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Planting, Growing, and Harvesting Sweet Potatoes
A few sweet potato plants can produce a generous harvest! This nutritious, sweet-tasting root vegetable is heat-tolerant and pest-resistant. Here is everything you need to know about growing sweet potatoes.
Though commonly grown in the South because they require warm weather, northern regions can have success, too. See our advice on which varieties to choose below.
About Sweet Potatoes
The sweet potato is a tropical plant and is actually a member of the Morning Glory family. Compare a sweet potato vine鈥檚 foliage and flowers to those of morning glory, and you鈥檒l see the family resemblance! Despite their name, they are not related to potatoes, which are in the nightshade family. Another difference between sweet potatoes and 鈥渟tandard鈥 potatoes is that the edible portion of the sweet potato is a tuberous root, not a true tuber (which are technically modified plant stems).
This root vegetable has deep-orange flesh and a coppery skin jacket. Sweet potatoes are commonly served cooked in mashed form or roasted whole. They may also be used as pie filling.
This tropical crop needs at least 4 months of warm weather and warm soil, but they are drought- and heat-tolerant and have few pests or diseases. Although traditionally more of a Southern crop, there are many short-season sweet potato varieties today. They will grow in the North (even parts of Canada!) when grown in sandy soil or raised beds mulched with black plastic to keep the soil warm.
Sweet Potato Slips
Note that sweet potatoes are not grown from seed. Instead, they鈥檙e grown from slips, which are sprouts from existing sweet potatoes. Slips are often available at local garden centers and nurseries, from local farmers (such as farmers鈥 markets), or mail-order companies. Or you can start your own (see below).
Before you order slips, please make sure that you have a long enough growing season to grow sweet potatoes. Most varieties will take about 90 to 120 days to mature. See your frost dates and length of growing season. Also, ensure you time your order with your planting dates in mind!
Planting
Choose a sunny spot with well-draining soil. Sweet potatoes aren鈥檛 too picky, but they do prefer soil on the sandier side. They need plenty of air space in the soil for roots to reach down. Consider growing in raised beds if your soil is clay, rocky, or compacted.
Add compost, perlite, and/or coconut coir to the growing area to build fertile, loamy soil down to 8 to 10 inches. Avoid adding animal manure, including pelleted chicken manure; it can result in spindly and/or stained roots. Also, avoid heavy nitrogen fertilizers, which produce lush leaf growth at the expense of the edible roots!
When to Plant Sweet Potatoes
- Plant slips outdoors, 3 to 4 weeks after your last spring frost or once the soil has warmed to at least 65掳F (18掳C). Nighttime temperatures should be at least 55掳F (13掳C). The trick is to plant them early enough to have time to mature fully but not so early that they get killed by a late spring frost.
- Be sure to protect young sweet potatoes from late frosts or cool nights (lower than 55掳F/13掳C), as they are very tender. Cover them with plastic milk jugs or use row covers, removing the covers during the day.
- If you ordered slips from a mail-order source, unpack them right away. Stick the roots in water for a day or so, and they鈥檒l perk up. Plant them as soon as conditions are right.
Credit: Lex20/Getty Images.
How to Grow Your Own Sweet Potato Slips
You can start your own slips instead of buying them, but it鈥檚 more work. Here鈥檚 how:
- About 8 weeks before your last spring frost date, look for unblemished, smooth, organic sweet potatoes at the store or farmers market. Be sure to ask about the variety and check that it鈥檚 one you want to grow.
- Place the whole sweet potatoes in pots or bins that contain at least 3 inches of light, organic, well-draining soil. Leave an inch or two of space between each sweet potato.
- Lightly cover with a few inches of additional soil. Water now and as needed to keep soil damp but not soggy.
- Maintain the soil and the room at 75掳F to 80掳F in sunlight or under artificial lights. Use a heating mat if necessary; sweet potatoes respond well to warm temperatures.
- Soon, slips (shoots) will emerge from the soil.
- After about 6 to 8 weeks, the slips should be between 6 and 12 inches long, with a number of leaves and roots.
- Remove the slips from the sweet potatoes with roots attached. (If no roots have formed on the slip itself, remove the slip and place it in water; roots should appear in 1 to 2 weeks.)
- If it is still too soon to plant outdoors, stand the slips in potting mix or sand and keep them moist until the right planting time (3 to 4 weeks after the last frost).
- Harden off the slips (before planting outdoors) for 1 to 2 weeks by exposing them to filtered sunlight outdoors during the day.
How to Plant Sweet Potatoes
- Create raised mounds 6 to 8 inches tall and about 12 inches wide.
- Plan 3 feet between mounds so there is enough space for vines to run.
- Plant the slips on a warm, overcast day when the soil temperature has reached 60掳F (15掳C).
- Break off the lower leaves, leaving only the top ones.
- Set the slips deep enough to cover the roots and the stem up to the leaves. Sweet potatoes will form on the nodes.
