Last Updated on September 17, 2026
How to Cure Sweet Potatoes at Home (Temperature, Humidity and Days)
To cure sweet potatoes, hold them at about 85°F and 85-90% relative humidity for 4 to 7 days, then store them at 55-60°F. If you can’t get that warm, a spot in the 70s works but takes 2 to 3 weeks. Keep them above 50-55°F at every stage, don’t wash them first, and never put them in the refrigerator.
The numbers to hit
| Stage | Temperature | Humidity | How long |
|---|---|---|---|
| Cure, ideal | 80-85°F (85°F is the usual target) | 85-90% | 4 to 7 days |
| Cure, warm room | In the 70s, as warm as you can get it | As high as you can hold without water beading on the roots | 2 to 3 weeks |
| Store | 55-60°F | 80-90% | 3 to 12 months |
| Sprouting risk | Above 60-65°F | High humidity makes it worse | During storage |
| Chilling injury | Below 50-55°F | n/a | Adds up with every cold hour |
| Ruined | About 30°F (the roots freeze) | n/a | Immediately |
These ranges come from twelve university and extension sources, compared side by side at the bottom of this page. The curing target is from NC State Extension’s postharvest guide (85°F, 85-90% humidity, 3 to 5 days in a commercial curing room), Penn State Extension (80-85°F, 85-95%, 4 to 7 days) and Alabama Extension (85°F, 90-95%, 4 to 7 days). Washington State University says curing works at lower temperatures and just takes longer, 2 to 3 weeks.
How low is too low is where the sources split. Purdue’s Indiana Yard and Garden allows 65-75°F near a furnace for 2 to 3 weeks. Clemson’s Home and Garden Information Center says no curing happens below 70°F, and NC State found that curing below 75°F increases weight loss and shortens storage life. So warmer is better, and the 70s are the practical floor.
Why curing matters
A freshly dug sweet potato is still alive and still changing. Curing does three things:
- It heals wounds. NC State explains that a cut root oozes sticky latex that dries in a few hours and looks sealed, but gives little protection against decay or weight loss. Warm, humid curing builds a real barrier under the wound, finished by a skin-like layer the guide calls suberization.
- It turns starch into sugar. Proper curing increases moistness, sweetness and aroma while starch goes down and sugars go up, according to the same guide.
- It makes them keep. Washington State University says uncured sweet potatoes last only a few weeks, while properly cured roots can store for 12 months or more.
That is close to the opposite of garlic and regular potatoes. The garlic curing guide on this site dries garlic in a shady, dry spot for 2 to 3 weeks and stores it at 45 to 50% humidity, and the potato growing guide cures regular potatoes for a week or two somewhere cool, dark and well ventilated. Sweet potatoes want heat and moisture. They are much closer to winter squash; WSU notes that some farmers cure the two crops together.
Before you dig: beat the cold soil
Sweet potatoes are a very tender crop (University of Maryland Extension’s word), and the roots are hurt by cold long before the ground freezes. Penn State Extension says to lift them before frost or before the soil drops below about 55°F. University of Maryland Extension and Purdue both put chilling injury at soil temperatures of 50°F or lower. Maryland adds that if frost kills the vines you should dig right away, because decay in the dead vines moves into the roots, and Purdue says the biggest danger from digging late is cold, wet soil rotting the roots.
Your first fall frost is the deadline, so know when it usually arrives: look up your frost dates by zip code on the Plan My Garden frost date page.
Set up your curing space the day before you dig. NC State reports that a delay of as few as 12 hours between harvest and curing hurts the result, and WSU says the same day is best.
Dig day: handle them like eggs
- Cut the vines first. Clemson says it is best to cut and remove the vines before digging, and Maryland says it makes the digging easier.
- Loosen, then lift. Use a garden fork to loosen the soil and lift the roots out. The skin is easily damaged. Penn State says to lift carefully rather than pull on the vines, and NC State says roots should never be thrown or stepped on. Purdue suggests lining your containers with rags or other soft material so the roots don’t get scratched.
- Keep them out of the sun. NC State says sunscald can start after as few as 30 minutes in bright sun, and harvested roots should never be left out overnight.
