You’ve sweated and toiled all summer caring for your sweet potatoes in the garden, or maybe you’ve grown sweet potatoes indoors. You’ve lovingly protected your plants from powdery mildew, stem rot, and sweet potato weevils. You were careful to harvest sweet potatoes gently, so they didn’t have any cuts or bruises, and now, it’s time to eat… almost. You could certainly eat them right after picking if you really wanted to. But if you have a lot, don’t let them go to waste by not properly curing your sweet potatoes. Curing sweet potatoes ensures that they have the right texture, taste just as sugar-sweet as you want them, and last you through the winter. If you love sweet potatoes, you’ll want to be prepared to take this step!
Curing sweet potatoes is essential to getting the most out of your tubers. Curing is a process that will transform your produce by extending shelf life, preventing rot, and improving flavor and sweetness in the case of the sweet potato. During this curing process, you create the ideal conditions to transform your produce by adjusting the temperature, humidity level, and at times light exposure.
Storing is not the same as curing, and often the conditions for the two are very different. Each vegetable has different curing needs so be sure to do additional research because here, we will only be going over how to cure sweet potatoes. But we have an excellent article on harvesting and storing sweet potatoes that you should read, too!
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All About Curing Sweet Potatoes
Homegrown sweet potatoes are still alive even after being harvested and need oxygen. They are still undergoing a transformative process after harvest where starches are converted to sugars, impacting the overall taste of your sweet potato. A successful curing period will result in a signature tasty sweet potato. The initial curing process also allows sweet potatoes to heal any scratches or bruises that happened during harvesting.
Before we talk about the curing conditions of sweet potatoes, it is essential to note that you should not wash your sweet potatoes before curing them as this will shorten their life and give you a less successful cure. You can gently brush any remaining dirt after the sweet potatoes were harvested.
Sweet potatoes initially need heat. Aim for high temperatures between 80-85 degrees when curing sweet potatoes. The initial curing process takes 4-10 days. When your tuber feels firm and moist, it is done curing and ready to undergo the rapid transition to cooler temperatures. If they’re still soft to the touch, it may be best to enjoy the flavor of that sweet potato rather than spend more time trying to perfect the cure.
You can store your cured sweet potatoes at 55-60 degrees, but no colder than that, as the cured sweet potatoes are sensitive to cold temperatures and could develop a chilling injury. However, this is a delicate balance because temperatures higher than 60, combined with high humidity, can cause sprout development.
Sweet potatoes need a humid environment when curing as well as in storage. During the curing process, be sure to maintain a 90-95% humidity level. Make sure to have ventilation to allow the hot, moist air to move around while they are in there. When shifting to long-term storage, you will still need to aim to maintain a level of 85%.
Creating these circumstances for a curing location can be tricky for some people, especially home growers. But it shouldn’t be something you skip because it is difficult. The difference in taste alone between a cured and uncured sweet potato is enough motivation to go the extra mile and get creative. Below are some ideas to get the ball rolling.
- In the greenhouse: Greenhouses can be an excellent place to cure your sweet potatoes for those who have one. You can easily monitor and control the temperature and moisture level of your greenhouse. For some regions, it may be too cold to cure these during the later harvest months unless you have a climate-controlled greenhouse, but if you do, this is a great option.
- In a bag: You can easily cure your sweet potatoes in a plastic bag to create humidity. After placing a handful of sweet potatoes inside, tie the bag closed and cut a few holes in your plastic grocery bag for a little ventilation. You can then place your plastic bag either in a warm sunny spot in your house or in a small closed room with a space heater. This is a great, affordable option, but it can be difficult and time-consuming if you have a lot of sweet potatoes to handle after harvest.
- Use a humidifier in a confined space: If you don’t want to go the plastic bag route and have a humidifier, this is an excellent option. Place your humidifier and space heater in a small closet or even a shower stall with your sweet potatoes. It needs to be a closeable space so that the damp air stays trapped inside. Depending on how long and how many sweet potatoes you are harvesting, this might not be a great option if you need to use that shower or closet during this period.
- Consider a grow tent: A grow tent is a great option to produce cured sweet potatoes. Add in some grow mats on each shelf to create heat along with a humidifier, and this is probably the most seamless way of curing sweet potatoes if you have enough space for a grow tent.
- Near a bucket of water: I have personally used this method for a couple of years before buying a humidifier for some of my houseplants, and it worked great. Placing a bucket of water in a warm, confined space near your sweet potatoes adds moisture to the air and creates humidity. However, this is not a long-term solution to storing sweet potatoes afterward. When you need to decrease the temperature after the sweet potatoes have been cured properly, the bucket of water will no longer generate enough humidity, and your tubers could be easily damaged.
- In the oven: You can even use your oven to cure your sweet potatoes. Some will use a low-temp oven, but all you need is an oven with a warm light. The light from the oven generates enough heat that it can reach the needed temperatures in the small enclosed space. For humidity, place a pan or oven-safe container at the bottom of your oven with water inside. Once you are within range, put trays of sweet potatoes inside your oven and place a wooden spoon or something close to that size in the door to keep it open a crack so that the heat doesn’t keep rising.
Some of these suggestions are more difficult to control the heat and moisture for curing after harvesting sweet potatoes. These variations in temperature and humidity mean that your curing timeline may not be universal. A slight cool in temperature will result in a longer curing time and vice versa. Check the sweet potato for a firmer skin to know that they are ready.
Once you’ve completed the process of curing your sweet potatoes, tuck them into the root cellar or a dark location in a single layer. If you don’t have a root cellar, store them somewhere dark, cool, and moist (and check out our article on harvest and storing processes for other suggestions). If stored properly and in a cool enough location, you’ll have stored sweet potatoes awaiting use for months!
Frequently Asked Questions
Q: Do sweet potatoes need to be cured before eating?
A: Technically, curing is not necessary. You can pick these tubers off the vine and eat it that same day; it will just be missing out on that signature sweetness. We highly recommend you cure and store sweet potatoes so the starch has a chance to turn into sugar, giving them that great flavor and increasing their shelf life.
Q: How do you cure sweet potatoes in the oven?
A: There is a more detailed explanation above. Make sure you have a low-temperature oven, set it to a “keep warm” cycle, or use one with a warming light. You will also need an oven-safe pan to put water in and something to prop your oven door open a crack to be sure your roots do not accidentally cook.
Q: Can you leave sweet potatoes in the ground over winter?
A: This depends on where you live, but for the most part, no. Sweet potatoes are not tolerant to cold temperatures, and although soil can provide some insulation, it’s typically not enough. Frost will damage the roots, and chilling injury occurs when soil temperatures drop below 50 degrees, resulting in internal decay. Use a digging fork to gently harvest your potatoes from your raised bed or other garden space, brush off most of the soil from the dangling roots, and protect your harvest before the first frost hits. When the weather once again gets warm, you can put the roots back out in the garden to start new vines.