From the Inbox: Problems with Sweet Potatoes - Help!
Anyone have any advice for Lyda?
"I started growing sweet potatoes a few years ago. My first experiment was a rather successful one. I purchased an oriental sweet potato from an Organic Farmers Market and just put it in the ground and watered it. Once it started to sprout I clipped off some cuttings ( I didn't understand what slips were at that point), took off most of the leaves and dug those cuttings into the soil in a corner of my yard covered in mulch. 5-6 months later I had a 5 gallong bucket full of Sweet potatoes. I thought I was in heaven and couldn't believe everyone wasn't growing sweet potatoes. Since that time I have been plagued with bad crops. After that first crop I dug some home compost into that corner of the yard and started again. The vines grew like crazy but eventually became infested with white flies. When it came time to harvest there really wasn't much in the ground. Just tiny little or long skinny ones on the root. Last Spring I used some of those same small sweet potatoes to start slips from a jar. The slips grew great. The first ones were put into a grow bag in March, which in South Florida is pretty warm as you know. I also have some planted in raised beds and they are now completely infested with white flies. It was from that first bag that I harvested today.
I have a few theories/ideas:
1. I have been told to start with Certified Seed Potatoes to get a good crop and mine were not. That same person said that you may get a good first crop but then successive generations from those potatoes will be small. This describes what happened to me. The first crop was good but then when I continued to use the potatoes grown from that original the crops were smaller and less bountiful. Maybe I should have ordered slips or purchased a new potato from the market to grow slips?
2. Starting from small potatoes....would that have anything to do with it. I just figured it didn't matter as long as I had a slip or cutting to start with.
3. I thought my 2nd crop was so small because I had mixed in compost that had Chicken Manure in it and the nitrogen caused me to get alot of vine growth but little potato growth. This would not be true of this year's crop because I got rid of the chickens 18 months ago and there is no longer any chicken manure in the compost that was added to the grow bags.
4. Does pruning the vines cause less potato growth. I have been trimming them back when they grow into walk ways etc. and adding the cuttings to the compost bin. I did not do that for the 2nd crop though and had the same result.
Any thoughts or knowledge would be appreciated. Feeling frustrated after waiting 6 months and thinking there were potatoes growing in there."
On #1, I've never worried about "certified seed" on sweet potatoes. I believe that's usually a white potato issue. My guess is that soil nutrition has decreased.
#2: It's never mattered for me. They're regularly started from slips without issue.
#3: Nitrogen could perhaps lower root production, but I'm not sure why that would be a continuing issue this far in. Hard to know without an idea of how much nitrogen is still available. You could always plant a crop of corn to soak up some of what's left, if there is too much left.
#4: Yes. Cutting back growth lowers the photosynthesizing power of the plant. Less area for light gathering; less stored in the roots.
Whiteflies have never been an issue for me in N. FL, but they're definitely an issue down south.
Anyone else have ideas for Lyda?