Monday, April 30, 2012

Starting Sweet Potatoes


Supplies to Start growing Sweet Potatoes Indoors
Unless you are dealing with the Okinawan purple sweet potato, most sweet potatoes are pretty easy to start. One very good step to starting sweet potatoes is to find a potato variety that grows in your area. Georgia Jet seems to be one of the most popular varieties as it can be grown throughout most of the United States.

I prefer to find a Farmer’s market or a local farmer who is able to provide me with potatoes from my climate. I find sweet potatoes do very well here in the southwest, though regular potatoes do not.

I purchased my “seed sweet potato” from a local Whole Foods market in a section where they stated that it was grown locally and they produced a good number of potatoes. I am assuming the variety is Georgia Jet, though I can’t be certain. Previous to growing out the local variety I grew out two varieties I had bought from the grocery store that were from another state. The out-of-state potaoto grew large but produced very few potatoes.

Sweet Potato Halves now in water for Growing

 To start sweet potatoes, you will need a location to keep the seed potatoes very warm (80-90 degrees F). I use a reptile heat mat with a rhetrostat to keep the temperature consistent. You can choose to sprout them suspended in a jar with toothpicks or you can choose to start them in some kind of pit filled with sand or some other substrate. The important thing is lots of moisture and warmth. I prefer to start mine inside to grow out small sweet potato plants or “slips” from the potato.

Beginning Root Formation on Sweet Potato

Why not just plant the whole potato in the ground? There is always a chance that the potatoes might rot underground, causing disease in the soil and which can be spread to your new sweet potato crop. In the sweet potato industry they will grow out new plants out of the potato in growing beds and harvest the young plants (called slips) from the soil when they grow large enough to continue growing without the mother tuber. These slips are then transported to the fields where they are transplanted and grow into the sweet potato crop. There is another method (that I outline in another post) to starting sweet potatoes in the garden that allows them to get started quickly as long as you are using known healthy sweet potato stock.

Sweet Potato Slip (plant) forming on mother potato.

Growing out Sweet Potato Slips: For my jar and toothpick method I cut the sweet potato in half and suspend 1/2 to 2/3 of the potato below the rim of the jar using toothpicks. Then I fill up the jar with water, put it in a warm place and make sure to change the water often. It can take 1-2 months to get sweet potato slips started so make sure to plan that much time in advance.

Full Grown Slip on Sweet Potato

Care: Compared to many other vegetable varieties sweet potatoes are relatively maintenance-free and do not require an excessive amount of fertilizer or pest control to grow strong healthy plants. They do perform better in areas where the dirt has at least had the large rocks sifted out. Once they have established themselves I just keep them well watered and occasionally make sure no large creature is chewing on the vines. Some bugs will chew at the vines but usually the vines grow faster than the bugs can reproduce.


Sweet Potato Slip



The Sweet Potato Slip now a Sweet Potato Plant in my Garden

Harvest: I usually harvest right after the first slight frost. Sweet potatoes tend to die at the slightest frost, which around here can often be in November or December. Though some use pitch forks to harvest their sweet potatoes, I choose to harvest by hand, following the roots from one tuber to another. Once I harvest my sweet potatoes I keep them moist and warm in my water heater closet to cure them. Curing the sweet potatoes allows them to store longer, which is essential I would like to plant sweet potato vines out again next summer.

An All Purple Sweet Potato - Slips available through SESE

22 comments:

  1. Love sweet potatoes but I am more of a yellow sweet potato lover than a yam lover...I usually buy my slips but if I can find some nice organic sweet potatoes I will try this method...we have such a short season, we barely get a harvest, but I keep trying...I grow them in grow bags.

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  2. Dear Donna,
    Thank you for your post.

    When you say "yam" I am a little confused. I know that "yam" here in the United States was used as a marketing tool to differentiate one kind of sweet potato from another, whereas actual yams can are only grown in the tropics and can weigh over 100 pounds. I am thinking that you are referring to yam as some kind of orange fleshed sweet potato. Some grocers are starting to catch on and are labeling the sweet potatoes by their actual variety name such as “Garnet” or “Beauregard”.

