A sweet potato slip is a rooted sprout or vine cutting taken from a mature sweet potato, serving as the primary method of propagation. These slips are transplanted into the garden to grow the storage roots that become the harvested sweet potatoes. The final yield from one slip is highly variable, depending on environmental conditions and gardening practices throughout the growing season. Sweet potatoes are a tropical, warm-season crop that thrives in long, hot summers, requiring specific attention to warmth. Understanding the factors that determine the final harvest is key to maximizing the yield from each planted slip.
Typical Yield Expectations
A single sweet potato slip typically yields a harvest ranging from one to five pounds of marketable sweet potatoes per plant. A healthy, well-maintained plant will generally produce between four and ten storage roots of a usable size. This wide range reflects the influence of factors like soil fertility, variety selection, and the length of the growing season.
Yields on the higher end often result from optimal conditions, including a long period of warm soil and consistent moisture. Conversely, a shorter season or less-than-ideal soil conditions may result in a harvest closer to the lower end, with fewer and smaller potatoes. The genetic traits of the specific variety planted also determine the size and number of tubers formed.
Key Factors Influencing Tuber Production
Spacing and Soil
Achieving maximum yield requires careful management, starting with correct spacing. Sweet potato plants need adequate room to allow storage roots to swell without competing for resources. Planting slips 12 to 18 inches apart within rows is recommended, with rows spaced three to four feet apart to accommodate the sprawling vines.
The composition of the soil is also influential, as sweet potatoes perform best in a loose, well-drained, light, sandy loam. Heavier clay-based soils can restrict root expansion, potentially leading to misshapen or smaller harvests. Gardeners must also avoid excessive nitrogen, which encourages vigorous vine growth at the expense of tuber development below the soil.
Environment and Variety
Sweet potatoes are highly dependent on warmth and sunlight for optimal root formation, requiring at least six hours of direct sunlight daily. Consistent moisture is necessary, especially during the initial establishment phase and when tubers begin to enlarge. Providing about one inch of water per week is a good guideline once the plants are established.
Variety selection also dictates the final yield, as different cultivars possess varying growth habits and maturity rates. For example, the popular ‘Beauregard’ variety is known for its high yield potential and relatively early maturity (around 90 days). Selecting a variety suited to the local climate and desired harvest window is essential for a successful outcome.
Essential Steps for Planting Slips
Planting should only occur after the last frost has passed and the soil temperature consistently registers above 60°F, ideally 65°F. Planting too early can severely stunt growth and reduce the final yield, as sweet potatoes are extremely sensitive to cold. Before transplanting, “harden off” the slips by gradually exposing them to outdoor conditions over a week or two.
The planting bed requires creating raised mounds or ridges six to eight inches high. This technique allows the soil to warm faster and provides the necessary loose medium for root expansion. When placing the slip, set it deep enough so that at least two nodes are covered by the soil, typically planting the slip two to three inches deep.
Remove the lower leaves from the slip, leaving only the top leaves intact above the soil line. Immediately following placement, the new slips require deep watering to settle the soil and minimize transplant shock. Maintaining consistent moisture for the first week is necessary to ensure successful rooting and establishment.
Harvesting and Curing for Best Results
Sweet potatoes require 90 to 120 days to reach maturity. The goal is to harvest before the soil temperature drops below 55°F, meaning they must be dug up before the first hard frost. A few days before harvest, cutting the vines back to the soil line helps the potato skin set and reduces the chance of damage during digging.
Harvesting requires a careful approach because the skin of a freshly dug sweet potato is thin and easily bruised. Begin digging 12 to 18 inches away from the main stem to avoid slicing the storage roots. Using a garden fork to gently loosen the soil and lift the potatoes is recommended over using a shovel.
The most important step after digging is curing, which improves both flavor and storage life. Curing involves holding the sweet potatoes at 80 to 85°F with high humidity (85% to 95%) for four to fourteen days. This warmth converts starches into sugars, enhancing sweetness, while the humidity encourages the formation of a protective “wound cork” to heal minor cuts.