Growing sweet potatoes can be an immensely rewarding experience that helps fill your pantry or winter CSA baskets. But a common refrain from farmers and gardeners in eastern Ontario is the uncertainty of sweet potato yields year-to-year.

Sweet potatoes are a 100+ day, heat-loving crop and eastern Ontario’s season is just long enough to get a marketable crop. A late frost that delays planting or an early fall frost that necessitates an emergency harvest can significantly impact yields. 

At Heartbeet Farm we’ve been growing and trialling locally bred sweet potatoes for six years Unique Sweet Potato Slips for Ontario | Heartbeet Farm. Most of our varieties come from a breeding project by Telsing Andrews of Aster Lane Edibles to increase the production of high-calorie storage crops in West Carleton (Ottawa’s rural west end). I was lucky enough to learn all about sweet potatoes from Telsing and eventually carry on the project. Here’s a bit about the work and some growing tips. 

Trialling locally bred sweet potato varieties

In 2019, with 60 potential new sweet potato varieties grown from true sweet potato seed at Aster Lane Edibles, I partnered with the Ecological Farmers Association of Ontario to grow them out and collect data. We then conducted a multi-farm trial in 2020 with the top 10 varieties EFAO-Sweet-Potatoes-2020-final-audio.pdf. Sweet potatoes were selected based on the number of tubers per plant, size of tubers, ease of harvest, skin smoothness, taste, sweetness and colour. Skin colours ranged from brown to red, pink and purple, and flesh colours included white, yellow, orange and purple. We also collected data on seed set since having varieties that set seed within our season is key for the continuation of the breeding project.

Today, I run Heartbeet Farm in North Augusta, ON with my partner David Mazur-Goulet. Together we grow 40 different vegetable crops organically for our summer and fall CSA programs and sell sweet potato slips in the spring. An exceptionally rewarding part of growing these unique varieties has been watching them spread across eastern Ontario and beyond as people continue to grow them year after year. 

Most slips grown in Ontario are shipped up from the United States. Our goal is to increase access to locally bred slips for home gardeners and eventually other farmers as we increase production.

Here are some growing tips that experienced growers have shared with us along the way:

  • Resist the urge to plant your slips until the soil is warm and nighttime temperatures are above 10C. Usually that is around the first week of June. Cold soil as the plant sets its roots will significantly impact shape and yield of tubers.
  • Plant into loose soil or you’ll end up with sweet potato sticks. If you have heavy clay soils, consider a raised bed.
  • Plant into clear or black plastic or under low tunnels. Putting the plastic down early helps to increase the temperature of the soil. Thicker plastic like silage tarp or vapour barrier can be used year after year to limit waste.
  • Water weekly for at least the first month while they’re setting their roots. Sweet potatoes are quite drought tolerant, but irregular watering while they are sizing up can cause cracking. 
  • Some sweet potato varieties size up significantly in the last few weeks of the season, so waiting an extra week or two can make a big difference. Start checking them in early September and harvest as soon as nighttime temperatures are below 10C for a week straight, or your vines get frost damage.
  • Sweet potato skin is very delicate until it has been cured, so be as gentle as possible during harvest. If using a shovel or fork, start loosening the soil at least eighteen inches away from the base of the plant to avoid damage. They can set roots quite far out.

Curing & storage

If you’re only growing a few sweet potatoes and plan to eat them within the month, you can just take them inside and keep them warm in your kitchen. If you are planning to store them over winter, they must be cured immediately. Curing also increases the sweetness. Sweet potatoes taste best one to two months after harvest and curing. The ideal curing environment is 28°C and 90% humidity for 10-14 days. Tarps, humidifiers, and fans can be very helpful; just ensure there is adequate airflow to avoid rot. Once cured, sweet potatoes should be kept above 14°C; a pantry, basement or kitchen cupboard works well.

Slipping sweet potatoes

Growing your own slips is incredibly easy. When you harvest in the fall, set aside a few medium-sized sweet potatoes without cracks or blemishes. In February, fill a tray with moist potting soil and lay the sweet potatoes down in the soil half buried. Place the tray on a heat mat or in the warmest place in your house or greenhouse. You should see sprouting within two to three weeks. If you do not see sprouting and the potatoes are still firm, it is not warm enough. Let the slips reach eight to twelve inches, break them off and root them in moist potting mix or a jar of water. A single sweet potato can produce more than a dozen slips. The slips will continue to grow once rooted and can be cut at a leaf node to produce more slips. 

Let’s grow more sweet potatoes

The vast majority of sweet potatoes consumed in Ontario are imported. But this long-season crop can and is being grown successfully by many farmers and gardeners. It is our goal to increase access to reliable, local varieties of sweet potatoes and slips in the Ottawa region and beyond. Some of the most common varieties grown commercially are Covington and Beauregard. The orange fleshed Candy Crush that we grow would be most similar to these. For small growing spaces we recommend our variety called Magenta. It has short, compact vines, purple skin and white and purple speckled flesh. See other varieties we grow at Sweet Potato Slips | Heartbeet Farm

We would love to hear from you if you have questions or ideas about growing sweet potatoes in Ontario. Hopefully you get to enjoy digging up big beautiful sweet potatoes for many seasons to come.


Kate Garvie

Heartbeet Farm

North Augusta, ON

Researching & Growing Sweet Potatoes in Eastern Ontario