Sweet Potatoes: How to Grow Sweet Potatoes From Slips to Harvest
Plant sweet potato slips 3 to 4 weeks after your frost-free date once the soil reaches 65 F, most often 12 to 18 inches apart, ideally on a raised ridge. Guides split on harvest: some dig before frost, others around the first fall frost. Cure the roots warm and humid, then store them dark and cool, at 50 to 65 F.
Sources: University of Maryland Extension, Penn State Extension, Illinois Extension, N.C. Cooperative Extension and 7 more. See the sources we used. How we source our guides
On this page
Grow sweet potatoes from slips, sprouts grown from a stored root, and plant them 3 to 4 weeks after your frost-free date, when the soil has reached 65 F. Set slips most often 12 to 18 inches apart, ideally on a raised ridge, and dig in fall, before the soil turns cold: some guides dig ahead of the first frost, others around or just after it.
Despite the name, sweet potatoes are not potatoes: the sweetpotato is only distantly related to the potato, a nightshade, and belongs to the morning glory family.
| Sun | Full sun, at least 6 to 8 hours a day; 8 to 10 preferred |
|---|---|
| How to start | Slips, the sprouts of a stored root; not seed |
| When to plant | 3 to 4 weeks past the frost-free date |
| Soil temperature | 65 F |
| Spacing | Most often 12 to 18 inches apart (6 to 18 across guides); rows 3 to 4 feet apart |
| Planting depth | 3 to 6 inches, with two or more nodes buried |
| Days to maturity | 85 to 125 for most varieties; 4 to 5 months in one guide; usually 130 to 170 for full-size roots in another |
| Soil pH | 5.5 or 5.6 to 6.5 in two guides; 6.0 to 7.0 in a third |
| Water | Once established, about 1 inch a week in one guide, at least 1 inch in another, half an inch in a third |
| Harvest | Typically before the soil cools below 60 F; guides split on digging before, around or after the first fall frost |
| Storage | 50 to 65 F after curing, dark, never refrigerated |
Sweet potatoes grow from slips, not seed
Sweet potatoes flower little and set little or no viable seed, so each crop comes from sprouts of stored roots. Slips are the sprouts on last year's roots, and you can buy them by mail order, from nurseries or at farmers' markets.
A good slip is firm and green. One guide wants it 8 to 12 inches long, ideally with a leaf or two; another wants 4 to 5 leaves. A slip may come with roots or without them: one guide plants slips with no visible roots at all, while another wants a healthy root system. One guide says to always buy plants raised from certified disease-free roots, and another notes that saved roots can pass disease to the new crop; others grow their own slips, as below.
Sweet potato varieties: vining and bush types
Most vines run long: they can reach 20 feet, and most varieties root wherever a stem touches the ground. Bush types such as Porto Rico and Vardaman stay compact, at about 2 feet per plant, and Bush Porto Rico has short vines of 18 inches. Skip the ornamental vines: cultivars bred for showy foliage rarely make good edible roots. Lists give different days to maturity for the same variety:
| Variety | Days to maturity | Lists that name it |
|---|---|---|
| Beauregard | 90 to 110 | 3 of 3 |
| Centennial | 90 to 100 | 3 of 3 |
| Covington | 110 to 120 | 1 of 3 |
| Georgia Jet | 90 to 100 | 2 of 3 |
| Jewel | 100 to 135 | 3 of 3 |
| Bush Porto Rico | 110 | 2 of 3 |
| Vardaman (bush) | 110 | 2 of 3 |
Each range runs from the lowest to the highest figure the lists give for that variety. None of the three lists says what its days count from; one general guide counts its 90 to 120 days from the day the slips go in.
How to grow sweet potato slips at home
Sprout your own slips 6 to 8 weeks before planting time from small to medium roots about 1 1/2 inches across.
- Bed the roots in damp sand or potting soil. Half bury them whole, on their sides, or halve them the long way and lay them cut side down.
- Keep them warm and covered. A lid or plastic holds moisture in until shoots appear.
- Give the shoots light. Grow them under fluorescent or LED lights for 14 to 16 hours a day, or in a sunny spot.
- Harden them off and take them. Move the box outdoors a little longer each day for a week or two, then take the 3 to 5 slips each root gives, pulled or cut free; one guide also trims off the bottom inch.
| Step | Range across the guides |
|---|---|
| Start | 6 to 8 weeks before planting; slips are ready in about 6 weeks in three guides |
| Warmth | 70 to 85 F; two guides give it as soil temperature |
| Slips ready at | About 6 to 13 inches long, or 6 to 10 well-developed leaves |
| Taking them | Pulled in four guides; cut, not pulled, in one; separated with the bottom inch cut off in one |
A root in a jar of water is the other route. One guide suggests it for a few plants; others say sweet potatoes are prone to rot, making it riskier, and that water-rooted slips often have weaker roots for lack of air. If slips are ready before the weather is, pot them up and keep them warm, sunny and watered.
When to plant sweet potatoes: warm soil after frost
Sweet potatoes go in well after the last frost: 3 to 4 weeks past the frost-free date, once the soil reaches 65 F, because the plants are very sensitive to soil that is still cool. The crop is very tender: frost injures the tops.
Set them out as soon as the soil has warmed after the last frost, for the longest warm season. Two things can speed early growth: a ridge dries out and warms sooner than flat ground, and black plastic mulch traps solar heat in the soil.
The table counts 3 to 4 weeks on from each station's median last spring 32 F night (1991-2020 climate normals). Those dates are our arithmetic, not a date any source gives; the next column is the planting window a guide for that area gives. At all four stations the local windows sit at the late end of the arithmetic or after it, so go by the 65 F soil reading.
| Station (1991-2020 normals) | Median last spring 32 F | 3 to 4 weeks later (our arithmetic) | Local planting window | Median first fall 32 F |
|---|---|---|---|---|
| Des Moines, IA | Apr 18 | May 9 to May 16 | Mid-May to early June | Oct 20 |
| Harrisburg, PA | Apr 9 | Apr 30 to May 7 | End of May or beginning of June in most of Pennsylvania | Nov 2 |
| Raleigh-Durham, NC | Mar 31 | Apr 21 to Apr 28 | Piedmont: May 1 to mid-July | Nov 4 |
| Jackson, MS | Mar 14 | Apr 4 to Apr 11 | Early May through June | Nov 14 |
A median frost date is a coin flip: one year in two, a 32 F night falls after the spring date, and one year in two, before the fall one. A June 1 planting at Des Moines has 141 days to the median first fall 32 F (our arithmetic): more than the 90 to 120 days most guides give, inside the usual 130 to 170 that one guide gives for full-size roots, and in half of all falls frost comes sooner.
How to plant slips: spacing and ridges
Plant slips on ridges: a ridge warms faster in spring, drains better, gives the roots room and makes digging easier. Ridge size, spacing and depth vary from guide to guide:
| Range across the guides | |
|---|---|
| Ridge height | About 8 to 12 in; 12 to 15 in on heavy soil and usually 8 to 10 on sandy soil in one guide |
| Ridge width | 12 in to about 18 in |
| In the row | 6 to 18 in; most guides give 12 in or 12 to 18 in |
| Between rows | 3 to 4 ft; usually 30 in on sandy soil in one guide |
| Slip depth | 3 to 6 in, with two or more nodes buried |
Bury some nodes, the points on the stem where leaves and roots start: at 6 inches deep, at least two nodes go underground with at least two leaves above. Plant in the evening to reduce stress and wilting, ideally on a cloudy day, and water each slip in right away.
Give them loose, well-drained soil: too much nitrogen gives many leaves but few roots, and heavy clay or rocky soil makes misshapen roots. One guide loosens the soil with 1 to 2 inches of compost worked in; another, using compost as the fertilizer, applies no more than 1 inch per 100 square feet.
Growing sweet potatoes in containers
Choose a bush variety for pots: Porto Rico and Vardaman can succeed in large containers, and bush types can work in containers with extra attention to water and fertilizer. One guide usually suggests one plant per 10-gallon container, fabric grow bags included; another counts sweet potatoes among the more challenging container crops.
Watering and vines through summer
Keep new slips' soil evenly moist for their first two weeks; one guide waters them daily, while another waters young plants 1 to 2 times a week if rain is lacking. The crop is sensitive to drought for its first 50 to 60 days. After that the weekly amounts differ: about 1 inch from rain or the hose in one guide, at least 1 inch in another, half an inch in a third.
Ease off at the end: stop or limit watering 3 to 4 weeks ahead of harvest to protect the roots, since heavy rain or too much irrigation then may split them.
Weed by hand or hoe until the vines take over and shade out most weeds, and avoid deep cultivation, which can damage the roots.
Guides split on trimming vines. One says they can be cut back 20 to 30 percent; two others say not to cut or prune them during the season, since damage before the roots mature can make the roots sprout in the soil. Squash and sweet potato stems can also be tied to a trellis.
Voles, deer, scurf and other problems
Sweet potatoes run into fewer pest and disease problems than most garden crops. The ones that do turn up:
- Voles and mice. Mice may burrow into the ridge and eat the roots. Check the swelling roots for vole feeding; raised beds or large containers keep rodents out.
