Sweet potatoes are grown from plantlets called slips. Slips can be ordered online or easily grown at home. Photo by Joe Urbach
Growth in Gardening: Start Thanksgiving meal planting now
Start Thanksgiving meal planting now. Yes, I know how silly that sounds but I am serious. I am not suggesting you plan and plant the entire meal now; I am just talking about the sweet potatoes this week.
A staple of the southern fall diet, the sweet potato is scrumptious, nutritious and easy to grow. I know that most folks recommend planting the vines, called slips, in April, but I usually plant mine around May, or even June and then just let them grow all summer for an early fall harvest. I have planted these beauties in the ground, in raised beds and in pots, and I really liked the ease of harvesting the pots best of all.
Sweet potatoes are a part of the morning glory family so when you grow your own you get to enjoy the lovely purple flowers and beautiful, vigorous green vines while you wait for your sweet fall treat.
As an added bonus for growing your own, you can also harvest leaves as the roots grow, because those leaves are abundant and are a great source of nutrition. You can toss the leaves in with other salad greens or sauté them like spinach for a new summer green.
Now for the age-old debate, are yams and sweet potatoes one in the same? The answer is, no. While sweet potatoes are part of the morning glory family, yams are more closely related to lilies and grasses. Yams have brown skins with white flesh, are native to Africa and Asia, and vary in size from about a quarter pound to over 100 pounds. There are over 600 varieties of yams and 95% of these crops are grown in Africa. Compared to sweet potatoes, yams are starchier, drier and less nutritious. Sweet potatoes on the other hand range from white to yellow, red, purple or brown. The flesh also ranges in color from white to yellow, orange, purple, or orange/red. They are what we are familiar with eating. The true yam is not commonly found in the North American market and most Americans have never eaten a yam.
Now that that’s settled, let’s learn to grow our own sweet potatoes. Sweet potatoes are grown from plantlets called slips. I rarely see the slips/plants in any nursery, but you can order them online or better yet, it’s easy to grow your own. To get slips, simply purchase an organic sweet potato, sit it in the pantry and wait for vines to start growing. Snap these vines off and place them in water on a sunny window to begin rooting. Roots will form in just a few days. After the roots reach several inches or so, plant them in a pot or in the ground.
Another way to grow leaves quickly is to simply put a sweet potato, pointy side down, in a jar of water. Make sure a couple of inches of the tuber is covered by the water. You can stick toothpicks in the sides of the potato to hold it up if the mouth of the jar is too wide. Place the jar in a sunny window and wait for the vines to start growing. Snap the vines off just like in the first method and root them in water.
Once you get them growing in the garden, they are almost carefree. Depending on the variety, leaves will grow 2-4 inches wide and the vines will grow rapidly. Give them space because they can certainly fill it.
Now, this next bit is important. Once the vines get going, start tucking areas around leaf joints underground or into nearby pots. These will start to form roots which will lead to even more potatoes. If you want to get oodles of potatoes, keep tucking the vines every couple of feet or so.
I had great fun a few years back doing this. I ended up getting over 120 nice sized potatoes from the slips I took off of just a single sweet potato. Sweet potatoes love our extended summers so let them grow about 4 months. I usually plant in May and harvest in September. But keep in mind you can plant them as late as July and still get a decent crop. And don’t forget that you can eat the leaves. Another added bonus is that once you grow sweet potatoes, they will often come back on their own the next year from immature roots that were left in the ground during harvest.
Near the end of their growing life sweet potato vines will start to yellow. This is a good sign. They’re ready to harvest when the leaves start to yellow and the cooler weather of fall is in the air. Don’t water the sweet potatoes for one week prior to digging them up. This allows them to dry out and come out of the ground cleaner.
If we have an unexpected early freeze you will want to act quickly to dig them up right away as once the vines get touched by frost and start to turn black the sweet potatoes can rot quickly.
Cut the tangle of vines away, leaving only a few stubs to let you know where the plants are.
Using a shovel or digging fork, dig em up. Honestly, the most fun crops to grow are the ones that grow underground because you have no idea what you will get until the day you dig them up.
Be careful when you’re digging them and pulling them out. Sweet potatoes bruise easily.
Harvesting sweet potatoes doesn’t end with digging them up. Once you dig them up you must let them dry in the sun for a few hours. Then they need to be taken inside and cured for 10 days and then cured some more for another month or so.
I know that sounds like a lot of trouble, but it is worth it. Curing toughens the skin, so they keep longer and it develops their distinctive sweet flavor. A sweet potato dug straight out of the ground won’t taste nearly sweet and might not be at all. Try it.
The optimal conditions for curing sweet potatoes are in an 85-degree room at 85 percent humidity. But don’t worry. All you need to do is get as close to the ideal conditions as possible. You can do this relatively easily by placing them in a plastic bin with the lid offset so it isn’t completely sealed off. Store this in a warm area or sunny spot. This will create conditions as close to perfect as you can get in most houses. Do this for 10 days.
After the initial 10 day curing period, move your sweet potatoes to an area that is between 55-60 degrees for one month. This helps develop and deepen their flavor. After 1 month they will have reached their best sweet potato flavor, but the flavor will get even stronger as time goes by.
One bit of caution here, the decorative Sweet Potato Vine you buy in the bedding plant section of the nursery isn’t the same thing. You can not eat it — but it can be propagated the same way I described here.
Joe Urbach is the publisher of GardeningAustin. com and the Phytonutrient Blog. He has lived in the Central Texas area for over 30 years.