Sweet potatoes are a warm-season crop that demands a long, hot growing period to produce their fleshy, edible storage roots. This tropical plant is extremely sensitive to cold, making precise planting timing necessary for success in Arkansas’s varied climate. Correctly gauging the soil’s readiness is crucial. Planting the young sprouts, known as slips, too early can stunt growth or lead to chilling injury, while planting too late may prevent the roots from fully maturing before the first fall frost.
The Critical Planting Window in Arkansas
The primary factor determining the correct planting time is the soil temperature, which must be consistently warm for the slips to establish roots quickly. Planting should only occur when the soil temperature, measured at a four-inch depth, is steadily 60°F or higher, with an ideal range closer to 65°F. Planting when the soil is below 55°F can cause chilling damage to the slips, leading to poor growth and low yields.
Arkansas’s geography means the planting window varies significantly from south to north. Gardeners in Southern Arkansas, which experiences warmer conditions earlier, can typically begin planting from mid-to-late April through mid-May. In Central Arkansas, the recommended planting period shifts slightly later, spanning from late April to late May.
In the cooler Northern Arkansas and Ozark regions, the safe window for planting is usually delayed until May, often starting around the first of the month and extending through the end of May. Waiting past the last predicted spring frost is mandatory, as sweet potatoes cannot tolerate frost exposure. Early planting is a strong predictor of higher total yields, particularly because it allows for a longer period of root development.
Preparing the Slips and Soil
Successful sweet potato production requires attention to both the planting material and the bed preparation. Slips are the sprouts cut from a mature sweet potato; they must be healthy, disease-free, and approximately eight to ten inches long before transplanting. If growing your own slips, cut them an inch above the soil line of the bedding material to avoid transferring soil-borne diseases.
The planting bed must be prepared to create the optimal environment for the storage roots to form. Sweet potatoes thrive in well-drained, light, sandy loam soil, with a slightly acidic pH between 5.7 and 6.7. The soil should be worked into raised beds or hills, typically about eight inches high, which helps the soil warm up faster and provides the loose structure necessary for root expansion.
It is important to apply compost or a complete fertilizer before planting, but growers must avoid high-nitrogen formulas. Excessive nitrogen encourages the plant to produce lush, leafy vines at the expense of developing the storage roots. A soil test can provide specific recommendations for the appropriate balance of phosphorus and potassium, which are more beneficial for root formation.
Planting Techniques and Initial Care
The actual planting process involves setting the slips into the prepared hills or rows and ensuring they receive immediate and adequate moisture. Slips should be planted 12 to 18 inches apart, with rows spaced about three feet apart to allow room for the sprawling vines. To encourage root development along the stem, the slips are set deep enough to cover the roots and the stem up to the top few leaves.
Planting is best done on a warm, overcast day to minimize transplant shock, though the young plants may still wilt initially. Immediately after planting, the slips require generous, deep watering to help them establish their root systems. This consistent moisture level is important during the first week and throughout the first 30 days, as this is the critical period for the development of the storage roots.
During this establishment phase, the soil should be kept consistently moist but never waterlogged, which can lead to root rot. Deep watering is preferable to shallow, frequent watering because it encourages the roots to grow deeper and become more robust. Maintaining this careful balance of moisture helps the young plants overcome transplant shock and begin vigorous growth.
Ongoing Care and Harvesting Timelines
Once the sweet potato slips are established, their watering needs change, and they become relatively low-maintenance, heat-tolerant plants. They generally require about one to one and a half inches of water per week, including rainfall, during the main growing season. As the vines begin to cover the soil, their dense foliage helps suppress weeds, but applying organic mulch can further help retain soil moisture and regulate temperature.
As the plants mature, it is necessary to reduce watering about three to four weeks before the anticipated digging. This reduction in moisture helps the sweet potatoes mature, prevents the roots from cracking, and concentrates the natural sugars within the tubers. The roots are typically ready for harvest between 90 and 120 days after planting, which often falls between late August and October in Arkansas, depending on the variety.
The most important consideration for harvest is to dig the sweet potatoes before the first hard frost, as cold soil temperatures below 55°F can damage the flavor and storage quality of the roots. After gently digging the roots and brushing off excess soil, they must undergo a curing process to heal any minor cuts and convert starches to sugars. Curing involves holding the roots at a high temperature, ideally 80°F to 85°F, and high humidity for about four to fourteen days to ensure they store well and develop their characteristic sweetness.