will run. It’s good to have 3 feet on either side of the sweet potatoes so the vines will have plenty of room. If you decide to pot them, a good potting mix is recommended. Use a large enough container to adequately space the sweet potatoes. The vines will run over the sides, and they can take root wherever they find a good spot :) – danielle, Bonnie Plants

  5. Do sweet potatoes need to stay away from tomatoes like other potatoes do? Can the sweet potatoes be planted in a raised bed where tomatoes grew the previous year?

    • Hello Liz,
      Sweet potatoes are not in the same family as tomatoes, peppers, eggplant, and potatoes. Yes, sweet potatoes can be planted in beds where tomatoes grew previously. – danielle, Bonnie Plants

  6. I purchased some Beauregard sweet potato plants from a local retail store and planted them into my raised bed. They seemed to be doing fine for a few weeks and now I’ve noticed that the leaves are starting to turn a dark red/puplish color. I’ve searched online for an answer but can’t seem to find one. Could you possibly give me some suggestions as to why this is happening?

    • Hello Rachel,
      Were the sweet potato vines fertilized prior to being planted? If not, it’s time to fertilize. Purpling leaves are a symptom of nutrient deficiencies. -danielle, Bonnie Plants

  7. I previously asked you a question about growing sweet potatoes in a jar as house plants. What I forgot to mention was, you fill the glass container with water. Anyway, this is what I was told to do if you wanted a beautiful easy to maintain house plant. Just sounds too easy???? Thanks much, Linda

  8. The rabbits have eaten our cauliflower and all I have left in a large bed are leeks. Will sweet potatoes grow in a bed with leeks?

    • Hi Deborah,
      The rabbits in my garden must have taken a break to nibble in yours :( Yes, sweet potatoes will grow in a bed with leeks, just give the sweet potato vines ample room to grow. – Danielle, Bonnie Plants

  9. How deep down do the tubers grow? Is a 6″ raised bed deep enough? I heva very rocky soil.

    • Hi Jon,
      Most raised beds are 12″ for sweet potatoes. Sweet potatoes can get large! You can try 6″, I do not like to discourage, but your sweet potato harvest may not be as large. – Danielle, Bonnie Plants

  10. Can I grow my slips (next year) indoors under lights and using a heat pad for about 30 days to get a head start in order to harvest in 65 days? If so, what size container should I use.
    Thank you so much for this site!
    Linda

    • Hi Linda,
      You will want to start sweet potato slips with a sweet potato! Mother Earth News has some step by step instructinos on doing this at home. – Danielle, Bonnie Plants

  11. Thank you for the great informantion Danielle. Will more than one potato grom from each slip that is planted??

  12. When growing sweet potatoes in large containers can you run them up a trellis?

    • Hi Janell,
      The extension system at Washington State even mentions a trellis for sweet potatoes in their gardening publications! I would love to see them growing – send a picture to the Bonnie Plants facebook when you get them growing :) – Danielle, Bonnie Plants

  13. I’m new to planting sweet potatoes in garden. I have a 4×6 foot raised bed. Is this large enough to plant sweet potatoes and if it is how many potatoes should I hope for at harvest.
    I just saw some Bonnie Beauregard Sweet Potatoes at Lowes and would love to plant.

    Thanks for info. Charlotte

    • Hello Charlotte,
      It is large enough – sweet potatoes are planted about a foot apart. Their vines will run for 6 feet, so expect the vines to run over and beyond the raised bed. You will find the vines will also take root and smaller potatoes can be dug there although you will dig the main harvest where the slips were planted. You can expect 5 – 15 pounds of sweet potatoes per 10 feet of row. Variation is due to soils, weather, and pest pressures. Take a peek at what other Bonnie Plants gardeners are saying about Beauregard Sweet Potatoes, here. – Danielle, Bonnie Plants

  14. Will sweet potatoes grow if planted in containers using potting soil or potting mix?

    • Hi Ann,
      You can successfully grow sweet potatoes in a container using a good potting mix. You will need a large container; space them about 12 inches apart. Sweet potaotes are vines so expect them to run 5 – 6 feet from the container. They will also want to root along the vine (where it touches ground). – Danielle, Bonnie Plants

  15. Can I use old truck tires to make a raised bed? If so how may plants do I put per tire? Tks, Hal

    • Hello Hal,
      Sweet potatoes are spaced about a foot apart – so it would depend on the size of the tire. They are vining plants so as they grow they will take root. They will not stay contained in the tire. They will need room to grow and spread! – Danielle, Bonnie Plants

  16. (MMMMMMM!) I love to eat white sweet potatoes. By the way, I’m from Mississippi. I would like to know when is the best time to plant (White Sweet Potatoes). What is the best method/time to plant these particular type of sweet potatoes.

    Thank You very much,
    Dianne from Mississippi :)

    • Hello Dianne,
      Yummy…I love all sweet potatoes…especially baked with one pat of butter and a scoop of vanilla ice cream :) Sweet potatoes are a tropical root crop so do not plant until all danger of cool weather is gone. They are grow throughout the warmest months….3 – 4 months. University of Mississippi Cooperative Extension has a great bulletin on growing sweet potatoes in your area. Happy Planting!
      -Danielle, Bonnie Plants

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