My first job was working two summers during high school at a sweet potato farm just over the county line in McConnell, Tennessee. Mom got me the gig. Fred’s Plant Farm was owned by one of her co-workers, and he was looking for weekend and summer help. Every Saturday morning till I got my license Mom drove me to work. It was hot work, but as I reflect on those sultry days, I have fond pastoral memories of working on a farm.
The plant farm's claim to fame was once having their sweet potatoes mentioned on the Martha Stewart show. It wasn’t the large storage roots we dug each fall that Martha had mentioned. No, what she had purchased were sweet potato slips, short adventitious shoots that arise from the storage root. These were the mainstay of the company and easily shipped across the country to tv mogul and master gardener alike. Selling large sweet potato roots in rickety wooden bushel baskets was just a bonus.
Before I arrived, I knew very little about this root vegetable that thrives in our southeast weather. At the time, I didn’t even like sweet potatoes. But working on the farm gave me a great crash course of how to cultivate this southern staple. To produce the slips, we erected wooden beds about 10 feet wide and 100 feet long initially in a hoop house and then built them outdoors once it warmed enough to pass the fear of freezes. We leveled the soil, poured the sweet potatoes in by the bushel, and then topped them off with four inches of fresh sawdust. As the sawdust heated, it nudged them along into sprouting.
Sweet potato slips grown in a bed of sawdust. The propagules are pulled, bundled, and shipped around the country.
We waited I don’t know how many weeks for the shoots to emerge in the cool spring. I was so eager to see the little tops push out of the substrate I dreamed one night that I walked into the hoophouse and discovered hundreds of them sprouting. The next day at work, lo and behold I found some emerging. After they appeared was when the real work began. We would spend hours pulling sweet potatoes in bundles of 50. These would be packaged and shipped off. The last of the batch would become our starts for the fields. Once planted, they grew until harvested in autumn and then were stored over winter until the whole process would repeat again the following spring.
Sweet potatoes growing in a field just outside Martin, Tennessee. These will be harvested and used for next year’s starts.
Ten years later, I’m growing sweet potatoes again. But, now I LOVE LOVE LOVE these sweet and nutritious delicacies: sliced and diced with cajun seasoning, mashed with butter and salt, or in sweet potato casserole (or as my friend Stewart Thomas calls the dish butter and brown sugar casserole with a bit of sweet potatoes). The casserole was what converted me. A recipe my mom found won 1st place at a cooking contest in Tennessee, and it didn’t rely on any of that extra marshmallow or raisin fluff.
As much as I love them, it can be hard to find slips every year to purchase, and sometimes they can be quite expensive. Sweet potatoes are an asexually propagated crop. Most organs that we store as vegetative propagules like sweet potatoes, Irish potatoes (which is a swollen stem, not a root), garlic (which are swollen leaves, not a root), and the like we don’t store as seed. These fleshy organs are still metabolically active whereas many seed are dormant or in a resting state just waiting on water. Therefore, they won’t keep as long as say those tomato seeds from five years ago in the back of your fridge. That’s why they must be constantly regenerated. Hence the need to go slip to root to slip.
To get slips I took a lesson from my farm experiences as a teenager, and I grow my own. First, I propagated a few at SFA and watched students enjoy learning how to start the little slivers. I got my starts for school a few summers ago from George’s Plant Farm in Martin, TN. Funny that the one place I could find several different varieties available in the whole country was only about 30 minutes from my Tennessee home. We planted them out, and the following fall my Fruit and Vegetable Production class harvested over 90 lbs of sweet potatoes. We averaged 1.6 lbs for ‘Beauregard’ and 0.6 lbs for ‘Purple Passion’.
A sweet potato slip grown by a student at SFA. Probably named so because they slip right out of the substrate with a nice jerk from above.
After harvest, I had the students grade the sweet potatoes into large and small roots just like we did back at the farm. The large ones we sold in our garden market, and the small ones we stored in our classroom for forcing later in the spring. When time came the next year, we used four-inch-deep nursery trays to start our slips. We covered them with potting substrate, placed the trays in the greenhouse, and less than a month later the shoots were ready to pull. If left too long, you could quickly see where the genus gets the name Ipomoea, which means worm-like. The shoots will grow and wriggle all over the table even from the little bit of soil in the tray.
Once slips are pulled, a quick jab and pry forward and back with a sturdy shovel makes a good planting hole. We stick the shoots in, and they form roots very quickly. Well, let’s be technical. The latent roots already in the stem emerge quickly. That’s right, sweet potato stems have roots up and down their length as does tomatoes, coleus, and willow that enable them to quickly gain purchase to new soil or if damage occurs to the stem. Cuttings I’ve taken in the past put out roots within two days in water.
This year at my house, I’ve played around with making starts, too. I took some leftover ‘Beauregard’ and ‘O’Henry’ sweet potatoes we purchased, nestled them just under the soil, covered them with a few inches of leaf mold, and less than two weeks later I saw wee little shoots poking out. After they got a few leaves on them, I pulled them out of the ground, and stuck them into a bed. They’ve grown beautifully over the summer excluded from deer by our double fence that surrounds our patch.
Sweet potatoes are excellent soil covers as you can see in the image above. If you can keep them clean early on, they will seal their canopy and prevent weeds from germinating. However, I left the Rhus seedling in the back right corner to be moved to our prairie.
This past week marked approximately 100 days since planting, and the fresh rains that have fallen loosened the soil. Time to dig sweet potatoes! I cut the foliage off and carried it to the compost pile. Then, with the pitchfork I jabbed straight down into the ground careful not to puncture the storage roots, pried the swollen treasure out, and moved down the bed to unearth more. After all were dug, I gave them a light rinse from the hose but not a scrub. You don’t want to remove too much protective waxes from the root. Now, they have been sitting outside for a week elevated to protect from hungry rodents. This practice helps the wounds heal over. In the next day or so, I’ll move them inside. The small ones I’ll keep for next year, and the big ones I’ll eat.
Thar she blows! You know you’ve got something under the ground when you see the soil around the stem bulged up.
The swollen roots of ‘O’Henry’ sweet potato. Getting them out all still attached to the plant is an art in produce transportation.
My table runneth over with sweet potatoes. ‘Beauregard’ on the left and ‘O’Henry’ on the right.
And, oh will I eat them! I’m ecstatic about our harvest this year. ‘Beauregard’ is an old favorite of mine so I’m thrilled to have a good supply of this orange fleshed variety, and ‘O’Henry’ is supposedly a white-fleshed mutation of ‘Beauregard’. It’s yield was about 50% more than the ol’ Beau. So, if it tastes as good, I may have found another favorite variety.
One final note as far as cooking goes. You can enhance the sweetness of them by starting them in a cool oven. The enzyme that converts starch to sugar has more time to act if you start them cold than if you pre-heat the oven. Cause if you’re going to grow sweet potatoes, why not make them as sweet as can be?