Sweet potatoes are a warm-weather crop requiring a long, consistently warm growing season to produce edible storage roots. These plants are extremely sensitive to cold and require specific soil conditions to thrive in Alabama’s climate. Focusing on the right moment to transplant the young sprouts, known as slips, is the most important factor for a bountiful harvest. Ignoring the proper planting window can result in stunted growth or crop failure.
The Critical Planting Window
Planting sweet potatoes is determined by the temperature of the soil itself, not the last spring air frost date. The ground must be consistently warm, maintaining at least 65°F for the slips to establish roots successfully. A soil thermometer is a valuable tool for confirming this temperature threshold before planting.
The general calendar window for planting in Alabama extends from mid-April through late June, but this timing must be adjusted based on the state’s geographical regions. Gardeners in South Alabama, where the climate warms earliest, can typically begin planting around late April or early May.
Moving north into Central Alabama, the planting window shifts later, generally starting in mid-May. Northern parts of the state often do not reach the required 65°F until late May or early June. Planting too early into cold soil can cause the tender slips to rot or fail to grow.
Essential Site and Slip Preparation
Before planting, the site and the slips require specific preparation. Sweet potatoes develop best in loose, well-drained, sandy loam soil; heavy clay should be avoided because it holds too much moisture and encourages root rot. Optimal soil conditions include a slightly acidic pH, ideally ranging between 5.8 and 6.2, which should be confirmed with a soil test.
Sweet potatoes are grown from slips, which are young vine cuttings taken from a mature root. These slips are often shipped without soil and may arrive looking wilted or stressed, which is a normal response to shipping. It is important to plant them as soon as possible after they arrive.
If the soil is not yet warm enough, the slips should not be stored in water but instead “heeled in.” This means loosely planting them in a tray of moist potting mix or sand in a warm location. This temporary step helps the slips recover from transplant shock and begin to develop small roots before they are set into the final garden bed. Handling the slips gently minimizes stress and prepares them for the permanent planting site.
Planting Techniques for Successful Establishment
Planting the slips is best accomplished by building raised beds or mounds. Mounds that are 8 to 12 inches high promote excellent drainage, which is necessary to prevent the storage roots from rotting in saturated soil. This technique also allows the soil to warm up faster in the spring and simplifies the harvesting process later in the season.
Slips should be spaced 12 to 18 inches apart within the mounds, with ample room left between rows for the long vines to run. When transplanting, the entire lower half of the slip, including the nodes where new roots will form, needs to be buried in the soil. This means setting the slip about 2 to 4 inches deep, leaving only the top cluster of leaves exposed above the soil line.
Immediately following the placement of the slips, a deep, thorough watering is necessary to settle the soil and help the plants overcome transplant shock. For the first seven to ten days after planting, the slips require generous and consistent watering to establish a strong root system. Maintaining this moisture is necessary for the initial survival and vigorous growth of the young sweet potato plants.