Sweet potatoes, perhaps; yams, no. Yams (Dioscorea alata) cannot grow on the Canadian Prairies – they are native to Asia and the Caribbean (where they are a perennial vine) and require a very long growing season to be able to produce tubers.
Under certain conditions we might be able to grow sweet potatoes (Ipomoea batatas), which are sometimes mistakenly called yams (at least in the grocery stores, where the names seem to be interchangeable). Due to our short growing season, sweet potatoes are a tricky crop to grow, as we often run out of time to produce tubers. There are short-season types available, however. Cultivars such as ‘Covington’, ‘Beauregard’, and the Canadian-bred ‘Radiance’ can produce crops in 110-120 days, and ‘Frazier White’ supposedly only needs 105 days. This is, of course, if conditions are suitable. Due to the time constraints of our growing season (for example – Calgary only has 117 frost free days on average), starting the slips (unrooted vine cuttings) indoors is essential.
Sweet potatoes also require a long period of hot, dry weather to produce decently-sized tubers, and we all know that the weather doesn’t always co-operate in that regard.
If you have the heat and the time, sweet potatoes aren’t massively demanding plants, as far as inputs go (they are susceptible to a number of pests and diseases, however). They don’t need extremely rich soil; in fact, too much nitrogen is detrimental to tuber production. Beyond watering consistently, you don’t have to do much to make this crop happy. Sweet potatoes fare best in full to part sun, and will produce sizeable vines that resemble those of another plant in the same genus: morning glories (I. purpurea).
Although things will likely change in the future as breeding efforts continue, sweet potatoes are considered a novelty veggie on the Prairies (although they are grown as specialty food crops in provinces such as Ontario). You can attempt to grow sweet potatoes in-ground or in a raised bed, but your best bet is probably to try them in containers in your greenhouse and see what you end up with – at the very least, you’ll have a lovely vining plant to enjoy all summer!
Do you grow sweet potatoes in your garden (I’d love to know – whether or not you live in Canada!). If you enjoy eating sweet potatoes, what are your favourite ways to prepare them or use them in recipes?