By Jill Henderson - Show Me Oz
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Last week we learned quite a bit about the history and uses of the deliciously edible and nutritiously dense sweet potato. With a surge in popularity among homesteaders and gourmet chefs alike, this homely root with the pumpkin-colored flesh is being grown in home gardens in quantities not seen for decades. And it’s no wonder; for sweet potatoes cover a lot of ground. They’re easy to grow, relatively care-free and beautiful to look at. The roots pack a nutritional punch, taste great, are low in fat, and will fill you up every time. Sweet potatoes are a dream to cook with partly because of their uncanny ability to be prepared in so many ways. They can be baked, boiled, steamed, mashed or fried and added to a myriad of dishes with flavors ranging from sweet to savory. No matter how you prepare this wonderful root, it always tastes good. In this week’s article I’ll cover everything you need to know so you can grow your own sweet potatoes from start to finish!
Sweet potatoes need a long growing season to produce a good crop – most take between 90-150 days depending on the variety. Sweet potatoes also do not tolerate cold soils or frost. They prefer full sun, but a bit of light afternoon shade helps retain moisture in the leaves and soil. Many a fact sheet on sweet potatoes will tell you that sweet potatoes need loose, well-drained soil, but I’ve been growing sweet potatoes in heavy Ozarks soil for 12 years and have yet to be disappointed in their yield or form. As long as the soil drains well, you can grow a nice crop of sweet potatoes. If your soil doesn’t drain well or is overly rocky, work in plenty compost, leaf mold, shredded leaves or straw in the spring and keep the bed well-mulched.
For the farmer or home gardener, sweet potatoes are always propagated vegetatively through vine cuttings or root sprouts known as “slips”. The true seeds of sweet potatoes are viable, but will not produce a reliable crop. True seeds are used primarily for breeding purposes. Good quality, disease-free slips are available at many nurseries, but you can easily start your own sweet slips at home.
To sprout a sweet potato, begin with slender, unblemished, organically-grown roots. Do not use the most gigantic rootyou can find, instead look for those that are 1-2” in diameter and 6-10” long. These young roots produce more sprouts in less space. Also, do not use sweet potatoes from the grocery store for sprouting unless the potatoes are marked organic. Almost all commercially produced sweet potatoes are treated with an anti-sprouting chemical that cannot be washed or worn off. You might be able to coax a few slips from one of these, but usually they rot from the inside out before generating sprouts.
Avoid using sweet potatoes that have nicks, cuts, scars, bruises, sunken spots or any other kind of malformation, as these can be indicators (and incubators) of disease, which is why you should never plant sweet potatoes as you would Irish potatoes. Slips are much less likely to carry and transmit these kinds of diseases.
There are two methods of sprouting sweet potatoes – in water or in a hot bed. For most gardeners, sprouting in water is the most common method. Plan to start the process about 6 weeks before the last frost in your area.
Find a large jar or other container into which you can easily fit the bottom third of the sweet potato and fill it with water. You can use any kind of vessel, but canning jars work very well. Push two or three toothpicks into the sides of the sweet potato so that about 1/3 of the root is in the water. Place this in a warm sunny window. The warmer the spot, the faster the sweet potato will grow. If conditions are right, the sweet potato should begin sending our roots in 7-10 days and sprouts should begin to appear within three to four weeks. Allow the sprouts to grow as long as possible.
I searched high and low for reliable information on which end of the sweet potato grows foliage and which end grows roots. The conclusion: Sweet potatoes will sprout from whichever end – or side – is up.
bout 10-14 days before the recommended planting date in your area (refer to your local extension office) begin rooting the new slips. Some sources recommend gently twisting the vines off of the root in such a way as to take a little piece of root with the cutting. There are benefits to this method, but it reduces the overall number of slips you will get from each potato and doesn’t affect how well the vines produce. It does, however, carry a bit of the root, which could also carry disease.
When rooting cuttings, keep in mind that every piece of a sweet potato vine that contains at least one leaf will grow roots and will do so very quickly. All one need do is cut the vine into manageable lengths – 4-6” is the recommended size, but even a tiny little stem will set roots. Place the cut ends in a jar of water and keep them there until they form roots.
The method used by large scale producers is a two step process. First the roots pre-sprouted at 75-80° F. and 90% humidity for up to a month. As soon as the buds break, the roots are moved to sand-filled hotbeds where they are planted on their sides 2″ deep and 1″ apart. The are kept at a constant 75-80° F for an additional 6 weeks. This method, while not always feasable for the home gardener, is said to produce excellent quality slips.
Once all the slips have rooted and outdoor soil temperatures have reached 60-65° (usually about two to three weeks after the last frost date), plant the slips in the garden 2-3” deep and 12-18” apart. Keep well-watered until established.
A few tips for growing sweet potatoes: Plant in well-drained soil with a pH of 6.0. Use a three year crop rotation to avoid diseases and soil pests such as wireworms and flea beetle larva. Finally, never plant sweet potatoes following a cover-crop of legume, they excess nitrogen will enhance leaf and vine growth at the expense of root formation.
Sweet potatoes are a wonderfully delicious and nutritious crop that is easy to grow, drought resistant and beautiful all at the same time. The best part – there’s still plenty of time to start your own sweet slips for this year’s garden!
What’s the difference between a sweet potato and a yam?
Check out my previous article: Rooting for Sweet Potatoes