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Planting Sweet Potatoes After Their Eyes Are Out

Native to the tropics, sweet potatoes (Ipomoea batatas) need four months of warm weather to produce their sweet orange, or in some cases, yellow or white tubers. Hardy only in U.S. Department of Agriculture plant hardiness zones 9 through 11, they are treated elsewhere as warm-season annuals from slips that you can buy or grow yourself. If growing your own, plan on starting them indoors at least eight weeks before the last spring frost date for your area. An average-sized sweet potato can yield up to 12 new plants from sprouts that grow from the eyes.

  1. Sprouting Basics

    • Like white potatoes, sweet potatoes develop eyes along their mature tubers that must be sprouted before being planted. But growing your own sweet potatoes requires more than simply cutting an eye off the tuber or planting the whole tuber, as it must develop a vascular system before it's planted into the ground. If planted whole, once the eyes have sprouted, a sweet potato tuber will rot in the soil before the sprouts, or slips, have time to send down roots and become fully established.

    Sprouting Method

    • Before sprouting your sweet potatoes, cure them for a day or two by placing them, uncovered, in an area with a temperature of 80 to 85 degrees Fahrenheit. This promotes the growth of a second skin that creates a barrier against moisture and impurities. Place the cured tubers in buckets of sand, sawdust or a combination of peat moss and potting soil, and keep the medium damp but not saturated. Place the pots in a bright spot at a minimum temperature of 75 to 80 F. An alternate method of sprouting sweet potatoes is to place them containers filled halfway up the tubers with water. Replenish the water as needed, and change it completely every few days or whenever it becomes cloudy.

    What to Look For

    • New sweet potato sprouts appear as pale greenish-white shoots. When the new slips have grown to about 8 or 9 inches and bear several leaves, it's time to separate them from the parent tuber. Cut the slips off, leaving them attached to a small piece of skin, and place them immediately into fresh soil or in jars of water. Place them in the soil up to just below the leaves, or in water up to that point. Once roots appear, the slips can be safely transferred to the garden once the soil has warmed to at least 60 F. You can also let the slips keep growing in the pots or jars if you're not ready to plant them outside right away.

    The Planting Process

    • Select a well-draining spot that receives full sun all day. Dig the garden bed down to 6 to 12 inches, and enrich the soil with lots of organic matter in the form of mature compost or aged animal manure. Loose, stone-free soil allows the tubers to develop without deformities. For each slip, dig a hole deep enough to allow you to plant it up to just below the leaves, and bring the soil lightly around the stem. Space the slips about 12 to 18 inches apart, and as they develop, bring more soil up around them. Water at planting time and whenever the soil appears dry 1 inch below the surface.