Sweet potatoes (Ipomoea batatas) are tuberous, elongated root vegetables that come from a flowering plant. They are not to be confused with yams (Dioscorea sp.) which while also a tuber are an entirely different vegetable. Yams are native to Africa and Asia, and they are related to lilies while sweet potatoes originated in Central and South America, and come from the morning glory family.
Sweet potatoes are a relatively new crop to Canada and account for only 0.76% of all Canadian veg production with only around 2,000 – 3,000 acres planted each year.
There are many varieties of Sweet potatoes. The skin colour may be white, yellow, red, purple or brown, while the flesh may be white, yellow, purple, orange or orange-red. The Sweet potatoes with golden skin and paler flesh tend to be firmer and a little waxy after cooking while the sweet potatoes with copper skin and orange flesh tend to have a sweeter, creamier flavour.
Yams typically have a blackish or brown, bark-like skin and white, purple or reddish flesh. Yams are starchier and drier than Sweet potatoes, resembling yucca in texture and flavour.
Canadian farmers supply approximately one quarter of the Sweet potatoes consumed in this country. Most are grown in Ontario. A new variety called Radiance was recently developed for the shorter growing season in other parts of Canada, but it is not widely available yet.
How to Buy
Look for Sweet potatoes with tight, unwrinkled skins free of blemishes or bruises. Sweet potatoes become starchier as they grow in size so select small- to medium-sized ones.
How to Store
Do not refrigerate Sweet potatoes as this stops the sugar conversion process.
Store bought Sweet potatoes generally do not store long as they have been pre-washed and the outer skin has started to break down. At room temperature, they will last for about a week, but kept in a cool, dry, dark location with adequate ventilation, they will last for up to four weeks.
Bruised Sweet potatoes deteriorate rapidly and, once a sweet potato begins to go bad, you cannot just cut away the spoiled part since the decay affects the flavor of the entire sweetpotato.
Sweet potatoes are not ideal for freezing, but you can peel, slice and blanch them before placing them in freezer bags. Another option is to bake unpeeled sweet potatoes at 400 F for about an hour and wrap them in a single layer of foil after they have cooled down. Place the baked sweet potatoes in a freezer bag and squeeze out excess air before placing in the freezer.
How to Prepare
After washing, Sweet potatoes can be baked in their skin in the oven, microwave or barbecue. You can also peel them and boil, steam or grill them. Sweet potato fries are a popular alternative to conventional potato fries. Sweet potatoes also work well in curry dishes and as the star of soup.
Sweet potatoes are a super vegetable! A medium one contains more than 100 percent of the daily recommended vitamin A intake and 65% of the daily vitamin C intake.
Sweet potatoes are a great source of fiber, vitamins, and minerals. The orange and purple varieties are especially high in antioxidants that protect your body from free radicals.
One cup (200 grams) of baked sweet potato with skin provides:
How They are Grown
Interview with Phil Keddy, Valley Harvest Sweet Potatoes and Charles Keddy Farms
Besides a name, sweet potatoes share nothing in common with russet, yellow or other potato varieties you might be familiar with. Regular potatoes are a round tuber that grows from the roots of a plant from the nightshade family, like tomatoes, eggplants and peppers. Sweet potatoes are the fattened root of a vine from the morning glory family. They are visually nothing alike but both produce a starchy root vegetable with an outer peel and long storage life.
The Canadian sweet potato industry is relatively new and still small, with only around 2,000 – 3,000 acres planted each year. The majority of the crop is grown in the Norfolk County region of Southern Ontario but there’s also some production in British Columbia, Quebec, Manitoba and Eastern Canada. We caught up with Phil Keddy, owner of Charles Keddy Farms and Valley Harvest Sweet Potatoes in the Annapolis Valley region of Nova Scotia, to talk about his thriving sweet potato operation.
The Keddy farm dedicates 60 acres to sweet potatoes each year and because of Canada’s shorter growing season, they have to import vine slips from North Carolina to grow in their fields. “The sweet potato vine is a sub-tropical plant, and the Covington variety we grow needs 120 days to come to maturity,” said Phil. “There are some Canadian greenhouses growing sweet potato slips for commercial propagation but with their heating costs, their prices are just not as competitive as the ones we import.”
