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How to cure sweet potatoes

By P. Allen Smith

What are the next steps after digging sweet potatoes? How do I cure the spuds I have just dug? Due to a wetter-than-usual summer, the tubers are unusually large. I would like to ensure that I don’t lose them to decay.

I’ve just finished harvesting sweet potatoes in my own garden. Like you, this year’s harvest has yielded some of the biggest sweet potatoes ever.

Sweet potato varieties are ready to harvest 95 to 120 days after planting in the garden. When the leaves turn slightly yellow they are usually ready to harvest. Because they have thin skins sweet potatoes are easily damaged during harvest so extra care should be taken. Some people even go so far as to wear cotton gloves when harvesting as to not harm the potatoes. Cutting the vines 2 or 3 days before you plan to dig will toughen up the skins.

After harvest, the sweet potatoes should be cured. This involves placing the potatoes in a warm (85 degrees) humid (90 percent) environment for about 4 to 6 days to increase sugar content, heal nicks and bruises incurred during harvest, and increase flesh color.

Once cured, store your sweet potatoes in dry boxes or bins in a room that’s humid and 55 to 60 degrees F. The ideal place to store sweet potatoes is in a root cellar or cool pantry. Do not store them in the refrigerator because low temperatures will cause the sugars to turn to starch.
They can be stored for 6 to 10 months under good conditions.

Allow roots to dry and cure before removing excess soil. Cure sweet potatoes by holding them for about 10 days at 80-85°F and high relative humidity (85-90 percent). In the absence of better facilities, they can be cured between 65-75°F for 2-3 weeks.

What is the fastest way to cure sweet potatoes?

Allow roots to dry and cure before removing excess soil. Cure sweet potatoes by holding them for about 10 days at 80-85°F and high relative humidity (85-90 percent). In the absence of better facilities, they can be cured between 65-75°F for 2-3 weeks.

How do you cure sweet potatoes at home?

Curing sweet potatoes requires a warm, humid environment for a period of four days to two weeks. Ideally, 80 to 85 degrees Fahrenheit with 80 to 90 percent humidity. The closer you come to these ideal conditions, the less time it takes to do the job.

How many sweet potatoes do you get from one plant?

Sweet potatoes are grown from rootable cuttings, often called slips. If you’ve never grown sweet potatoes before, it can be great fun to grow your own slips from small or medium-size sweet potatoes purchased at the market. One sweet potato will produce between three and five slips.

How long can sweet potatoes stay in the fridge?

Cooked sweet potatoes can last in the fridge for 3 to 5 days. To make them last longer — store sweet potatoes in an airtight plastic bag or container.

Can I cure sweet potatoes in the sun?

Move the potatoes out of the sun into a warm, dry location and lay them out in a single layer, so the skins can dry for a week or so. If you plan to use up your Sweetpotato harvest within a month or two, it isn’t necessary to “cure” them. Simply air-dry the tubers for 7 to 10 days at 75 to 80 degrees F.

Can you eat uncured sweet potatoes?

They are good boiled, mashed, candied, fried and in many cooked dishes, but uncured potatoes do not bake successfully. They must be cured several weeks before they are ready for baking, stored in a cool, dry place where the temperature is about 55 or 60 degrees.

Should I wash sweet potatoes before curing?

Some recommend washing and rinsing potatoes prior to storage. This could easily lead to rot, with too much moisture left on the sweet potatoes. If the dirt on the sweet potatoes is an issue with storing, use a dry cloth to remove any excess dirt after harvesting.

How long does it take for sweet potatoes to harvest?

Typically, most varieties will take about three to four months to mature – about 90 to 120 days, but there are some newer varieties that take less time and bred specifically for northern climates (such as Georgia Jet, Vardaman, Centennial). Some growers have mixes specifically for northern gardens.

Can you leave sweet potatoes in the ground over winter?

Sweet potatoes will continue to grow, as long as soil temperatures on average remain above 65 degrees (F), or tops are killed by frost. If you can’t get the roots dug right after a frost, cut the killed tops off just above the soil line, and you can then leave the roots in the ground for a few days.

How do you cure sweet potatoes without a greenhouse?

To maintain the required high humidity (85-90 percent relative humidity), stack storage crates or boxes and cover them with paper or heavy cloth. Once the sweet potatoes are cured, move them to a dark location where a temperature of about 55-60°F can be maintained, like an unheated basement, or root cellar.

How do you harden 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.

Are sweet potatoes perishable?

Sweet potatoes are a highly perishable crop and difficult to store for extended periods of time. This is mainly due to their high moisture content, metabolic activity following harvesting and thin, permeable skin.

What month are sweet potatoes in season?