- Water with a high-phosphorus liquid fertilizer, then water generously for 7 to 10 days to make sure that the plants root well.
Growing
- Side-dress the sweet potato plants 3 to 4 weeks after transplanting with 5-10-10 fertilizer. If you have sandy soil, use more.
- Weed the sweet potato beds regularly, starting 2 weeks after planting.
- Avoid deep digging with a hoe or other tool that disturbs the delicate feeder roots.
- Water regularly, especially during mid-summer. Deep watering in hot, dry periods will help to increase yields.
- Do not prune sweet potato vines; they should be vigorous.
- Late in the season, reduce watering to avoid cracking of the sweet鈥檚 skin鈥攁 problem in storage.
Credit: Getty Images.
Growing Sweet Potatoes in Containers
Bush-type sweet potato plants are ideal for container growers. The vines that they produce are short and compact, not sprawling like typical sweets鈥攂ut the roots are full size, not miniatures.
While slips mature, prepare a large container or tub. (A too-small container can result in small, curly sweets or fewer than hoped for.) A 10-gallon container can support two or three sweet potatoes; a 20-gallon one, four to six. A half-barrel container (20 to 25 gallons) is ideal. Place the container where it will receive full sunlight every day. (It will be heavy to move once filled and planted.)
Sweets like moist but not wet soil; the medium must be well-draining and rich; sweets are also heavy feeders. Provide potting mix amended with compost, sand, bonemeal (for potassium), and wood ash (for potash). Minimize nitrogen or risk producing heavily leafy tops and spindly roots. If you purchase a bush variety, soak the roots in water for a few hours before planting.
Plant slips 3 to 4 weeks after the last spring frost, when the soil has warmed to 65掳F and nighttime temperatures are at least 55掳F. Mulch with black plastic before and during the season, if necessary, to capture or retain heat. Set slips 4 inches deep on a bed of compost, then cover up to their bottom leaves. Water with a high-phosphorus liquid fertilizer (5-10-10) for 7 to 10 days to ensure that the plants root well.
Harvesting
- You can start digging up the roots when they are big enough for a meal.
- Harvest when the leaves and ends of the vines have started turning yellow or about 100 days from planting.
- Loosen the soil around each plant (18 inches around, 4 to 6 inches deep) to avoid injuring the roots. Cut away some of the vines.
- Pull up the plant鈥檚 primary crown and dig the roots by hand. Handle the sweet potatoes carefully, as they bruise easily.
- Shake off any excess dirt; do not wash the roots.
- Complete harvesting by the first fall frost.
How to Cure and Store Sweet Potatoes
- Curing sweet potatoes gives them a sweet taste and also allows a second skin to form over scratches and bruises.
- Handle sweet potatoes carefully; they bruise easily.
- To cure, store roots in a warm place (about 80掳F) at high humidity (about 90%) for 10 to 14 days. A table outside in a shady spot works well. Arrange sweet potatoes so that they are not touching.
- After curing, discard bruised sweet potatoes, then wrap each one in newspaper.
- Carefully pack in a wooden box or basket. Store in a root cellar, basement, or the like with a high humidity at 55掳 to 60掳F.
- The roots should last in storage for about 6 months.
Cooking Notes
Relatively low in calories, sweet potatoes are very nutritious, a top source of beta-carotene, and contain some protein, calcium, iron, vitamins A and C, and other minerals. They can be stored longer than winter squash.
To cook, sweet potatoes are easier than pie (or sweet potato pie!).
- They can be scrubbed, poked with a fork in a few places, and baked at 400掳F for 35 minutes to 1 hour, until they give a bit when you squeeze them in your pot-holder鈥損rotected hand.
- In the microwave, a whole sweet potato baked on high should be ready in 4 to 6 minutes. It may still feel firm when done; let it stand for about 5 minutes to soften.
- Sweet potatoes can also be steamed whole (cleaned and unpeeled) for about 40 minutes or until tender or cooked whole (cleaned and unpeeled) in boiling salted water for about 35 minutes. (Boiling reduces the flavor considerably.)
- Immerse cut raw sweet potatoes in water until you’re ready to cook them; they will darken otherwise.
As a general rule, don’t substitute sweet potatoes for regular potatoes in recipes; the two aren’t related. Sweet potatoes don’t hold together the way potatoes do, and their strong flavor can overwhelm a dish meant for a milder potato taste. Sweet potatoes are also not related to yams. But they make a fine substitute for pumpkin, especially in desserts.
Check out our ten best sweet potato recipes!
Catherine Boeckmann
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Hi, Anna, the first question that comes to mind is, Are you rotating the crop or planting sweets in the same soil/plot year after year? Planting the same thing in the same place year after year leads to reduced harvest over time. The 鈥渁nt鈥 might be the sweet potato weevil (it looks like an ant) and digs into the tubers (filling crevices with fecal matter鈥攂ig yuck!) creating bacteria and decay. There are other sweet potato pests, too鈥攂anded cucumber beetle (yes, 鈥渃ucumber鈥), wireworms, silverleaf whitefly…but they do not look like ants.