- Don’t wash them. NC State’s Plants for Human Health Institute, Penn State, WSU and Alabama Extension all say to cure them unwashed; brush off loose soil gently. Purdue goes further and says to let the roots dry and cure before removing the excess soil.
- Sort. Penn State recommends separating damaged or sun-exposed roots and using those first. Purdue says not to store badly injured or diseased roots at all.
- Weigh one crate. Write the number down. It becomes your check at the end of curing.
Home curing setups that work without a greenhouse
NC State’s Plants for Human Health Institute points out that the 85°F target is easy in a greenhouse and harder at home, and LSU AgCenter says to pick a room or building that comes close. These are the small-batch setups that universities and a garden teacher actually describe. Whatever you use, Penn State says to put a thermometer and hygrometer near the roots.
| Setup | How it works | Described by |
|---|---|---|
| Closet, cabinet or small room | Small space heater on a thermostat controller, a household humidifier or wet towels in trays, a small fan on low. Keep the heater away from anything flammable. | Penn State Extension, WSU |
| Near the furnace | Stack crates or boxes near the furnace and cover them with paper or heavy cloth to hold humidity, or pack the roots in perforated plastic bags. At 65-75°F, plan on 2 to 3 weeks. | Purdue Indiana Yard and Garden |
| Spare bathroom or laundry room | A small room that can get wet becomes the chamber, with a space heater and a humidifier or a pot of hot water. | Garden teacher Chloe Lieberman in Mountain Xpress |
| Plastic tent | A PVC pipe frame covered with clear plastic and a humidifier inside, or plastic loosely draped over the crates. Penn State adds that a pop-up grow tent with a humidifier and heat mat works for small amounts. | WSU, Penn State Extension |
| Heat mat bundle | Crates set on a seedling heat mat with a dish of water, all wrapped in blankets and plastic sheets (old shower curtains work). Expect condensation to drip. | Chloe Lieberman, Mountain Xpress |
| Milk crate with a damp towel | One layer of roots in the bottom, wooden dowels pushed through the side holes to hold a second layer, a damp towel over the top, set in a warm, dry, shady spot outside or in a garage. | NC State Plants for Human Health Institute |
| Burlap or plastic bag | A single layer in a burlap bag with a moist towel on top, or in a plastic grocery bag with several holes poked in it, tied shut, in a sunny window or a warm, shady spot outside. | NC State Plants for Human Health Institute |
| Warmest room in the house | Usually the kitchen, for 14 days. A loose plastic cover over the roots raises the humidity. | Clemson HGIC; the plastic cover from University of Missouri Extension |
| Covered porch or garage | A week or so, roots in a single layer on a mesh screen, protected from rain and animals. Maryland calls this a partial cure that works best when harvest weather is still warm and humid. | University of Maryland Extension |
If you use damp towels or paper bags, Lieberman says to remoisten them every day. If you use a heater, watch the roots closest to it: WSU warns they can overheat. Overshooting happens even in commercial rooms. NC State says temperatures there can run up to 90°F or even 100°F because the roots give off heat as they respire, and recommends setting the curing thermostat no higher than 80°F so the roots coast up to 85°F.
None of the extension guides on this page describe curing in a kitchen oven. Every setup they give holds gentle warmth and high humidity steadily for days.
Curing in a cold climate
The porch, garage and crate-outside methods borrow warmth from the weather, and Maryland says its porch method works best when harvest weather is still warm and humid. If your garage sits below 70°F, Clemson says no curing happens, and if it drops below 50°F overnight the roots are injured. Bring the roots inside: to a closet, small room or tent with a heater and humidifier, or to a spot near the furnace as Purdue describes. WSU’s guide was written for northwestern Washington, and it relies on exactly those setups, plus heat mats or a space heater to hold an unheated greenhouse warm overnight. Expect it to take longer, too: NC State says the bigger the gap between the roots’ temperature at harvest and 85°F, the longer curing takes.
