Sweetpotatoes (Ipomoea batatas)
Sweetpotato Varieties I Used To Grow
USDA National Germplasm Repository (Griffin GA) Selections I Used To Grow
Sweetpotatoes (often mistakenly called yams) come in many more varieties than the typical orange-flesh type. Yams as commonly sold in the US are really mis-labeled sweetpotatoes. The name of "yam" was given to moist, orange-fleshed sweetpotatoes, even though the true yam is neither moist (it is dry-fleshed) nor orange (I believe they are more of a reddish color inside). True yams are rough and scaly, but items labeled yams are usually smooth and thin skinned, identifying them as really sweetpotatoes. And sweetpotatoes are not related to Irish potatoes either.
To make things even more confusing, sweetpotatoes are not always orange inside. They can be white or purple. Purple sweetpotatoes? Yes, really. Outside and inside. And even more colors. All edible, with different tastes and textures.
I grow some of the more exotic colored sweetpotatoes. And not just for the looks. The purple ones have desirable nutrients similar to other purple foods, like blueberries, grapes, and purple cabbage. Purple-colored foods are attracting attention because of the beneficial effects on health the natural purple pigments have. Sweetpotato varieties I grow are in the menu box to the right.
Sweetpotatoes require a long growing season, about 120 days to harvest. They should be planted into the ground after the soil has warmed to about 60F-65F. I plant my sweetpotatoes in mid May to the end of May here in Missouri. That is a month after the time of our last frost date (April 15 here).
Note: Sweetpotatoes should be started from "slips", the sprouts that come from stored roots. An entire garden can be planted from the slips taken from just a few roots. The slips are broken off of the root and put into potting soil and watered so that they form their own roots. I use small individual root pots (this keeps the roots from other slips from getting tangled). I gradually accumulate rooted slips until mid May, when I have quite a few ready to put out into the garden. Okinawan and Kotobuki are a little more difficult to sprout than most sweetpotatoes.
Sweet potatoes must have well drained soil because the roots must have oxygen. They will not tolerate being water logged. I have clay soil, so I push up a ridge in my garden and plant them on the ridge. Works just right.
Sweetpotatoes do well on poor soil, in fact they will not do well at all on rich soil. Too much nitrogen and they put all their growth into vine and not roots. They need moderate nitrogen but lots of potassium and phosphorus. Here's a good reference:
University of Georgia Extension: Sweet Potato Production
Note: I don't grow Okinawans any more. They did not do well for me, probably because I don't have the fertilization method figured out quite yet and also because they were very hard for me to start sprouting from the roots. I now only grow the Purple, Vardaman, and Kotobuki. These have been good producers over the years and sprout easily. Also, it is very hard to find a place to order Okinawan slips from. I don't know of any commercial source. You can get them from individuals who grow them. Sand Hill still offers them. See their link to the right.
Sat Apr 17 2010 at 9:40:59am