- Deer and groundhogs. Fence them out. Repellents and fences can deter deer without always stopping them.
- Scurf. Dark spots or black splotches confined to the skin. The roots are still fine to eat, though they may not keep as well, and scurf can spread in storage. Look for resistant varieties and rotate; soil at pH 5.8 to 6 can also control it.
- Insects. In Indiana there are few: chiefly flea beetles on young plants, plus possibly damaging sweet potato leaf and tortoise beetles about 1/4 inch long. Sweetpotato weevils can be a problem in south Mississippi.
Rotation keeps soil diseases down. Guides give gaps of two to four years: no sweet potatoes where they grew in the last two years, a 3- or 4-year cycle, or 4 years against scurf.
What to plant with sweet potatoes
In our reading, few extension pages name sweet potato companions. Okra can be interplanted with sweet potatoes as a groundcover, and where space is limited, set the low vines south or west of taller crops so they keep their sun. For crops with better-documented partners, see the companion planting chart.
When to harvest sweet potatoes
Dig sweet potatoes once the roots reach a size you want and before cold soil harms them. Most varieties take 85 to 125 days; one guide gives 4 to 5 months, and another usually 130 to 170 days for full-size roots, with smaller ones up to a month sooner. The roots never truly ripen, and the only way to tell is to dig some up and look. Start checking size at 80 to 85 days, since overgrown roots can split.
Frost is where the guides part ways:
- Before frost. Three guides dig ahead of frost: as soon as the roots are big enough to eat, or as the leaves begin to yellow, before the first killing frost.
- Around the first frost. Four dig around the time of the first fall frost: just before or after a frost kills the vines, or by the time it does or shortly after. Most gardeners wait for the leaves to yellow or for a first frost to damage them, but dig before the soil freezes.
- After a frost. One waits until after the first frost, saying it concentrates the sugars, then digs at once.
Soil temperature matters too. The crop is typically dug before the soil drops below 60 F, and soil at 50 F or lower can cause chilling injury or root rot. Once frost hits the vines, dig right away or cut the vines off, since decay spreads from dead vines into the roots.
Dig gently: the roots bruise easily and sit within 8 to 10 inches of the surface. Digging dry soil skins more roots, and over an hour of direct sun can sunburn them. Do not wash them before storage.
How to cure and store sweet potatoes
Cure sweet potatoes before you store them. A spell somewhere warm and humid heals small cuts and turns some of the starch into sugar. The figures vary from guide to guide:
| Range across the guides | |
|---|---|
| Curing temperature | 80 to 85 F, often about 85 F; or 65 to 75 F if that is what you have |
| Curing humidity | 80 to 95% RH |
| Curing time | 5 to 14 days at 80 to 85 F; 2 to 3 weeks at 65 to 75 F |
| Home curing | Slit plastic bags in a sunny room; near the furnace; a container covered with plastic in a warm room, which might do it in 5 to 7 days; air-dried 10 to 14 days somewhere warm and shady; a week or so on a porch or in a garage for a partial cure |
| Storage temperature | 50 to 65 F, dark; the most common range is 55 to 60 F |
| Storage humidity | 85 to 90% RH where a figure is given; others say a cool, dry spot such as a basement |
| How long | 3 to 6 months, or until spring |
RH is relative humidity.
At home, seal the roots in plastic bags with a few slits cut in them and set them in a sunny room, or cure them near the furnace when better facilities are lacking. One guide finds roots usually store fine even without the one-week cure, and its partial cure on a porch is most effective after an early fall harvest, while the air is still warm and humid.
Store cured roots somewhere dark and cool, never in the refrigerator. Guides split on how cool: two warn that below 55 F for extended periods roots can turn hard-cored or off-flavored, and that above 60 F they may sprout, while others store them at 50 to 55 F or 50 to 60 F.
Sweet potato slips and supplies
Order slips early. They are often hard to find, though online sellers carry them, and ordering early gets you the varieties you want. Beyond slips, you may want a 10-gallon container or grow bag for a patio plant, black plastic mulch to warm the soil, a spading fork for digging, and a mesh screen or slatted crates for curing and storage.
What you'll need for sweet potatoes
As an Amazon Associate we earn from qualifying purchases.
VIVOSUN 10 Gallon Grow Bags, 5-Pack
One guide usually suggests one plant per 10-gallon container, fabric grow bags included; another counts sweet potatoes among the more challenging container crops.