Sweet Potatoes Seasonality In the United States, sweet potatoes are generally harvested in September and early October.

Why do sweet potatoes have to cure?

After harvest, the sweet potatoes should be cured. This involves placing the potatoes in a warm (85 degrees) humid (90 percent) environment for about 4 to 6 days to increase sugar content, heal nicks and bruises incurred during harvest, and increase flesh color.

Can you eat sweet potatoes straight from the garden?

Sweet potatoes are delicious eaten right after harvest, but their true flavors deepen as they cure. During the curing process, the starches in the tuber turn into sugar, intensifying the buttery sweet flavor and texture of the potato. Try to minimize any damage to the tuber, as it invites mold, insects, and disease.

What to do after harvesting sweet potatoes?

Sweet potatoes must be cured after harvest and before they are stored. After digging, allow the roots to dry for two to three hours. Don’t leave them out overnight where cooler temperatures and moisture can damage them. Once the surface is dry, move them to a warm, dry, and well ventilated place for 10 to 14 days.

How do you cure sweet potatoes in a plastic bag?

In order to cure for long-term storage, sweet potatoes need high humidity and heat above 80 or 85 degrees for one to two weeks. To achieve these conditions, place sweet potatoes in a single layer in a plastic grocery bag. Tie the bag closed but also cut holes in the bag for ventilation.

Do sweet potatoes get sweeter as they age?

Sweet potatoes, like fine cabernets, get better with age. Fresh out of the ground, they are considered “green” and have a high degree of starch. But if handled properly, their starch converts to sugar and, when cooked, sweet potatoes live up to their sugary appellation.

How to cure sweet potatoes

You’ve worked hard to grow healthy sweet potatoes. Keep them that way off the vine using these best practices.

One of the most important things to keep in mind when harvesting sweet potatoes is that the roots of the sweet potato are alive. The roots require sufficient oxygen to survive, even in storage. Changes in the environment, such as temperature and relative humidity, will affect the shelf life of the sweet potato. Keeping these facts in mind will help you make good management decisions for your sweet potato crop.

Sweet potatoes are usually stored in nonrefrigerated commercial or farm warehouses. This method of storing offers the primary advantage of orderly marketing several months after harvesting. After they are harvested, sweet potatoes should be cured. Do not wash sweet potatoes before curing. Curing promotes the healing of cuts and bruises that occur during harvesting and handling. It also protects the roots from storage diseases and excessive shrinkage while starches are being converted to sugars and other flavor components. Curing the roots increases the post-harvest life of the sweet potato. To cure roots, hold them at 85 degrees F with 90 to 95 percent relative humidity (RH) for 4 to 7 days.

After curing, reduce the storage temperature to 55 to 60 degrees F at 80 to 85 percent RH. Most properly cured sweet potato cultivars will keep for 4 to 7 months. Due to the sweet potato’s tropical origin, roots will develop chilling injury if held at temperatures below 54 degrees F. Short periods at temperatures as low as 50 degrees F will not cause damage, but after a few days at 50 degrees F or shorter periods at lower temperatures, sweet potatoes may develop flesh discoloration, internal breakdown, off-flavors, hard cores when cooked, and increased susceptibility to decay.

Temperatures above 60 degrees F will stimulate sprout development (especially when combined with high humidity), pithiness, and internal cork (a symptom of a viral disease) when the virus is present. Sweet potatoes are usually stored in bulk bins or slatted crates. Palletization of crates and the use of pallet boxes facilitate handling.

Sweet potatoes can be cured in palletized field boxes in a room designed to provide recommended conditions for curing. After curing, the sweet potatoes can be moved to rooms in which storage conditions are maintained continuously. Refrigeration is used in some large sweet potato storage facilities to extend the marketing season when ventilation alone will not maintain low enough temperatures.

Sweet potatoes are usually washed and graded, and sometimes waxed, before being shipped to market. Consult the USDA Standards for Grades of Sweet Potatoes for details on the sorting and grading of sweet potatoes at https://www.ams.usda.gov.

Roots can be treated with a fungicide to reduce decay during marketing. Consumer packaging of sweet potatoes in film bags or overwrapped trays is done to aid marketing and should not be done before storage. The shelf life of washed and fungicide-treated roots in consumer packs is only 2 to 3 weeks. Weight loss of roots during marketing is much less in perforated film bags than it is in mesh bags.

Well, don’t be discouraged because if you have an oven, then you can easily cure your own sweet potatoes there too. So you begin by putting a 40-watt bulb in your … via

How do you cure sweet potatoes indoors?