    I was able to produce a larger crop of sweet potatoes by finding a variety that was grown locally - from a farmer's market or a local farmer. My experience with growing organic sweet potatoes grown in another area of the country was that they did not produce much. For me it had more to do with the variety than with how they were grown before I received them. Now that I have grown them myself I can say that my variety is now 100% organically grown. (=

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  3. What an interesting post - I will give your method a try next year. I have just checked on the RHS website and 'Georgia Jet' is reliable throughout the UK too.

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    1. Dear Gardening Shoe,
      Thank you so much for your reply.

      That is great you found some sweet potatoes you can grow in the UK! Unfortunately there are not a lot of sweet potato varieties that do well in the far north, though I am glad you found one that is available for your area.

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  4. They look very good. This is interesting. Thanks for sharing this post.

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  5. Excellent step-by-step instructions. Looks fantastic!

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  6. I am glad you enjoyed it. (=

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  7. Hi i first saw you name today as the topnotch picker! I love your way of starting your sweet potato, but here where that is very common, we don't need to produce the slip as we get vines from the old plants and directly plant the cuttings, lots of two foot stems per mound with 2 ends protruding at both ends. Our climate is more difficult than Az clime.

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    1. Hi there Andrea.
      Thank you for your response. Where do you live? I have read that if you leave the potatoes in the ground without transplanting the slips that the old potatoes can cause disease. So, are you saying that you start your potatoes in one bed then transplant them into another bed?

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  8. Very good instructions. I am wondering about Colorado potato beetle, do they like sweet potatoes because they have foiled my previous potato growing efforts.

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    1. Dear Carolyn,
      Thank you for your response and question.
      I do not believe Colorado potato beetles would eat sweet potato leaves. Colorado potato beetles prefer members of the nightshade family including potatoes, tomatoes, peppers and eggplant. Sweet potatoes are in a different family of plants - called convolvulaceae. This family of plants includes morning glory and bindweed.

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  9. Great presentation! I am reminded of my husband when we first met. He had a 'pet' sweet potato which he had put in a jar with water. It was growing rampantly across his window sill and down his wall. It never occurred to him to plant it!

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  10. Okay, great. What if I am dealing with beni imo (the Okinawan purple sweet potato)? Does it just have to be that much warmer to start them?

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    1. Thanks for the question, Jarrett. Well - I'm not really sure. I had very little luck with starting that variety. I tried both heat and lack of heat. They just wouldn't grow much.

      I believe they do best in other climates - perhaps they require shorter days without any freezing temperatures to really do well. They are grown in Hawaii and other tropical areas.

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  11. Thanks for the post, Jay. What is optimum time for planting slips into the ground in the Tucson area?

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    1. Dear Darce,
      Thank you so much for the question. I usually wait until the soil is nice and warm. Mid March is almost too early. Beginning to mid April is preferable. When we reach the low 90s is probably a good indicator that it is time to plant slips. As I stated before, you will most likely have a good experience with locally grown sweet potatoes. Myself and others have found that many store-bought varieties will not produce much underground. If you can't find a farmer's market with good locally grown sweet potatoes I have both an orange and purple variety that I am willing to sell (if you are in Tucson).

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  12. Hi, could you tell me if you just used one half of the potato or if you placed each half in it's own jar? I would like to grow these too. Thank you.

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    1. Dear Patty,

      My experience has been that Sweet Potatoes grow better in Jars when cut in half, with the cut side facing down. Best wishes with your gardening!

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  13. Great gardening blog! We bought two small Okinawan purple potatoes last year at the health food store. One went "south" soon and the other started sprouting so we put in a jar of water and as mid spring rolled around it had a cluster of sprouts, each no longer than three inches. Can't recall if we rooted them as we did the orange sweet potatoes, they were from Mississippi as we bought a box of them at the local grocery. Well, imagine our surprise as we just harvested about forty pounds of purple sweet potatoes and twice as many orange ones. Some of the plantings were just pieces of sweet potatoes that had "eyes". In digging them up the spouse was surprised the bigger purple potatoes were over a foot down in the soil. We are adding new recipes via internet as there is a limit on butter and maple syrup.

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  14. Sweet potatoes do not have tubers which are modified stems. They have modified roots which are typically called storage roots.

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    1. Why hello!

      I learn something new each day. Thank you for telling me this. Sweet potatoes are quite a bit different from regular potatoes, aren't they?

      Happy Gardening!

      -Jay

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