Written by Shawna Coronado
CI Leslie Caza with her sweet potato harvest
Did you know there are over 1,000 varieties of sweet potatoes (Ipomoea batatas) and almost all of them thrive in the heat? Even a super-hot summer won’t get the best of these herbaceous perennial flowering vines, so there’s no reason to shy away from planting sweet potatoes during our sunniest season.
Family Relations – Sweet Potato Kin
Sweet potatoes are not directly related to traditional potatoes. They are a member of the bindweed or morning glory family. In fact, their blooms resemble a morning glory flower. Although often referred to as a “yam,” a sweet potato is not a yam as it has deeper orange flesh.
Most sweet potatoes are surprisingly heat tolerant and drought resistant, preferring at least 16 weeks of a warm growing season. Although grown worldwide, sweet potatoes are a tropical plant. It is believed they originally came from Central or South America and were domesticated over 5,000 years ago.
Four to a Square (or Bucket) – Planting Sweet Potato Slips
Top Hat box ready to fill with Mel’s Mix
Plant your sweet potatoes where they will get the most sunshine in your SFG grid. Sweet potatoes are typically not grown from seed but grown from “slips,” which are sprouts that grow from the eyes of mature sweet potatoes.
When planting, snip off the lower leaves, keep the top ones on the slip, and make sure the sprout’s leaves are poking above your Mel’s Mix™. To give sweet potatoes ample room in your SFG bed, use a Top Hat box. This is a 1′ x 1′ box that’s 6 inches deep and is placed on top of a single square of your regular SFG box. Fill it with Mel’s Mix™ and now you’ve got a foot of grow space for your crops. Plant these four to a square; train the vines up a trellis. Or, plant four slips in a bucket so your vines won’t interfere with neighboring plants. Water generously for the first 10 days, then water regularly thereafter. Here’s a video of Mel with great advice on growing potatoes in a bucket: Video Link
Sweet Potatoes Do Not Like Frost
Plant this crop only when temperatures reach around 60 degrees Fahrenheit – about four weeks after the last spring frost. Make sure you give them 120 days of growing potential as it takes that long to grow good-sized tubers.
In my zone, 9b, I can plant slips until the end of September. But in the Midwest’s zone 5b, for example, slips should get in the ground no later than August as mature plants will wilt at the first sign of a cold night even if the days remain considerably warm. Sweet potatoes absolutely hate frost; you can extend the growing season by covering your potatoes at night with an insulating barrier to hold in heat.
How to Harvest Sweet Potatoes
It’s time to harvest when the ends of the vines and leaves begin turning yellow – around 95 to 120 days after planting your slips. Sweet potatoes can bruise, so gently pull them from your grid or bucket.
Curing Sweet Potatoes
Sweet potatoes must be cured before storing to enhance their flavor. Place the tubers in a covered location where the air is humid and around 80 degrees Fahrenheit. Be sure that the individual potatoes are not touching and let sit for about two weeks. Curing facilitates the growth of a second skin that will help close scratches and protect against bruising. Once cured, store in a cool, dry location. If stored in a root cellar or basement, the roots can remain viable for about six months.
Growing sweet potatoes in your SFG is incredibly easy; it’s a great plant to grow for the hot summer season in the north or in the late summer/early fall growing season in the southern states. With the ability to last up to six months in storage, this root veggie can offer long term savings and delicious side dishes all fall and winter for your family.
