Produce Spotlight: The Ultimate Guide to Sweet Potatoes

Whether used in a side dish, baked into a dessert, or served as the main attraction, sweet potatoes are incredibly versatile and a great addition to any meal! You may be wondering how to grow them How long should they cook for? How do I prevent them from browning? In this month’s produce spotlight, we will discuss all these delicious details, recipes and more!

Sweet Potato Recipes

Origin and Growing Information

Origin

The earliest record of cultivation was over 5,000 years ago in Peru, and other parts of South and Central America. Their popularity began to spread in the 16th century following the discovery by European travelers.

Sweet Potatoes belong to the morning glory family, Convolvulacea. It is a common belief that sweet potatoes are just a type of potato, however, the two are classified slightly differently. 

Although both are enlarged storage organs that grow underground, sweet potatoes are modified lateral roots, or root tubers, while a traditional potato is a stem tuber. Root tubers are swollen secondary roots. Stem tubers grow from swollen stems, either rhizomes or stolons.

Varieties

Each variety possesses different characteristics including skin and flesh color, size, texture, and firmness. Here is a list of the more popular types and their identifiable qualities:

• Beauregard – red to copper skin and bright orange flesh 
• Jewel – copper to brown skin and orange flesh 
• Garnet – red to purple skin and orange flesh 
• Hannah – tan skin and white flesh that turns yellow when cooked 
• Okinawa – brown skin and purple flesh 
• Charleston – dark purple skin and purple flesh 
• Murasaki (Japanese Sweet Potato) – purple skin and white to yellow flesh

Growing Climate

Sweet potatoes do well in warmer climates where the growing season is predictable, however, with the right preparation, they can be grown in northern regions as well.

If you live in a colder state, such as Vermont, consider covering the beds with fabric mulch or plastic prior to planting to heat up the soil. Check out The Old Farmer’s Almanac for more tips on growing.

Growing Tips

This particular root vegetable grows from slips. Slips can be purchased at garden or seed stores, but it’s also super simple to grow your own!

To do so, you’ll cut a sweet potato lengthwise, and place the halves into warm moist soil. The potato will start to sprout small roots which can be cut and placed into a separate pot until ready to be planted (about 6 weeks).

You can learn more about buying or growing slips on Urban Farmer. 

Growing Conditions

The plants thrive in full sun and soil with good drainage, such as a raised bed. This placement keeps the soil warm and prevents rot. Roots need ample room to grow and splits should be placed 12-18 inches apart.

It’s best to plant the slips when the soil reaches 65°F and when the threat of a late frost has passed. The crops should be watered weekly, and more heavily during the dry weeks. 

Harvesting Tips

The roots reach full maturity in 85 to 120 days. It’s best practice to check in around the 85th day since root vegetables continue to grow and the skin can split if they become too large. Yellowing vines signals that they are ready to be harvested. The harvest should always happen before the first frost.

The roots will be 4-6 inches below the soil. Try using a tool to dig them up and shake off any excess dirt. In order to maximize the flavor, you’ll need to cure them by allowing them to air dry for about 10 days at 75-80° F.

Plant Hardiness

Sweet potatoes are only hardy in USDA plant hardiness zones 8-11. If you live in a moderate to cold region, the vines won’t survive the winter. This map will help you determine which zone you live in.

Yams vs. Sweet Potato

While many use the terms interchangeably, yams and sweet potatoes are entirely different crops. When first cultivated, growers and consumers needed to differentiate between the soft and firm varieties and since the softer varieties resembled a traditional yam, it became common to describe them as such. Yams are tubers, not true root vegetables.

In the US, fresh yams can be difficult to find in a normal grocery store, while sweet potato varieties are sold and consumed year-round.

There are different qualities that make the two distinguishable. A traditional yam has rough, scaly skin that is similar to bark and difficult to peel. The flesh of a yam varies from white to purple and the internal texture is starchier and drier than that of a sweet potato. They also do not offer the same nutrients as sweet potatoes.

Read more about yams vs sweet potatoes at the Library of Congress.

Nutrition Information

Nutrition Highlights 

All varieties are rich in micronutrients. They contain vitamin C, B6, and the minerals potassium and magnesium which both can reduce the risk of heart disease. More information can be found in The Journal of Clinical Hypertension.

Orange varieties contain beta-carotene; a provitamin that converts to vitamin A in the body. The National Institutes of Health states that vitamin A plays a role in normal vision, immune function, and reproductive health.

Purple varieties contain Anthocyanins. This type of phytochemical is known to work as an anti-inflammatory and anti-cancer agent by providing antioxidants and protecting the body from free radicals.

Calories

A medium sweet potato (5″ in length) is about 112 calories. According to the USDA, it contains 26 grams of carbohydrates, primarily starch (about 60% of the carbohydrate makeup), sugar, and fiber. Fat and protein content are relatively low and provide only 2g and .1g, respectively.

Sweet Potato as Baby Food

The high nutrient content and soft texture make them a great option for young ones. Once your child begins complementary feeding, it’s safe to introduce sweet potatoes that have been cleaned, peeled, and mashed or pureed to a smooth consistency.

This article discusses starches during complementary feeding in more detail.

Sweet Potatoes and Muscle Building

There isn’t a ton of scientific research that links bodybuilding and sweet potato intake, however, the carbohydrates present can be a good source of energy when sustaining long workouts.

Sweet Potato FAQs

Cooking Information

Prevent Browning

Once the flesh is exposed to the air, it begins a process called oxidation. To prevent this, begin cooking immediately after peeling or store them in cold water until you are ready to use them.

Preperation

The cooking time varies depending on your method. 

• Roasting: For roasted sweet potatoes: cut into ¾ inch chunks, toss with oil, salt and pepper and cook at 375°F for 35-40 minutes, or until potatoes are tender and browning. 
• Baking: Bake at 425°F for 50 minutes to an hour, or until fork tender. Because they weap while baking, it is best to put them on a foil lined baking sheet. It is not necessary to poke them with a fork.
• Microwave: Pierce 4 sweet potatoes all over with a fork. Microwave 8 minutes. Check for doneness by inserting a fork into the potatoes. Turn over (use oven mitts) and continue microwaving 8 to 10 more minutes. A fork should be able to slide into the flesh easily.
• Steaming: Peel and cut them into 2-inch sized cubes, bring 2 inches of water to a boil with a steamer basket on top, add cubes, cover, and cook for about 20 minutes.  
• Boiling: Clean them and cut them into evenly sized chunks. Bring salted cold water to a boil and add the potatoes. Leave on medium-high heat for 20-30 mins or until pieces are tender. 

Sweet Potato Casserole

The sweet taste, creamy texture and orange color is what makes a classic sweet potato casserole distinct. The Garnet, Jewel, or Beauregard have a higher sugar content and a soft consistency so it’s best to look for those when preparing a casserole dish.

Freezing

Cooking (boiling, steaming, roasting) prior to freezing them will help them keep their taste and texture. Be sure to let them cool off completely, and keep them in an airtight container before placing them in the freezer.

Shelf Life

Root vegetables tend to have a longer shelf life than their more perishable counterparts. Sweet potatoes should stay dry and cool but avoid storing them in the fridge. When kept at 55-60°F, they can last up to 6 months.

Storage

Sweet potatoes are safe to eat as long as they are firm to the touch. If your potatoes start to sprout, simply remove the sprouts before consumption.

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