Check price on Amazon
Turboforce Black Plastic Sheeting, 4 ft x 50 ft, 4 mil
Black plastic mulch to warm the soil.
Check price on Amazon
Truper 4-Tine Spading Fork, 30-Inch, Wood D-Handle
A spading fork for digging.
Check price on Amazon
Sources we used
Every sweet potato number here is backed by one of these pages, saved when we read it in October 2026. Where they give different figures, the page shows the range or the split.
- "University of Maryland Extension: Growing Sweet Potatoes in a Home Garden"
- "University of Maryland Extension, Maryland Grows: Try Growing Sweet Potatoes This Year!"
- "University of Maryland Extension: Growing Vegetables in Containers and Salad Tables"
- "University of Maryland Extension: Vegetable Succession and Companion Planting"
- "Penn State Extension: Sweet Potatoes, a Winning Vine for Your Garden"
- "Illinois Extension, Home Vegetable Gardening: Sweet Potato"
- "Illinois Extension, Good Growing: How sweet it is growing sweet potatoes"
- "N.C. Cooperative Extension, Burke County Center: Harvesting and Curing Sweet Potatoes"
- "N.C. Cooperative Extension, Pamlico County Center: The Sweet Season Is Here: Sweetpotatoes"
- "NC State Extension Gardener Plant Toolbox: Ipomoea batatas"
- "NC State Extension Gardener Handbook: 16. Vegetable Gardening"
- "Iowa State University Extension: Growing Sweet Potatoes in Iowa"
- "Iowa State University Extension: How do I harvest and store sweet potatoes?"
- "Mississippi State University Extension: Growing Sweet Potatoes at Home"
- "Purdue Extension: HO-136, The Sweet Potato"
- "Utah State University Extension: How to Grow Sweet Potatoes in Your Garden"
- "NOAA NCEI: U.S. Climate Normals, 1991-2020": median 32 F freeze dates, spring and fall, for the Des Moines, Harrisburg, Raleigh-Durham and Jackson airports
Related guides
- Okra, which can be interplanted with sweet potatoes.
- Squash and pumpkins, long vines that can also be tied to a trellis.
- Melons, a warm-season crop usually planted after the last frost.
- Peppers, another warm-season crop.
- Tomatoes, also warm-season.
- Cucumbers, a warm-season vine.
- Companion planting chart.
Frequently asked questions
When should you plant sweet potato slips?
Plant slips after frost, once the soil reaches 65 F, about 3 to 4 weeks past your frost-free date. Local dates run later: mid-May to early June in Iowa, and the end of May or early June in most of Pennsylvania.
How do you know when sweet potatoes are ready to harvest?
Dig a test hill and check the roots' size: sweet potatoes never truly ripen, and digging is the only way to know. Timing varies: 90 to 120 days after planting in several guides, 4 to 5 months in another, or usually 130 to 170 days for full-size roots in a third.
Can you grow sweet potatoes in containers?
Yes, bush varieties such as Porto Rico and Vardaman can grow in large pots, since they spread only about 2 feet per plant. One guide usually suggests one plant per 10-gallon container, though another lists sweet potatoes among the harder crops to grow in pots.
How do you grow sweet potato slips at home?
Bed a stored sweet potato in damp sand or potting soil 6 to 8 weeks before planting time and keep it warm, 70 to 85 F. Each root sends up 3 to 5 slips, ready at about 6 to 13 inches long; harden them off, then pull them or cut them free.
How far apart do you plant sweet potatoes?
Most guides set sweet potato slips 12 inches or 12 to 18 inches apart in the row; across all of them the range is 6 to 18 inches. Plant them ideally on a raised ridge about 8 to 12 inches tall, set 3 to 6 inches deep, and leave 3 to 4 feet between rows for the vines.
Are sweet potatoes related to potatoes?
Only distantly: the potato is in the nightshade family, while the sweet potato belongs to the morning glory family, with morning glories and bindweed. Sweet potatoes are storage roots rather than tubers, and moist-fleshed ones often sold as yams are not true yams either.
How do you cure sweet potatoes?
Cure dug roots warm and humid: 80 to 85 F with 80 to 95 percent humidity for 5 to 14 days, by the guides' figures, or 2 to 3 weeks at 65 to 75 F. Then store them dark and cool; two guides warn against storing below 55 F, while others store as low as 50 F.
Can you plant a sweet potato from the grocery store?
You can, though guides differ on whether you should. Two start slips from store-bought roots, and a third washes them first to rinse off sprout-blocking chemicals. Another calls the practice questionable, since the variety is probably unknown and may not be adapted to conditions where you grow, and one advises plants from certified disease-free roots.