Stephen Albert
Sweet potatoes are tender, warm-season perennial plants grown as annuals.
Table of Contents
Sweet Potato Quick Growing Tips
- Sweet potatoes require a long, warm growing season, usually about 4 months of frost-free weather to reach harvest.
- Set sweet potato starts or slips in the garden after all danger of frost has passed, usually 4 weeks after the last average frost date in early summer.
- Sweet potatoes grow best where the air temperature remains very warm, from 75° to 95°F (24-35°C) throughout the growing season.
- Sweet potatoes are best started indoors as early as 12 weeks before they are placed in the garden.
- Sweet potatoes require from 100 to 150 days to reach harvest.
Where to Plant Sweet Potatoes
- Plant sweet potatoes in full sun.
- Grow sweet potatoes in loose, well-worked, well-drained loamy or somewhat sandy soil with aged compost added.
- Prepare the planting bed by adding aged compost and aged manure or a commercial organic planting mix across the bed then turn the soil 12 inches (30cm) deep.
- Soil that is overly rich in nitrogen will produce more foliage than tubers.
- Remove all soil lumps, rocks, or other obstacles from the planting bed; if tubers hit an obstacle as they develop, they will grow deformed.
- Sweet potatoes prefer a soil pH of 5.0 to 6.5.
Sweet Potato Planting Time
- Set sweet potato starts in the garden after all danger of frost is past in spring, usually about 4 weeks after the last frost.
- Sweet potatoes are extremely sensitive to frost and need a warm, moist growing season of as many as 150 days.
- Sweet potato slips can be started indoors as early as 12 weeks before they are transplanted into the garden.
- Well-rooted sweet potatoes require a soil growing temperature of 60° to 85°F (16-29°C) and an air growing temperature of 65° to 95°F (18-35°C).
- Sweet potatoes will thrive in air temperatures as high as 100°F (37°C).
Starting Sweet Potato Sprouts or Slips Indoors
Grow sweet potatoes from rooted sprouts, called slips, taken from a mature tuber. Here are two ways to start sweet potato slips:
- Place the sweet potato in a jar of water that is half full with about one-third of the tuber submerged. Leave it in a warm (75°F/24°C)), sunny location where it will sprout. When sprouts are 6 inches (15cm) long, pull them off the tuber and set them in water or damp sand; they will root in a few days. Start this process about 12 weeks before you plan to set the slips in the garden.
- Place cut pieces of a tuber moist sand or light growing medium with a constant temperature of about 80°F (26°C). (Use a heating mat with a thermostat to keep the soil consistently warm.) Each piece must have one or more “eyes or sprouts. Set each piece 2 to 4 inches (5-10cm) deep in sand or light soil. Shoots will appear in about 3 weeks. When shoots appear, add another inch of sand or light soil. Do not let the growing medium dry out. When sprouts reach 3 to 4 inches (7-10cm) tall reduce the soil temperature to 70°F (21°C) and grow on for another 3 weeks. Seed tubers will be rooted in about 6 weeks and can then be planted in the garden.
You can start slips in one-gallon containers or in a hotbed. If you plant in a hotbed space slips 3 to 4 inches (7-10cm) apart.
One sweet potato tuber can yield as many as a dozen slips.
Planting Sweet Potatoes in the Garden
- Set rooted slips in the garden on mounded rows 12 inches (30cm) wide and 8 inches (20cm) high; space rows 3 feet apart (.9m); plant slips at 12 to 18-inch (30-45cm) intervals.
- Plant slips so that the sprouts grow up toward the sky, not sideways. Be sure to cover all of the roots and about a ½ inch (12mm)of the stem.
- Protect tender sweet potato foliage from the direct hot sun for five days after planting. Set a floating row cover over the plants.
- Grow 5 sweet potato plants for each household member.
Companion Plants for Sweet Potatoes
- Grow sweet potatoes with other root crops: beets, parsnips, and salsify.
Container Growing Sweet Potatoes
- Grow a single sweet potato plant in a box or tub that is at least 12 inches (30cm) deep and 15 inches (38cm) wide.
- Use a light, porous soil mix.
- Place a stake or trellis in the center to support the vine which grows up and outwards.
