It is late May, and that means it is time for me to plant sweet potatoes. Sweet potatoes are actually fairly easy to grow, but they do have some specific requirements that need to be met in order to be successful. First, they like the heat. Or I should say, they demand the heat. That’s one reason I wait until now to plant them. Here in late May, the soil has warmed up nicely (it has been 70°F or more the last few days), and daytime temperatures are warm as well.
The second thing sweet potatoes like is a loose, well-drained, slightly acidic and not too fertile soil. I like to make a ridge of soil that is 8 to 10 inches high and about as wide before planting. It takes a little effort to make the ridge, but that will be the last real bit of work they require for awhile after planting. The ridge of loose soil ensures that the potatoes will have no restriction to growing nice, big roots. And it also will keep the root zone warm and well-drained, just like the sweet potatoes prefer. Northern growers sometimes cover the soil with black plastic to help it warm up, but here in Southern Indiana that is really not necessary. I will come back in a week or two and mulch with newspaper covered in straw to keep down the weeds. The soil will still get plenty warm even with that treatment. The mulch will also keep the soil moisture from fluctuating too much, which can result in the roots cracking.
Once the ridge is made, I lay the sweet potato slips about 14 to 18 inches apart along the row, then I plant them. The slips will root all along the stem, so I usually plant about 4 inches deep. If you order sweet potatoes, they will often arrive in the mail looking sort of sad, but never fear. The slips are tough, and should do just fine. I grew my own slips for Carla’s Purple and potted them up for a couple of weeks before planting, so they had a nice root system on them. And I bought Beauregard slips from my favorite local garden center, Robin’s Nest (in Boonville, IN). They too were potted up in groups and nicely rooted.
After planting, I give them a drink with a little fish emulsion solution. And that will be the only fertilizer they get. I don’t amend the soil right before planting, and I don’t add any other fertilizer throughout the growing season. My soil has tested with ample amounts of phosphorus and potassium for the sweet potatoes, and too much nitrogen can result in lush foliage but small, spindly roots. If that is a problem in your garden, it is possible that your soil is too rich and fertile to start with. In that case, I would find another location or else try growing them in containers. I got that little bit of wisdom from James Crockett, and from local sweet potato growing ‘experts.
I’ve never had any problems with growing them here. Heavy clay soils may need to be amended with organic material to loosen them up, but that is not a problem either given our silty loam soil. I will give them additional water if they need it. They really need about an inch of water per week for optimum results, though too much water in the final stages can also cause the roots to crack. The water is most critical in the first month of growing.
And that is how I plant my sweet potatoes! It was a great way to start my morning yesterday, and I got in a little exercise moving the soil to make that ridge. Once I come back and mulch with the paper and straw, I won’t do anything except keep them watered until about 4 months from now, when it should be time to start digging them up.
In my garden, the vines are rarely bothered with pests, but since the vines are edible they are a favorite food for rabbits, deer and groundhogs. Last year a rabbit camped out inside my garden, and kept the vines mowed back all summer, which definitely cut back on yields. This year they should be safe and secure inside the new garden fencing. I do rotate my crops so that the sweet potatoes aren’t grown in the same spot for at least another 4 years. That will help lessen the chances of diseases or insect problems.
Sweet potatoes are one of my favorite foods, and a staple storage vegetable here for us as well. We had some of the 2012 crop for dinner last night, fixed on the grill. I hope you have enjoyed reading about how I grow them, and if you’ve never tried growing them yourself you might give them a try!
For more information about growing sweet potatoes try these sources: