What you see: Purple sprouts and stalks emerging from your sweet potato
What it is: A sprouting sweet potato
Eat or toss: Eat! A sweet potato with a small bunch of sprouts will still taste fine. Fresh sweet potato sprouts are edible too (unlike regular potato sprouts).
Yumi R. of Washington, D.C. forgot about this sweet potato on an open shelf, discovering two weeks later that it had sprouted a crown of little purple vines.
Like Yumi, you may be concerned about such a sweet potato, especially if you’re aware that when “regular” potatoes (say, Idaho russets) produce sprouts this size, you definitely want to cut them off. Potato sprouts contain toxins that can sicken people.
Sweet potatoes are totally different than potatoes!
But, sweet potatoes, despite their name and appearance, come from an entirely different plant. Sweet potatoes are thickened storage roots, cousins to morning glory flowers. Potatoes, by contrast, are underground “thickened stems” and are more closely related to tomatoes and eggplants.
No toxins here
So, great news for Yumi and her purple moptop root! Louisiana State University horticulturist David Picha assured me that not only are sweet potato sprouts free from dangerous loads of toxins, they're also edible. Sprouts like these may not be culinary stars, but chop up the purple bits and they could add crunch to a salad or blend into a stir fry. (And full disclosure: we haven’t sampled them yet ourselves, so if you do taste them, let us know how it goes.) Just make sure the sprout is still tender. They toughen up with time.
If you’re just looking at a small bundle of fresh sprouts like the ones pictured above, the sweet potato itself is also still fine to eat. Don't wait too long though. Developing sprouts drain nutrients, sugars and water from the roots, ultimately leading to dry, pithy sweet potatoes.
So what caused it to sprout?
The “local weather” in Yumi’s kitchen! After a couple of weeks at about 70 degrees Fahrenheit, a sweet potato’s biological clock will say, "Hey! It’s time to sprout!" At higher temperatures, that clock ticks faster.
A sweet potato will not sprout if it’s stored between 55 and 57 degrees, a range that would hardly be possible (or worthwhile) for the average home cook to try to replicate. A root cellar might come close. But a fridge is too cold for sweet potatoes and will mess with their flavor and texture—don't do it!
Little sprouts or tender leaves?
Eating this fresh sprout is a fine option. But Picha notes that it’s a small amount of food and the nutritional value of the fresh sprout won’t be as high as the leaves it might one day develop. If you want to give up on eating the root, Picha suggests burying the potato horizontally in moist potting soil and leaving it in a container in a sunny, warm (75 to 85 degrees Fahrenheit) spot. In a few weeks you should have some tender leaves ready for harvest.
Picha’s lab found that sweet potato greens are high in vitamin B6, as well as vitamin C and other nutrients. Nutritionally comparable to spinach, they're said to be great in salads. In certain regions in Africa and Asia, people often eat sweet potato greens, and since they can be harvested repeatedly without disturbing the potatoes, the plants make for efficient and nutritious land use.
For inspiration on cooking up your very own sweet potato greens, check out these ideas from Better Homes and Gardens and Tufts! Let us know how it goes!
David Picha. Professor of Horticulture. Louisiana State University.
Brandon K. Parker. Extension Agent - Commercial Horticulture. North Carolina Cooperative Extension Service
Sweet Potato. Vegetable Produce Facts. Post Harvest Center - University of California. Marita Cantwell and Trevor Suslow. Department of Plant Sciences, University of California, Davis
Sweet Potato. Home & Garden Information Center. University of Maryland Extension.
Can you eat sweet potato leaves? Introduce this leafy green into your diet. - by Rhys McKay. 16 DEC
2019. Better Homes and Gardens.
Wilmer A. Barrera, David H. Picha. Ascorbic Acid, Thiamin, Riboflavin, and Vitamin B6 Contents Vary between Sweetpotato Tissue Types. HortScience, November 2014
Nutritional and Medicinal Qualities of Sweetpotato Tops and Leaves. Shahidul Islam Professor Plant Science. Cooperative Extension Program FSA6135 University of Arkansas at Pine Bluff
Sweet Potato Greens. Sustainable Farming Project. Tufts University.
Growing Sweet Potatoes in the Sacramento Area. Cooperative Extension-Sacramento County. Environmental Horticulture Notes. University of California Agriculture and Natural Resources. October 2017, updated. May 2017 revised, February 2014, written by UCCE Sacramento County Master Gardener Gail Pothour.
Mechanism of Hardcore Formation in Chill-Injured Sweet Potato (Ipomoea batatas) roots. R. W. Buescher, M.R. Balmoori. Journal of Food Biochemistry. March 1982
If you find the twists and curls on the sweet potato pictured above impressive, check out Yumi's calligraphy work! Just as she loves applying creative energy to reducing food waste, she's passionate about artistry with paper and ink. Check out her calligraphy and penmanship on her website and instagram. Contact Yumi for custom projects such as letters, envelopes (events, weddings, etc), cards, and quotable quotes.