Tuesday, May 28, 2013

Starting Sweet Potatoes in the Garden


A few years ago when I began working with sweet potatoes, I preferred to grow out the slips from sweet potatoes cut halfway in a jar. However, as I have experimented with different techniques I have found that starting sweet potatoes in sand or soil is much faster, howbeit a bit more complicated.


Putting Sweet potatoes out for transplants
 

Placing the sweet potatoes in the Garden
 
 
Purple Sweet Potatoes for Slips
 
So – what makes starting sweet potato slips in the garden tricky? Disease, nematodes, and various other factors have led to farmers to grow out small plants (or slips) from sweet potatoes rather than planting the tubers themselves. Transplanting sweet potato slips can be a rather simple process in a very moderate climate (where sweet potatoes do not grow well). In contrast, in hot southern climates (where sweet potatoes grow very well) transplanting can be much more difficult. This is because by the time the slips are ready to plant in May the 100Fahrenheit (38Celsius) daytime heat cooks the roots of the sweet potatoes down through the first 6 inches of soil. This means that either the roots must be very long or the plants must be given additional care until they establish themselves.
 
 
All Purple Sweet Potato Slips

My experience this last month with growing and transplanting sweet potato vines has taught me that transplanting slips requires timing, hardening off, and recovery time. By timing I mean that I have found that it helps to transplant the slips in the evening. By doing this, it gives the roots a little more time to enjoy cool soil before the sun and heat begin to stress the plant. In very hot climates sweet potato slips need to be hardened off before they are exposed to the full sun. Until the plants stop wilting, temporary shading really helps to give the roots time to grow and helps to “harden off” the plant. Even with planting at night and shading, it may still take several weeks until sweet potato slips are ready for the intense heat of the Arizona sun.
 

Sweet Potato Slips recovering
 

More recovering Sweet Potato Slips
 
One other nonconventional means of transplanting sweet potatoes is the growing of sweet potato slips from tubers in the garden, then removing the tubers from the garden. This is the opposite idea of transplanting slips. With this method I mark (with a stick or some other marker) where I want to plant a very healthy disease-free sweet potato. Then, I put the sweet potato in the ground and cover it with garden soil. I then water it, just as she would any other plant in the garden. Next, I wait until the sweet potato grows out and the plant becomes established. Once the plant is about 18” long, then you carefully poke around for the potato and (with a fingernail or another sharp object) I remove any vines from the potato. Then I pull out the original sweet potato and fill in the hole with soil. With this method, you have to be very careful to keep from disturbing the roots of the growing slips. By doing this, you can keep from losing the 2-3 weeks of shock and recovery required when transplanting the sweet potato slips.

Several weeks later - the vines have recovered
 
This “starting slips in the garden” method is fraught with all kinds of potential disease issues. However, if you have never had disease problems with sweet potatoes and are using very healthy disease-free tubers, then you might be willing to take the chance of keeping sweet potatoes in your soil just long enough to allow the slips to establish themselves.

Sweet Potatoes Started in the Garden - with tubers removed


 

3 comments:

  1. Fascinating Jay. I usually planted slips and by the time the first frost came I had a few good size potatoes. Our growing season is just not long enough I think. So I gave up the space to blue potatoes my favorite.

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  2. i would like to offer a alternative that i call the power plant method. in canada we need to speed things up so this is how it works sprout a healthy sweet potato a bowl of water (important-don't puncture the skin) once there are a few very long slips it can be put out in the garden and covered with something to keep the sun off and the slips still attached are buried at a appropriate node. wait 5 weeks until plants have thoroughly rooted then cut the slips(now large plants) from the potato in the bowl. this gives the slips a unlimited amount of resources when establishing there own roots by cutting the vines you ensure that when they enter the bulking phase none of the starches get stored in the original root. this can cut maturation by at least 3 weeks

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    Replies
    1. Dear Billy,

      Thank you so much for your response! I am glad that you found a method that works so well for you.

      Obviously, you have a different climate than what we would experience in Southern Arizona. In warmer Arizona climates large milk jug containers filled with water and put around the planted sweet potato provide plenty of heat to get the plants started outside.

      There is another post where I describe the method of starting slips from cups, but like you say it can take 5 weeks or so, whereas those who live in warmer climates can really see the benefits of starting sweet potatoes in the ground in about 2 weeks, as long as the daytime temperature has risen to at least 75 degrees Fahrenheit.

      Just as you mentioned, any method used should include removing the "mother" potato from the slip as soon as the new plant is able to support itself.

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