To cure the potatoes indoors, store them near the furnace, packed in boxes covered with a cloth to enhance humidity. Temperatures indoors generally range from 65 to 75 F. (15 to 23 C.), so a longer period of 2 weeks curing is recommended. via

How do you cure sweet potatoes with plastic bags?

In order to cure for long-term storage, sweet potatoes need high humidity and heat above 80 or 85 degrees for one to two weeks. To achieve these conditions, place sweet potatoes in a single layer in a plastic grocery bag. Tie the bag closed but also cut holes in the bag for ventilation. via

Can you eat sweet potatoes right after you harvest them?

You should resist the temptation to dig and immediately eat sweet potatoes, as fresh ones are more starchy than sweet, and don’t bake as well as cured ones. Wait at least three weeks before eating, so the starches can convert to sugars. Sweet potatoes can last six months or more in storage, if held properly. via

Should you wash sweet potatoes before storing?

If you are storing raw sweet potatoes, make sure you do not rinse them first. Rinsing could lead to rotting due to the extra moisture that is being introduced. Use a dry cloth to remove any dirt before you begin to store sweet potatoes. Another way to store raw sweet potatoes is to cure them for 1 to 2 weeks. via

How long does it take sweet potatoes to cure?

Allow roots to dry and cure before removing excess soil. Cure sweet potatoes by holding them for about 10 days at 80-85°F and high relative humidity (85-90 percent). In the absence of better facilities, they can be cured between 65-75°F for 2-3 weeks. via

Should you wash sweet potatoes?

You always—always—want to wash the skins before cooking or cutting sweet potatoes. It’s never a bad idea to give them a firm scrubbing with a clean vegetable brush, either. Sweet potatoes do grow in the ground, after all, and you don’t want any of that dirt or grit to end up in your finished dish. via

How do you preserve sweet potatoes?

Are sweet potatoes perishable?

Sweet potatoes are a highly perishable crop and difficult to store for extended periods of time. This is mainly due to their high moisture content, metabolic activity following harvesting and thin, permeable skin. via

How long do potatoes need to cure?

Cure newly dug and cleaned potatoes for a week to 10 days in a dark, well-ventilated area with moderate temperatures and high humidity, and they will last longer. After curing, slowly drop the storage temperature to about 40 to 45 degrees for table use. via

Do sweet potatoes come back every year?

Is a sweet potato vine an annual or perennial? Hardy in USDA zones 9-11, sweet potato vine is perennial in warmer climates, but is most often grown as an annual. via

How do I know when my sweet potatoes are ready?

Sweet potatoes 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. via

How long after harvesting sweet potatoes Can you eat them?

You can expect sweet potatoes to retain their quality for six to 10 months, but some cultivars may begin sprouting after six months. They will taste better if you give them a minimum of three weeks in storage to allow their starch to convert to sugar before you eat them. via

How do you make sweet potatoes last longer?

Refrigeration can diminish the flavor of sweet potatoes as well. Ventilation is another key to properly storing sweet potatoes—another strike against the crisper drawer. Instead, keep your sweet potatoes in a basket in a kitchen cabinet or basement. This is the best way to store them for longer lengths of time. via

How do you store sweet potatoes in the freezer?

How do you store potatoes long term?

The key is to store potatoes in a cool dry place, like in the cabinet of a pantry, in a paper bag or cardboard box. It’s important to keep potatoes at the cool, ideal temperature (but not, surprisingly, the fridge) to prevent them from turning green, getting soft spots, or pre-maturely sprouting. via

Do sweet potatoes get sweeter as they age?

Sweet potatoes, like fine cabernets, get better with age. But if handled properly, their starch converts to sugar and, when cooked, sweet potatoes live up to their sugary appellation. via

How many sweet potatoes do you get from one plant?

Sweet potatoes are grown from rootable cuttings, often called slips. If you’ve never grown sweet potatoes before, it can be great fun to grow your own slips from small or medium-size sweet potatoes purchased at the market. One sweet potato will produce between three and five slips. via

Last year I didn’t know to cure them before storage, and they were okay, but not that sweet, and they didn’t last very long before rotting. This year I’m thinking I’m going to give a lot away, and make a lot of freezable things too, so I’m not so worried about rotting, but I’d like to maximise sweetness.

The temperatures at the moment in the house are around 22C during the day and fall to around 12C some nights. The daytime temperatures are fine, but the night time ones not so much. We have central heating, but haven’t started using it yet, and I’d rather not. Also, to get high humidity, I was thinking I’d put the potatoes in the laundry/bathroom, but that’s one area of the house that doesn’t have heating.

We have a garage, but it’s unheated, and has a problem with cockroaches and spiders. I’d worry about leaving the potatoes down there because of the insects even if the temperatures are okay.