Check the numbers with a cheap thermometer-hygrometer
A digital thermometer-hygrometer is the whole toolkit. Penn State says to monitor temperature and humidity at root level, morning and evening. Set it among the roots, not on the side nearest the heater.
- Check the hygrometer with salt. Humidity instrument maker Vaisala explains that a saturated table salt (sodium chloride) solution holds a sealed chamber at about 75% relative humidity, that it stabilizes slowly, and that it needs a stable temperature. To use that at home, stir salt into a little water until some stays undissolved, seal the cup and your hygrometer together in a container at steady room temperature, and wait until the reading stops changing. If it settles at 80%, your hygrometer reads about 5 points high, so keep that in mind when you read it in the curing space.
- Look for water on the roots. NC State says humidity should be as high as possible, but not to the point where water shows on the walls, floors, bins or the sweet potatoes. WSU adds that moisture collecting on the roots leads to mold and rot.
- Weigh the crate again at the end. NC State says normal weight loss should not exceed 5 to 8 percent of the fresh weight. For a 20 pound crate that is 1 to 1.6 pounds. NC State links extra loss to curing that is too cool (below 75°F) or goes on too long.
Day-by-day checklist
| When | Do | Check |
|---|---|---|
| Day before digging | Set up the space and turn on the heat and humidity | 80-85°F and 85-90% on the hygrometer |
| Day 0 (dig) | Cut vines, dig, sort, weigh a crate, start curing the same day | No roots left in the sun or out overnight |
| Days 1 to 3 | Read the gauges morning and evening; remoisten towels daily | Temperature steady, no water beading on the roots |
| Days 4 to 7 | Start checking for done | Firm roots, skin that doesn’t rub off, healed-over cuts |
| Days 8 to 21 | Only if your space runs in the 70s: keep going | Same signs of done |
| End of curing | Weigh the crate, move roots to 55-60°F storage | Weight loss no more than 5 to 8 percent |
| Every week after | Look over the stored roots | Temperature, humidity, soft spots or sprouts |
| 6 to 8 weeks after digging | Bake them | LSU AgCenter says they bake up sweet and moist by now |
What done looks like
WSU describes properly cured sweet potatoes as firm, with skin that doesn’t rub off easily, healed-over wounds, and a sweet taste. University of Minnesota Extension uses the same test: they are done when the wounded areas have healed. A few short sprout buds, under a quarter inch, on a few roots near the end is normal according to NC State. Widespread sprouting means they cured too long.
If something looks off, Penn State’s troubleshooting list covers the common problems:
| Problem | Likely cause | Fix |
|---|---|---|
| Shriveling | Humidity too low or too much airflow | Raise humidity, slow the fan |
| Surface mold | Too much humidity with still air | Add a little airflow |
| Hard center after cooking | Chilling injury | Warm up storage, use those roots soon |
| Early sprouting | Warm or light storage | Hold at 55-58°F in the dark |
Storing cured sweet potatoes
Once cured, move them to a dark, ventilated spot that holds 55-60°F. WSU and Purdue both suggest wrapping the roots in newspaper (WSU also mentions a paper bag) and keeping them in a cool closet; Maryland suggests a basement, in boxes or baskets lined with newspaper. Penn State adds four rules: keep them dark, don’t seal them in unvented bins, don’t store them near apples or onions (the ethylene speeds sprouting), and never refrigerate them.
Steady matters as much as the number. NC State expects swings of three or four degrees, but says swings of more than five degrees lead to early breakdown and extra weight loss. If you store them in a garage or on a porch, check the thermometer on the coldest mornings to be sure it still holds 55-60°F.
Cold damage is sneaky. NC State says chilling injury depends on both temperature and time: one hour at 40°F can do the same harm as five hours at 45°F, and the damage may not show for many weeks or even several months. Alabama Extension lists what it looks like: discolored flesh, internal breakdown, off-flavors, hard cores when cooked, and more decay. Too warm is a problem too; above 60°F, WSU says, they start to sprout, and hot, dry storage can make the flesh pithy in some varieties.