Watering Sweet Potatoes
- Sweet potatoes will tolerate dry soil once established but will produce best if kept evenly moist, an inch of water every week (1 inch equals 16 gallons/60.5 liters) until 3 to 4 weeks before harvest.
- Do not overwater sweet potatoes; tubers will rot in soil that is too wet.
Feeding Sweet Potatoes
- Add aged compost or commercial organic planting mix to planting beds before planting. Aged compost contains all the nutrients sweet potatoes need to get started.
- Feed newly planted slips with a B-1 starter solution or compost tea.
- Add a low nitrogen fertilizer (5-10-10) to the soil two weeks before planting.
Maintaining Sweet Potatoes
- Sweet potatoes are easily trained onto trellises, lattices, or wires strung between sturdy poles.
- Keep weeds away from young plants. Mulch around plants with loose straw or chopped, dried leaves to control weeds and slow soil moisture evaporation.
- Pull weeds by hand or cultivate shallowly to avoid disturbing roots. Eventually, the foliage of the maturing sweet potato plant will shade out new weeds.
Sweet Potato Pests
- Insects are not likely to attack sweet potatoes in northern regions. In southern regions, sweet potato weevils and wireworms are common pests.
- Weevil larvae chew holes in tubers and adults chew holes in leaves. Control adult weevils by knocking them from plants and crushing them or spray with pyrethrins.
- Plant resistant varieties.
- Where heavy infestations occur remove all plants and do not re-plant in that area for three years.
Sweet Potato Diseases
- Sweet potatoes are susceptible to root rot and fungal diseases including a fungus disease called scurf.
- Plant disease-resistant varieties and keep the garden clean of debris and weeds where pests and diseases can harbor.
- Remove and destroy infected plants immediately before the disease can spread to healthy plants.
- Scurf is a fungal disease that grows on the skin of sweet potatoes. The skin develops shallow purple or grayish-brown lesions. Prevention is the best control. Plant certified disease-free slips. Rotate sweet potatoes out of an infected bed for three years.
Harvesting Sweet Potatoes
- Sweet potatoes require from 100 to 150 days to reach harvest.
- Lift sweet potato tubers when they have reached full size, commonly when leaves and vines have begun to yellow and wither.
- Carefully dig plants using a garden fork starting about 15 to 18 inches (38-45cm) from the center of the vine and working inwards lifting. Tubers will be 6 inches (15cm) or so deep in the soil. Be careful not to cut or bruise the tubers which are thin-skinned.
- Complete the harvest before the first frost in fall; tubers are damaged by freezing or cold weather.
Storing and Preserving Sweet Potatoes
- Cure (dry and harden) sweet potato tubers for 10 to 15 days after harvest. Set them in a warm spot (about 80°F) out of direct sunlight. Curing will help heal nicks and cuts and harden the skin. Curing will also improve the sweetness of the tuber.
- Sweet potatoes will store at 55° to 60°F (13-16°C) in a dry, cool, well-ventilated place for 4 to 6 months.
- Store sweet potatoes unwashed. Wrap the tubers in a newspaper when you store them; don’t let the tubers touch or they may rot.
- Do not refrigerate or store sweet potatoes at temperatures below 50°F (10°C).
- Sweet potatoes can be frozen, canned, or dried.
Sweet Potato Varieties to Grow
- Sweet potato tubers are described as “dry” and “moist” noting the texture of the tuber when eaten. “Moist” sweet potatoes are often called yams; however, the true yam is actually a different species found in tropical regions.
- Varieties: ‘Beauregard’ (moist-fleshed, 100 days); ‘Boniato’ (dry-fleshed, 120 days); ‘Centennial’ (moist-fleshed, 110 days); ‘Georgia Jet’ (moist-fleshed, 100 days); ‘Goldrush’ (140 days); ‘Jasper’ (150 days); ‘Jewel’ (moist-fleshed, 100 days); ‘Nancy Hall’ (moist-fleshed, 110 days); ‘Porto Rico’ (moist-fleshed, 110 days); ‘Southern Delite’ (moist-fleshed, 100 days); ‘Vardaman’ (moist-fleshed, 110 days); ‘White Yam’ (dry-fleshed, 120 days); ‘Yellow Jersey’ (dry-fleshed, 120 days).