The internet recommends a covered porch (do not have), a sunny backyard (temperatures too low at night), or building a little greenhouse-like structure, or something complicated with crates and straw and a roof, none of which we have the building materials for, and which are going to work out to cost more than the potatoes are worth.

We also don’t own a space heater. (Some sites recommend putting one in a bathroom and leaving the potatoes in there).

We also don’t have any crates, racks or even any newspaper, which most sites think the potatoes should be spread out on. (I’m happy to buy newspaper, but not so much crates or racks for a few hundred potatoes).

Given all these constraints, is there any clever way to cure the potatoes? Will they be fine anyway if I leave them on the laundry floor in these conditions for a few weeks?

Could you staple them inside sheets of scrap cardboard and affix flat bundles of them to the surface of your water heater tank?

Assuming you have a water heater and its tank’s surface is in the correct temperature range and it’s not covered in fiberglass insulation or something like that.

(I have no potato-specific knowledge.)
posted by XMLicious at 10:44 PM on May 13, 2017

You could make a small cheap greenhouse with some shipping pallets and some Visqueen (polyethylene sheeting). A quick search shows some free ones available in your area on a site called gumtree. You may want to borrow some for a store so you will not have to store them or dispose of them when you are done. You probably want a minimum of 4 for bottom and three sides, but could use 6 to make a full cube or 5 to have one side open. You probably want to Visqueen the top and sides but leave the bottom open as you should get some heat out of the ground. You could put some earth from your garden around the base to help hold the heat in. The pallet on bottom will allow air to circulate.

If your clothes dryer vents out the side you could try to direct this into your greenhouse as this will put to use hot humid air that would go to waste. Do your laundry at night. You could put blankets on top at night to keep more heat in.

If you have a friend/neighbor with a space heater, you could barter the use of it for a few weeks for some sweet potatoes.

Keep in mind you are looking for a chemical reaction to happen, converting the starches to sugar. With higher temperature and humidity the reaction will happen more quickly, bit will still happen if you are at the lower limits, it will just take longer. And I am not an expert, but I assume if the temperature drops below the limits of the reaction, it will pause until it raises enough to resume, taking even longer.
posted by Yorrick at 10:59 PM on May 13, 2017 [3 favorites]

Response by poster: Good ideas. I don’t have a clothes dryer, and my water heater is outside and therefore extremely well insulated, so I think that won’t work either.

The small make-shift greenhouse idea is a great one. Unfortunately because I was overly enthusiastic I went and dug up the potatoes in the last couple of hours since I posted this question, and now it’s Sunday night and I won’t have time for gumtree sourcing of materials again until next weekend.

I have put them in a wheelbarrow for now. I’m actually wondering if that can be the basis of my storage system. It doesn’t let air circulate from below or the sides, but I could probably rig up a towel over the top with some gaps for ventilation, maybe. They are all piled on top of each other, though, not spread out in a single layer. Is that okay?
posted by lollusc at 12:09 AM on May 14, 2017

Fwiw space heaters are quite cheap (though running them for so long might not be).

How insulated is your kitchen? Do you cook a lot? If it’s fairly insulated cooking at night might keep it warm enough. Is it possible to keep things next to the side (or even back) of your fridge?
posted by trig at 1:14 AM on May 14, 2017

Where were you planning on storing them after curing? If you can just air dry the skins for 7 days or so they should be fine for a few months without any other treatment. I would leave them out in the yard in the shade under a tarp for a week. Slightly lower overnight temps aren’t going to ruin them, nor is slightly lower humidity.

Here’s some good info from U. Illinois in case you haven’t seen it.
posted by SaltySalticid at 7:36 AM on May 14, 2017

Sitting out in a cardboard box (protected from direct sun and rain) can do it as well.

Neighbor kept a shipping container at his plot (for tools etc), and would cure his sweet potatoes in it.

I use my open/unheated garage – laid them out on newspaper on a table for two weeks. Daytime temps were 80s/90s, night time 60s-70s, all but 2 kept over winter. Bugs/spiders left them alone, but we use our garage for car parking, etc, so it’s opened all the time.
posted by k5.user at 8:31 AM on May 15, 2017

  • I currently have sweet potatoes (technically yams) in the ground that are going to need to be harvested soon. As a newbie, it is to my understanding they need to be cured at about 90F in a humid place for about 10 days before they will acquire their sweet taste. What are some tried and true ways of doing this when you don’t have a space heater, let alone a small room to store the potatoes in to cure?

    I saw online some articles saying to do it in the oven. but is this reliable?

    I do have a small humidifier, just no heater.
    They’re beauregard yams.

    Hill Country Dream: Land Acquired > Home plans driving me crazy (still) > food forest pending