Sweet potato slips are sprouts or cuttings taken directly from the mature sweet potato, which is a tuberous root. This planting method is preferred because it ensures the new plants are genetically identical to the parent, preserving the variety’s desired characteristics. Sweet potatoes are sensitive to cold, so planting must occur well after the last spring frost. The correct planting window is when the soil temperature has consistently warmed to at least 65°F, and ideally closer to 70°F, ensuring the plants have the heat required for vigorous growth.
Preparing the Slips and Planting Site
The small, young slips must be gradually introduced to the outdoor environment before transplanting, a process called hardening off. This involves placing the slips outside in a sheltered, partially shaded location for a few hours daily, slowly increasing exposure to direct sunlight and wind over seven to ten days. Hardening off strengthens the plant tissue, reducing the shock and severe wilting that occurs when tender slips are moved immediately into the garden. If your slips arrive bare-root and wilted, hardening off is still beneficial for establishment.
Sweet potatoes require loose, well-drained soil for the storage roots to expand. If native soil contains high clay content, amending it with organic matter like compost prevents compaction and improves drainage. The soil should be formed into raised mounds or continuous ridges. These raised structures, typically 6 to 8 inches high, allow the soil to warm up faster in the spring, which benefits this warm-season crop.
The mounds or ridges also provide an increased volume of loose soil for the developing storage roots, improving the ultimate shape and size of the harvest. The height of the ridges, which can be around 12 inches wide, also makes the eventual harvest easier by concentrating the crop. Avoid using soil excessively rich in nitrogen, as this encourages lush, sprawling vines at the expense of root production. The ideal soil pH for sweet potatoes is slightly acidic, ranging from 5.8 to 6.2.
Step-by-Step Guide to Setting Slips
When it is time to plant, choosing a warm, overcast day or planting late in the afternoon minimizes transplant shock from intense sun and heat. Slips should be planted deep enough to bury several nodes, which are the small bumps on the stem where leaves and roots emerge. New sweet potatoes form along these buried nodes, so adequate depth is tied directly to yield potential. A planting depth of about 4 inches is sufficient to cover the roots and one or two nodes of the stem, leaving only the top leaves above the soil line.
To set the slip, use a trowel, stick, or finger to create a hole in the top of the prepared mound, taking care not to disturb the ridge structure. Insert the slip, gently pushing it down until the lower leaves are just at or below the soil surface. If slips are long, pinch or break off the lower leaves so the stem can be buried deep enough. Once positioned, gently firm the soil around the stem to eliminate air pockets, but avoid compacting the soil, which restricts root growth.
Spacing is necessary to give plants room to grow and encourage the formation of larger storage roots. Individual slips should be spaced 12 to 18 inches apart along the top of the mound or ridge. If planting in rows, the distance between the center of each ridge should be 3 to 4 feet to accommodate the long, sprawling vines. Planting the slips in a zigzag pattern on wider mounds maximizes space use while allowing the plants to thrive.
Post-Planting Watering and Care
Immediately after planting, a deep and thorough initial watering is necessary to settle the soil around the slips and establish contact between the roots and the earth. This watering removes air pockets and ensures the young plant has immediate access to moisture. Although the slips may look wilted for the first few days—a normal reaction to transplanting—consistent moisture is required for the first seven to ten days to encourage root development and establishment.
During this initial establishment period, the soil should be kept uniformly moist, but never saturated, as excessive water leads to root rot. If planting occurs during intense heat or direct sun, providing temporary shade for the first two to three days reduces stress. Simple methods, such as placing upturned flower pots or wooden shingles over the slips during the hottest part of the day, protect them until they can withstand full sun. Once the slips have established themselves and show signs of new growth (after a week or two), reduce the watering frequency, focusing instead on deep, regular watering during dry periods.