So it you want to grow sweets next year, make a new bed and fill it with new soil (we would put it several feet or as far away from the other bed as possible), plant something else in the old bed (see this page for suggestions, based on crop rotation http://www.almanac.com/video/how-rotate-your-vegetable-crops ) and, if you can (given how late it is in season) consider growing a cover crop now in the old/sweets bed (see advice for cover crops here: http://www.almanac.com/content/cover-crops-us)
We hope this helps!
I raise beautiful sweet potatoes, and would love to have some recipts for them.reading further I see the answers ,thanks.
We grew some sweet potatoes for the first time this year. They grew really well and we had three very large single ones but the rest were in a huge tangle wrapped around each other and some very hilarious shapes. Do you know what we did wrong? They still tasted delicious by the way! Best wished , Liz Bean
Hmm. Make sure that your soil is loose and fluffy, sandy loam is good. It should not be compacted, heavy clay, or rocky. The rocks or hard soil can make the sweet potatoes grow into odd shapes. There are also some diseases that can affect the growth/shape of sweet potatoes, but it is more likely the soil. Hope this helps!
This is the 3rd year that I have grown sweet potatoes. In the past, If I plant outside of our fenced garden area, the vines have been eaten by deer, so this year I only grew them inside the fenced area. They were doing great through the end of August. The we had a lack of rain and the leaves were getting eaten to the vine (I believe it is squirrels that can get into the fenced area). By Sept 20 or so, I had a large raised bed of leafless green vines. It's now early October and I usually wait another 3-4 weeks to harvest.
Questions:
1) Any suggestions on avoiding further damage? Is it worth the energy to put netting over the bed - or some other deterrent?
2) Should I go ahead and harvest now? or wait until right before harvest
3) Any recommendations for next year. The squirrels also ate quite a few tomatoes this summer.
My years of experience of trying to keep critters from eating my garden stuff goes like this:
groundhogs - eat sweet potatoes, young cabbage family plants
deer - eat sweet potatoes, pepper plants, cantaloupes, apples
squirrels (gray squirrels not fox squirrels) - eat the seeds inside your pears, and occasionally other weird stuff like tomatoes.
Which has led us to referring to fox squirrels as "good squirrels" and gray squirrels as "tree rats".
turtles - eat cucumbers, cantaloupes
rabbits - occasionally, but rarely eat young pea plants, I really don't have problems with the local rabbits.
Raccoons - will eat your corn, in fact they will even sample it to see if it's ready, before they come around and lay waste.
best solutions for a unfenced garden - hot wire, placed at waist high for deer and 6 inches off the ground for ground critters. If the deer are suburban deer, they can be very smart - like learning to jump a hot wire. So in the past, I have resorted to 2 hot wires placed 4 feet apart so they can't jump over both.
Goodness! So sorry to hear about your sweet potato troubles. Here are some thoughts.
1) If you think it might be squirrels, you might visit the following page for tips on control: http://www.almanac.com/pest/squirrels
If you think there is a possibility that another animal, such as a rabbit, might be the culprit, here is an article that helps to identify what animal might be causing damage: http://www.almanac.com/blog/gardening-blog/be-critter-detective
http://www.almanac.com/pest/rabbits
2) You might dig up one potato to assess its condition. If it looks like it needs a little more time, then wait for the harvest a little longer. If the vines are still green, it could be that the potatoes are still getting the nutrients they need to grow/mature. If the vine is starting to yellow at the tips, or a frost is expected, then harvest them as they are.
3) Try to identify the exact culprit, whether it is entering the garden from holes underground or from climbing the fence. If from overhead, you might, as the least expensive option, try covering the plants with row covers or plastic tunnels. A determined squirrel may chew through it, but it might deter some. Chipmunks can easily get under those, however. For those the burrow, as well as climb, a more elaborate physical barrier system may be needed to enclose your garden (such as wire overhead fencing to deter climbers, and wire mesh buried in an L-shape pointed outward along the perimeter to deter diggers). Motion-detector sprayers might be another option. Repellents may also help.
Thank you for your recommendations. The vines are sprouting new leaves - so even if the potatoes are not as big- maybe I can harvest some tasty leaves ( if I can keep the critters from them!
I have covered the area with netting.
I inspected the perimeter of our deer fencing and did find a small area that was not as secure and sure enough, there was evidence of burrowing under the fence. So, I've taken steps to block that entrance and will need to secure it better before next year's growing season. I guess that also explains why my planting of seeds for a fall crop keep getting eaten down.
Thank You for your response.
Where Could I Found Selected And Improved Seedlings?
1.can sweet pot vines be be trellused or guided up over a pergola
2.is growing season long enough in upper peninsula,marquette mi. When would the slips get planted
3. What are yams
