My wife and I love sweet potatoes. In fact, we love them so much that we eat everything we grow and still need to buy a fifty pound box of “Beauregard” potatoes from a friend that goes to Louisiana every November.
Sweet potatoes are delicious, versatile and nutritious. Photo by Bruce Leander
Now I have to admit, I have not always loved sweet potatoes this much. When I was a kid my family only ate sweet potatoes at “the holidays”. Our Thanksgiving and Christmas “sweet potatoes “ came in the form of a mushy, orange bowl of goo dripping in syrup and covered in baked marshmallows. Now you would think that with that much sweetness going for it, I would look forward to the holidays. Well, I didn’t. I hated this mushy mess (and so did everyone under 40 that I knew at the time) and it made me dread Holiday dinners. Even though I loved the turkey and dressing, ambrosia and pea salad, I knew it would all be ruined by that sticky, slimy mess that my mother would force me to eat.
I am not sure how or when it happened, but sometime in the past few years my opinion of sweet potatoes changed. Sweet potatoes have now become a staple in my (and many other Americans) diet. As interest in healthy eating has surged the popularity of the sweet potato has sky rocketed. And why not? Sweet potatoes are loaded with vitamin B6, vitamin C and vitamin D. They are also full of iron, magnesium, potassium and carotenoids like beta carotene. Plus, they are full of natural sugars (that make them taste so great when cooked properly) that are actually good for you.
Patty Leander plants here home grown sweet potato slips in her Austin garden. Photo by Bruce Leander
In my experience, the hardest part about growing sweet potatoes is finding them. Sweet potatoes are generally grown from “slips” (however they DO NOT HAVE TO BE, read my post on growing sweet potatoes from the actual potato). Slips are simply sprouts that grow out of a mature sweet potato. If you have access to a local producer/seller of slips you will have no problem. In my experience, it is getting harder and harder to find people who are willing to grow, harvest and sell their slips locally. If this is the position you find yourself in you have two choices – go to the internet and hope for the best or grow your own.
Slips are easy to grow, so I grow my own. Since we buy 50 lbs of Beauregards each year I always keep a few of those back for seed potatoes. You can do this with any variety you like. If you find a variety you like at the store keep a few back. If using store bought potatoes look at the skins closely. Some are sprayed with wax to extend their shelf life. If they have wax on them they will not sprout well for you. Look for unwaxed varieties if you want to use them for seed.
Sweet potatoes can be planted from March through July in in Central Texas. Photo by Bruce Leander.
Before we talk about how to grow your own, we need to discuss when to start growing them. Before you grow your slips you have to determine when you are going to plant them. In my Zone 9 garden I can plant sweet potatoes anytime between March 15 and July 4. Determine when you want to plant and then start your slips about six weeks before you want to move them to the garden. I like to plant my sweet potatoes a little later than most folks. I usually plant around June 1. To meet that planting date I need to start my slip production around the first of April.
I have had good luck making slips by placing tooth picks in the side of the tuber and submerging the bottom half of it in water. For best results place your tubers in a sunny location where they will be between 75 and 85 degrees. In a few days, the eyes will begin to produce the shoots that you will use as your slips. These shoots will grow straight up from tuber. When they are about 6” long snap them off with a twisting motion where they touch the sweet potato. If you look closely you will see little roots already beginning to form where the slip grows out from the tuber. Try and get those little roots when snap the slip off. Once you have harvested the slips move them to another container of water. In about a week, the slips in the jar will create a pretty extensive root system. Once the slips put on roots they are ready for planting. You can either move them directly to the garden at this point or you can pot them up and let them become established for later planting.
Sweet potatoes can easily produce three or four pounds of tubers per row foot. Photo by Bruce Leander.
While I have had success with the tuber in water method, I have had two problems with it. The first is rotting tubers. If you leave your potato in water too long it will become mushy and begin to stink to high heaven. The second issue has to do with the slips. If you leave them in water for too long the will grow an EXTENSIVE root system. When I have planted these overgrown slips I have not had good luck getting them to grow when I put them in the soil. Because of this, I recommend planting, or potting your slips soon after the roots begin to form.