The slips are cut from the ground grown vines in North Carolina in June and spend three days on a truck being shipped to Charles Keddy Farms. By the time they reach Nova Scotia they have started to root and are planted by hand into hilled fields.
The Keddy farm also operates a large commercial fruit nursery where they propagate green topped strawberry plants, raspberry canes and blackberry bushes, as well as asparagus and rhubarb. Strawberries are another vining plant that propagates via slips (or clones). The Keddy’s plant and raise 24 million strawberry plants in 30 different varieties to pre-fruit producing stages each year. Then around June they harvest these green plants, and some of the varieties are sold to Canadian wholesalers, greenhouses and garden centers for consumers to buy and plant in their gardens.
About 60% of the Keddy’s strawberry production is shipped to commercial fruit producers in Florida where they are planted in the ground and continue on to produce strawberry fruits. Some of these strawberries are then shipped back to Canadian grocery stores for us to consume. “Canada’s cooler climate means there aren’t a lot of bugs or diseases that will hurt our strawberry plants when they are growing in those early stages,” said Keddy. “But we also don’t have a long enough growing season to produce the nice big red varieties that consumers enjoy, whereas Florida does.”
It is this experience in strawberry production that has made the Keddy’s foray into sweet potatoes such a success. Like strawberries, the Keddy’s prepare their sweet potato rows with 12 inches of fluffy soil, chicken manure, granular fertilizer and irrigation tubes before tarping the hills with black plastic. This plastic cover keeps the ground warmer and moist and protects it and the sweet potatoes from fall frosts. “This method of tarping the soil has increased the yield, size, quality and marketability of my potatoes by 50 percent,” Keddy stated. “It has really made growing sweet potatoes in Nova Scotia a lot easier.”
Sweet potatoes are the fattened root of the vine and require sufficient water and nutrients throughout their growing season to plump up. The drip irrigation system that is installed in the mounds also provides a liquid nitrogen fertilizer at the optimal time in the growing cycle to feed the roots. Since sweet potatoes are a relatively new crop to Canada, the Keddys have never had to spray their vines for pests or diseases. “Any bugs that come in on the slips from North Carolina are dead within a few cool nights in our fields,” said Keddy. “In 10 years of producing sweet potatoes we’ve never had to spray our crops for pests.”
Sweet potatoes have a relatively thin skin when they are first harvested, so bruise, scratch and damage easily. As a result, the Keddys hand harvest their 1.5 million pounds of sweet potato each fall between October 1 and 15. “Because of the strawberry operation and the large labour force we employ to harvest those plants, hand harvesting our sweet potatoes isn’t a big stretch and it fits well with the strawberry season timeline,” Keddy pointed out. They employ close to 80 labourers each summer, of which about 90% are through the Temporary Foreign Worker program.
After harvesting, the sweet potatoes are moved to a large storage warehouse that is outfitted with temperature controls and large fans. The bins full of sweet potatoes are left for 7 to 10 days in a heated, ventilated room to cure the delicate outer layer into the tough skin you see in the store. From there, Keddy lets his potatoes rest for a minimum of 3 weeks before washing, packaging and shipping to various vendors.
Unwashed sweet potatoes can store well in a temperature and humidity-controlled environment for up to a year and are one of the few vegetables that gets better with age. “They are continuously converting starches to sugars and as they dry out, those sugars condense,” explained Keddy, “so older sweet potatoes are sweeter than the ones fresh out of the ground.”
The majority of his marketable sweet potatoes go to retail grocery stores and the larger potatoes are sold into the food service industry. He’s been able to find a market for his smaller sweet potatoes by packaging them into 3-pound bags for thrifty grocery chains, but the rest of the crop that doesn’t meet consumers’ standards is fed to his cows. “Livestock eat the majority of the crooked, bent, cracked, scratched, or damaged sweet potatoes that can’t go to certain food grade markets,” said Keddy, “but food waste is a major problem, so we are working on some different uses for unwanted potatoes.”
Although Canada only produces 2,000 to 3,000 acres per year, we supply about 25% of the Canadian market. The rest come from the United States, where North Carolina is the country’s top producer, with 1.7 billion pounds of sweet potatoes grown in 2020.
Canadian Crop is Available: October to September
Grown in: Ontario, British Columbia, Quebec, Manitoba and Nova Scotia