About Sweet Potatoes
- The sweet potato is a tender vining or semi-erect perennial plant grown for its swollen fleshy tuber, similar to an elongated potato.
- Tubers grow underground from the vine’s central shoot.
- Tubers vary from creamy-yellow to light brown to deep red-orange in color and from 4 or 5 inches (10-12cm) to 8 inches (20cm) or more in length.
- The flesh of the tuber is yellow or gold.
- The flower of the sweet potato is pink to purple colored.
- Botanical name: Ipomoea batatas
- Origin: Tropical America and the Caribbean
More tips: How to Harvest and Store Sweet Potatoes
It’s only been about 80 days since my sweet potatoes were planted and they ate staying to have a few leaves turn yellow. It can’t be because of cool weather because we are still having highs in the 80s and 90s. Last year I harvested in November. ANY idea what else could cause this?
Low nighttime temperatures–50sF-60sF–can cause sweet potato leaves to start to yellow. Too much water or too much nitrogen can also cause leaves to yellow.
I have found that I love sweet potato leaves, and would like to grow a couple plants mostly for the greens. One of the beds in my yard only gets maybe 4 hours of sun a day, even in the summer. I made the mistake of showering tomatoes there once, and got nothing but leaves. Would the sweet potatoes grow over there if I just want the leaves from them? Summer is hot over here lows in the 60s or 70s, doo I don’t think temperature would be a problem.
Yes, you will likely get leaves but not enough sun for tubers to develop.
Hi, I tried planting sweet potatoes last year for the first time. The slips were planted a bit late in the season, but I thought that being in Spain, the weather would still be hot enough to produce potatoes. I planted 7 slips in each of the 4 50 litre containers. They were planted on 12th Aug 2018 and I emptied one container on 20th Dec and found that the roots had swelled to the size of my baby finger, so I’ve left the other 3 containers. The leaves have all died. Why did they not grow and can I leave these 3 containers to continue growing into the next warm season? The plant also never produced any flowers.
You planted late in the growing season as the days were growing shorter and cooler. Start new slips indoors this spring and plant them out into the garden or into containers 2 to 3 weeks after the last spring frost. Start your slips indoors 10 weeks before the last spring frost and set the rooted transplants outdoors 2 to 3 weeks after the last frost. Make sure the garden soil is amended with planting mix or aged compost and if growing in containers plant in a container 10 to 15 gallon container using a good potting mix. Grow sweet potatoes in full sun–at least 8 hours of direct sun each day.
Youplanted toolate. I plant mine in June and dont harvest til end ofSept.
I am wanting to grow sweet potato vines. I have purchased a bag of steamed sweet potatoes. Will steamed sweet potatoes still produce a vine?
Sweet potatoes are started from slips. Slips are shoots that grow from a mature sweet potato. You can grow slips from a sweet potato you bought at the store or one from your garden. Start slips from healthy, clean sweet potatoes. Each sweet potato can produce up to 50 slip sprouts.
What causes the vine to produce one gigantic tuber?
A potato plant that grows just one tuber is an anomaly; the cause is likely environmental or insufficient pollination. Let’s see if some potato-growing readers will weigh in on this.
My harvests always include 10% giant tubers, up to 24 inches long and 4-6 inches wide. Some round up to 8 inches in diameter. It is true that the giant round ones sometimes have fewer littermates. Size and shape have no effect on flavor. They are all just as excellent as the regular sized tubers. We peel, cube (~1″), and steam until tender. Easiest crop to grow in 50 years of gardening. I always grow them in 4-6″ gaps between 10 foot (or better 20′) wide rolls of 6 mil black plastic. Water for a week or 2, then no more water. I stab the puddles a few times w my pocket knife. Central NJ, clay soils. I give the sets a shovel full of compost mixed in. . No sprays, no fertilizer, no weeds, no lifting.BTW I am puzzled that I never see NC State Ext mention of lifting the vines, which local old timers advise. Rooting at leaf nodules will waste energy and grow little (sometimes big) tubers all over the patch. normally, my 20 foot row spacing 1.5 ft set spacing fills the plastic sheets with vines. Harvest at Halloween. OK, not so easy…getting all the tubers out w/o breaking or skinning is long and backbreaking.
