Sweet Potatoes Didn’t Do That Well This Year

Last year I planted a few sweet potato slips for funsies. Some store bought sweet potatoes had sprouted and I decided to root and grow the sprouts. The result was impressive, to me. I found that each slip grew 3 large (about a pound each) potatoes. They were good and actually tasted better than the store bought ones.  This picture shows a small part of the harvest.  These potatoes are nice, rounded and large.  The meat was rich orange.

2016, first year of sweet potatoes

With a big, easy harvest in mind, this year I planned to plant several dozen slips. I struggled to get a new batch of store sweet potatoes to sprout in time to plant in May. I was expecting to harvest maybe upwards of 50 pounds of potatoes.  Sweet potatoes are supposed to be easy to grow.  Plant them and let them grow all over the place.

Hah. Didn’t work out.

After waiting 5 months or so for the fall frost and harvest time, I was totally disappointed. At the base of each slip that grew into a long, nice looking vine I expected to find three large sweet potatoes.  What I found was . . . nothing.  Almost nothing.  Most of the slips looked like this – no potatoes formed at base of the slip.

surprise - no potatoes at slip base

Some of the slips had very small potatoes.  These potatoes are finger sized, not one pound beauties.  The orange arrows show roots, just roots.  Last year, just a few inches under the soil, attached to the main stem, each slip grew 3 large potatoes.  Not this year.

small sweet potatoes at base of slip

This is most of my sad, sorry harvest.  Most of the potatoes were small, no more than 4 onces each.  The very few potatoes that were reaching towards half a pound are all bug damaged.  You can see the round holes on this bigger potato.  Some are redish, some are orangeish,all are small.

sad sweet potato harvest 2017

The vines looked very good in early summer.  There are winter squash vines in the lower front of the pic.  All of the other vines on this cattle panel are sweet potatoes.  Due to space limitations, I grew them up cattle panels.
Sweet potato vines lookin' good in early summer

My vines did not show any signs of either over or under fertilization.  If they were under fertilized, I would have be seeing the leaves yellowing and progressing to brown and then death.  If they were over fertilized, I would have expected to see an even more, lush canopy and possibly rolled up leaves.  I did not see any of this.  While my vines were acceptable, they certainly were not overly lush or ill looking.  So, I have to rule out the probability of fertilization issues.  The winter squash and peppers looked fine.

Sweet potatoes should take from 100 to 140 days from the planting of the slips.  I planted my slips in late May and early June because of the trouble in getting the slips to grow.  I harvested them around first frost, in October.  Some of them could have been growing for up to 150 to 180 days.  I had considered the possibility that I left them grow in the ground too long and that the larger potatoes had rotted, but other than a few rotted larger potatoes, I did not really find any evidence that there were lots of rotted potatoes.  But I can’t be absolutely sure the older, larger potatoes hadn’t rotted away a month earlier,  but I doubt it.

Excessive application of nitrogen can result in low or no yields, but I only sprinkles a few handfuls of organic fertilizer around them when the vines were small.  I by no means over fertilize anything in my garden.

Assuming the soil is sufficiently fertile, the slips only need to be fertilized once.  One side dressing of 10-10-10 when the slips are 8 to 12 inches tall is supposed to be sufficient.  Sweet potatoes do not need much fertilizer if the soil is fertile.

So I have ruled out over or under fertilization issues.  I have almost totally ruled out the possibility that an original crop of potatoes had rotted and that I only got small re-growth.  The plants got sufficient, but I don’t believe excessive, moisture.  They are growing in raised beds so the soil does not sit sopping wet.

Most of my “larger” sweet potatoes had some kind of bug damage.

bug damage on sweet potatoes

This one, one of my biggest, was really damaged.  Looks like some kind of worm holes that caused the rot.
sweet potatoes rotting

One of the few slips that had some form of sweet potato growing on it.  Notice the stem, where my thumb is, has lots of tiny pin holes in it.  Many of the stems had these pin holes, but the leaves still looked fine so they were getting enough nutrients and water thru the stem.  Maybe the leaves couldn’t send any nutrients back down to store in the roots????
sweet potato at slip base

I’m very disappointed, but will try again this year.  I am going to try to sprout some more store bought potatoes.  I am going to look for organic ones because they supposedly won’t be sprayed with a sprout inhibitor.  Also, don’t try to sprout sweet potatoes that have been wrapped in plastic.  The potato needs to be living and if it has been sealed in plastic for very long, the potato may have been killed.

Another spring, another time to try again.

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