Planting and Growing
Since sweet potatoes grow below ground, it is best to plant them in a loose soil. Sandy loam is perfect. Loose soil will allow them to get big and form attractively shaped tubers. However, the main reason you want to grow in loose soil will become very evident when you try and harvest them. It can be very hard to get the undamaged roots out of heavy soils like the black clay I grow in. If you don’t have sand or loam you can still grow sweet potatoes. Make beds that are about a foot tall and very well worked with compost.
Sweet potatoes produce lovely and lush edible vines. Photo by Bruce Leander.
Plant your sweet potatoes in full sun. Sweet potatoes are tropical vining plants. Because of this they love high heat and full sun. My beds run east to west so my plants can get the most sunlight possible.
I grow my sweet potatoes in a single bed that is 33‘ long and about 10’ wide. To plant my slips I drive a large screw driver into the center of the bed and swirl it around to make a hole about every 12″. I then drop the slip in and firm up the soil around it. Once the slips are planted I water every other day for a couple of weeks to ensure that those young tender roots get fully established before the heat of our summers really kicks in.
Once the sweet potatoes are in all you have to do is water and wait. These tropical vines will thrive on a twice a week watering schedule. Once the vines start spreading do not add any supplement nitrogen. Too much nitrogen will encourage the plant to make big beautiful foliage and small fibrous roots.
To grow the biggest sweet potatoes possible grow them in a loose soil. Photo by Bruce Leander.
Harvest and storage
Sweet potatoes take 100 to 140 days to mature fully. However, you can harvest them at any stage of their development. Once they reach that 100 day point start watching their foliage. When they are ready the leaves will begin to turn yellow and the vines will begin to look less full and healthy.
If you plan on storing your sweet potatoes you must dig them carefully. Knicks or breaks in the skin will encourage rot during storage. When you get ready to harvest take a garden spade and work it into the soil just beyond the end of the vine. Gently turn the soil over to expose your tubers. Pick these up and then continue moving toward the center of the row. Sweet potatoes can produce tubers anywhere along their vines. Because of this you will want to turn over all of the soil in the bed.
Sweet potato skins are tender. use a spade to carefully remove them from the soil. Photo by Bruce Leander.
When harvesting your potatoes do not wash them immediately. Separate the unblemished potatoes from those that have knicks or cuts. Go ahead and wash the damaged potatoes and take them inside. You will want to eat these first. Next, take the unblemished potatoes and lay them out in the sun for several hours to allow them to cure. When the roots come out of the ground their skins are very tender. Laying them in the sun will allow the skins to “set” or harden off before they go into storage. It will also dry out the soil that is still clinging to the tubers. Gently brush this soil off before moving them into storage.
Once you have cleaned your sweet potatoes spread them out in baskets that are lined with newspaper. Place them in a dry area that is around 85 degrees for a couple more weeks. At the end of this time the sweet potatoes are cured and can be stored for several months. Store your potatoes in a cool location that has high humidity. Proper storage will allow you to store your potatoes for several months.
Jalapeño Sweet Potato Soup
Sally and I eat sweet potatoes year round. Generally we cut them into fries and toss with peppers, onions, olive oil and spices and then bake them at 450 degrees for 30 or 40 minutes. However, each fall, we use them to make a soup that is ABSOLUTELY AMAZING! We got this recipe from our friends at Homestead Heritage in Waco several years ago. I highly recommend you make this soup. It is truly the best soup I have ever eaten!
4 lbs Sweet Potatoes
1 medium onion
3 slice smoked turkey bacon or ham
3 cloves garlic
8 cups Chicken Broth
1 tsp cumin
¼ cup pickled, sliced jalapeños
½ cup cilantro (leaves only)
1 ½ cups half and half
1 tsp salt
1 tsp black pepper
Optional sweetener to taste
*Scrub sweet potatoes, cut in quarters, place in large stock pan, cover with water and boil until soft
*When potatoes are soft drain them and let them cool until you can handle them. Peel of skins
*Peel and chop onion. Finely chop bacon or ham and garlic
*In large soup pot, melt butter. Add meat, onion and garlic and sautee until onions are translucent
*Add chicken broth. Cover and bring to a boil.
*Dice half of the sweet potatoes and stir into the boiling broth
*Puree the remaining sweet potatoes with the jalapenos, cumin, cilantro and half and half. Stir into soup. Add salt and pepper. Stir well, heat through.
* Taste. Add sweetener if desired