When they taste best
You can eat sweet potatoes the day you dig them, as N.C. Cooperative Extension in Burke County and Purdue both point out, but Purdue says curing greatly improves their flavor and storage quality. LSU AgCenter says fresh-dug roots are not very sweet or moist. They don’t bake into a great product yet, though they can be candied or used in sweetened pies and casseroles. It takes 6 to 8 weeks of curing and storage at 55-60°F before they bake up sweet and moist. Maryland agrees that the sugar content keeps slowly rising in storage.
Where the numbers come from
| Source | Cure at | Humidity | Days | Store at |
|---|---|---|---|---|
| NC State Extension (commercial) | 85°F | 85-90% | 3 to 5 | 55°F, 85-90%, up to 13 months |
| NC State Plants for Human Health Institute | 85°F | 80-90% | 4 to 14 | Cool, dry, ventilated; 6 months or more |
| N.C. Cooperative Extension, Burke County | About 85°F | 85-95% | 5 to 7 | 55-65°F |
| Alabama Extension | 85°F | 90-95% | 4 to 7 | 55-60°F, 80-85%, 4 to 7 months |
| Penn State Extension | 80-85°F | 85-95% | 4 to 7 (up to 10 if heavily skinned) | 55-60°F, 85-90%, 3 to 6 months |
| Washington State University | 80-90°F | 80-90% | 7 (14 to 21 if cooler) | 55-60°F, 80-90%, 6 to 12 months or more |
| Clemson HGIC | 85°F | 90% | 7 (14 in a warm kitchen) | Cool, never below 50°F; over 6 months |
| Purdue Indiana Yard and Garden | 80-85°F | 85-90% | About 10 (14 to 21 at 65-75°F) | About 55-60°F, dark |
| LSU AgCenter | 80-85°F | 80-90% | 5 to 10 | 55-60°F; several months or more |
| Iowa State Extension | 80-85°F | 90-95% | 7 | 55-60°F, 85-90%, 4 to 6 months |
| University of Maryland Extension | 85°F (commercial) | 80-90% | 5 to 10 | 55-60°F, 85-90% |
| University of Missouri Extension | 80-85°F | Humid, under loose plastic | About 10 | 55-60°F, 6 to 10 months |
Quick questions
How long do sweet potatoes need to cure?
4 to 7 days at about 85°F and 85-90% humidity. In a warm spot in the 70s, give them 2 to 3 weeks. Purdue allows 65-75°F near a furnace for 2 to 3 weeks, but Clemson Extension says no curing happens below 70°F, so keep them as warm as you can.
Do sweet potatoes need to cure before eating?
No, you can cook them the day you dig them. They just won’t be very sweet yet. LSU AgCenter says fresh-dug roots can be candied or used in sweetened pies and casseroles, and that it takes 6 to 8 weeks of curing and storage before they bake up sweet and moist.
Can I cure sweet potatoes in the garage?
Only while the garage stays warm. NC State’s Plants for Human Health Institute describes curing in a milk crate under a damp towel in a garage, and Maryland Extension a week in a garage for a partial cure. Clemson says no curing happens below 70°F, and below 50°F the roots are injured, so check the garage with a thermometer first.
Can you store sweet potatoes in the refrigerator?
No. Clemson, Penn State, Purdue and Missouri Extension all say to keep them out of the refrigerator. Cold causes chilling injury: Alabama Extension lists hard cores when cooked, off-flavors, discolored flesh and more decay. Store them at 55-60°F instead.
How do I cure sweet potatoes in a cold climate?
Bring them inside. Porch and garage methods depend on warm harvest weather. Use a closet, small room or plastic tent with a heater and humidifier (Penn State and Washington State University) or a spot near the furnace (Purdue), and dig before the soil drops below about 55°F.
Know your frost dates before next fall
Your first fall frost sets the digging deadline, so it helps to know it before the season starts. Plan My Garden is free to start: enter your zip code and it finds your frost dates, then draw your beds, pick your crops, and it places each plant at square-foot spacing and builds a planting schedule from your frost dates.
Related: Harvesting and Curing Garlic · Planting and Growing Potatoes · How to Ripen Green Tomatoes Indoors · Harvest and Preserve guides · Garden Charts and Calculators