I live in Denver, Colorado, an it’s the middle of winter (February) here.
I have been growing a sweet potato in the window sill, in a jar filled with water. It has four long slips, and quite a set of string like roots.
If I try to pull the slips out, and they break, will I have ruined it?
Would it be best to carve the sweet potato up four ways, so that each slip has some sweet potato, and some roots?
Should I plant the sweet potato in a big dirt pot, and keep it under an artificial light? I think it’s getting cold by the window.
Use a sharp serrated knife to cut the tuber into equal portions. Each of the four shoots should have an equal portion of the tuber (the shoots are drawing nutrients from the tuber). As well, it would be good if each new portion also had at least two growth-producing “eyes,” which are shallow depressions in the tuber’s flesh (these will allow for additional new growth). Place the newly cut portions of the tuber in a sterile (commercial) potting soil and firm in the tuber; try not to bury the slips in the soil they could rot if the soil becomes too damp. Place the new plantings under bright fluorescent lights or grow lights and keep the light about 6 inches above the growth. Place the slips in a spot that stays at least 60F, warmer is better.
Thank you.
Is it possible to grow sweet potatoes in straw like regular potatoes? A layer of wet hay, then the slips, then a 2-3 ft stack of loose straw.
I harvested slips from my grocery bought seeet potatoes. They rooted within 2 days. I placed them in May in a 10 gal pot with a patio tomato on the front porch that gets full sun all day. The vines got huge & lush. ( gets hot here in S. TX). Probably could have waited but when a few leaves turned yellow & the tomato plants were ‘done’, we just turned over the pots into a wheel barrow. To my surprise we harvested over 15 lbs of potatoes from 4 pits! ( I put 3,slips in each pot). Note: make sure to use a good quality POTTING SOIL. In one pot used just bagged ‘garden soil’ and thecyeild was drastically reduced.
Great success story!! Thanks and Happy Gardening!
South Central Kentucky here. Planted a whole sweet potato after my wife had started it indoors right after the 4th of July. Pulled them up yesterday (10/9/2020) Most were huge, one being bigger than my size 12 foot. Will they still be okay to eat that size or will they be tough as nails? Lots of fun to grow despite that they take over the ground space. Finally read the above info so I can do it right next year.
This link on sweet potato preparation may be helpful
Small- and medium-sized tubers usually make a meal. Your large tubers may be a bit tough; try cubing them and then steaming or baking.
I plant garnets and get huge tubers. The largest have always been identical to the smallest. We peel cube and steam them, until tender, with 3/4 in of water in a full 3 qt pot. Hard to get the big ones in the oven and suspect they might be raw in the middle.
Thanks for sharing this. Very interesting and helpful! Happy Gardening!!
How long can you grow tubers before planting? Planted first round way to late. Kitchen window sill full of tubers. Can they keep going through the winter until spring planting?
If the tubers have sent up stems/runners and have green leaves, you will want to plant them. The tuber is supplying the food and energy for the new growth, but the tuber can not do that indefinitely. If you live in a cold winter region, transfer the new plants to pots and grow them on in soil until they can be set in the garden. Some may fail, and you may have to start new tubers in spring.
I learnt a lot from you guys. Thanks, I’m new at potato growing.
Great resource for growing sweet potatoes! Thank you for sharing.
This is sooooo good! I am excited to try something new this season. We are in April, is it too late to start or should I opt for garden centre grown staters?
If your growing season goes into early September; get started now for planting out in the garden in mid- to late May when the soil is warm.
So I planted sweet potatoes from a whole tuber. I’m a first time planter and I thought I could plant it the way yams are planted. It has been in the ground for Almost three months. My question is would it grow well since I planted a whole tuber instead of just slips.
A whole tuber should sprout, however, it also may incur some rot since there is more flesh in a whole tuber that needed for rooting. You can plant again, cut a whole tuber into pieces each with two or three eyes. You can start the shoot growth by setting the tuber partially in water and then transplant it to the garden.
I planted my sweet potatoes in the month of June 2021, can it produce well
Sweet potatoes need 100 to 150 days to reach mature size and harvest; if you are in a warm region where frost does not arrive until the end of October, your sweet potatoes should produce well.