Can These Sweet Potatoes Be Saved?

I’ve been harvesting sweet potatoes since early October. A lot of them are damaged by animals, the most damage I’ve seen in 4 years of growing sweet potatoes. I suspect rodents, possibly mice or voles because the side facing the soil surface is damaged. C

At the Vassar Farm community gardens about 1/4 of my sweet potatoes were damaged. I brought most of mine home and cooked the smaller damaged ones immediately. My neighbor’s sweet potatoes were also damaged and I salvaged a couple of their huge cast-offs from the cull pile.

10/19/2010 Two from the cull pile: the left SP weighs 1.75 pounds even though half was trimmed away, the right SP is a bit over 1 pound.

All together, I have around 15 pounds of very damaged sweet potatoes. That is too much to eat right away so I would like to cure them for storage. The curing process sweetens the potatoes and intensifies their flavor. Is is possible to cure these damaged sweet potatoes, and how long will they last in storage?
As you can see from the pictures, I’ve handled the damaged sweet potatoes two different ways. I washed all of them, scrubbing lightly with a brush to remove soil. For about half the sweet potatoes I cut away the damaged area. The rest I left in their original gnawed condition. The gnawed areas were already dried at harvest time so clearly the animals had been dining over a period of weeks.

10/19/2010 Damaged Sweet Potatoes 'Georgia Jets' from my garden. Most of the SPs are curing without problems.

Most of the damaged sweet potatoes were heaped in a large bowl covered by a dish towel and placed on top of the refrigerator to cure.
All photos are  Ipomoea batatus ‘Georgia Jets’ .

Storage Results:

Oct 18: My fist check, after one and a half weeks of storage showed some problems: a couple sweet potatoes had developed wet rot. I discarded those sweet potatoes and washed the mold from the adjacent potatoes. Another huge SP in an uncovered bowl also developed wet rot. I cut off the rot and I’m trying to cure the sweet potato, but watching closely.

I’m now checking the sweet potatoes a couple of times a week, just to make sure there are no more problems. I probably could have caught the wet rot problem earlier: a couple sweet potatoes had spots that looked wet and didn’t dry, and which could not be dried with a paper towel. Now I know: cut out the ‘wet’ spot and use the rest immediately.

Oct 28: There have been no additional problems. I’ll continue to update this posting as I cook the damaged sweet potatoes.

Oct. 29. This is the huge sweet potato that I discovered had wet rot on 10/18. It looks like I was successful in removing the rot then storing the SP. I discarded about 25% of the sweet potato when I prepared it for cooking. The remaining 1.5 pounds made a fine casserole. The whitish area on the surface is a well dried crust.

10/29 After I cut away some rot on 10/18, this sweet potato cured successfully.

Nov. 8: This one surprised me. When I cut into it, I discovered some dry rot – at about 12 o’clock in the picture. Again, I discarded about a quarter of the sweet potato before cooking it.  There were a lot of cracks and fissures on the back of the SP which don’t show in the picture.

11/8

Nov. 10.  Some of these smaller SPs are not storing as well as the monsters. The two on the left look like a complete loss. These are the same SPs photographed in the bowl on 10/19.

11/10: some cure better than others, and there is no telling in advance which will store successfully if they are damaged.

Sweet Potatoes: Growing, Harvest, and Curing

Imagine harvesting sweet potatoes in Dutchess County, N.Y. Many Farm & Home Center visitors were surprised to see a cluster of dark red sweet potatoes “hanging” in the soil on Open Gardens Day 8/29/2008. I had pushed aside the luxuriant vines and dug a hole at the side of the sweet potato bed.  A few minutes of work exposed the potatoes, which grow straight down.

Georgia Jets Sweet Potatoes awaiting harvest

The sweet potato plant, Ipomoea batatus is native to tropical regions of South America. It thrives in long hot summers but a few varieties can be grown in the north because they mature in only 90-100 days. The variety I grow, Georgia Jets, produces a heavy yield of sweet, red skinned, orange fleshed potatoes.

Sweet potatoes are grown from “slips”: sprouts removed from the sweet potato and rooted. We ordered our slips through a seed catalog. Vendors ship the slips at the correct time of planting in your zip code, so orders for Dutchess County ship in late May for planting in warm soil after all danger of frost is past. Unfortunately the order often languishes in the Post Office over the Memorial Day Weekend – a bad situation for the slips.

After planting, sweet potato slips eventually grow into 4-6′ long vines with flowers that show their relation to morning glories. They can root and produce potatoes along the vine. I’ve found nicely sized tubers up to 2′ away from the original planting.

Sweet potatoes vines will not survive a frost (or deer). Japanese beetles also nibble the foliage. The most common problem with sweet potato tubers is splitting when they get very large, or from uneven moisture. The split potatoes usually heal, and can be stored after curing, although they should be eaten first.

The sweet potato tubers must be dug immediately after frost, but they can be dug any time after they have sized up – as early as late August. The Perdue University Cooperative Extension Service says that “Sweet potatoes should be cured before storing to heal wounds and improve flavor. It is during the curing process that starch is converted to sugar.” Curing is definitely needed for the best flavor: I cooked and served a freshly dug sweet potato this week and the flavor was flat and lacking natural sweetness.

“Cure sweet potatoes by holding them for about 10 days at 80-85°F and high relative humidity (85-90%).” These conditions are very difficult to find in D.C., N.Y. in October, but Perdue says that you can compensate. “If the curing area’s temperature is between 65-75°F, the curing period should last 2-3 weeks.” Just be sure to maintain the required humidity. In the past I’ve cured my potatoes by piling them all together in a big bowl and leaving them on a kitchen counter for a few weeks. Then I laid them on a shelf in my unheated basement, which provides the perfect storage temperature. That worked quite well: the potatoes were still good in March!

This article was first published in the Oct. 2008 issue of Dutchess Dirt. Since then I’ve learned a few more things about curing sweet potatoes.

I tried curing my sweet potatoes in a plastic storage box with the lid in place. That kept the humidity too high; so high that moisture condensed on the lid. Many of the sweet potatoes  started sprouting. Luckily I discovered the sprouts while they were still tiny, and moved the sweet potatoes to my basement storage area immediately. The sprouts stopped growing and stayed the same size all winter. When I started my slips the next spring, I chose potatoes with sprouts to root. With roots and warmth the sprouts resumed growing and produced slips quickly.

This year I used a loose dish towel to cover my bowls and plastic bins of curing sweet potatoes. That seems to be working quite well. The humidity is higher than ambient, but not so high it condenses of the sides of the containers.

Close-up:Georgia Jets Sweet Potatoes showing how the potatoes form under the soil surface.