A sweet potato slip is a vine cutting or a rooted sprout grown directly from a mature sweet potato tuber. This vegetative propagation method is the standard way to start a new sweet potato crop, rather than planting the whole tuber or true seeds. The sweet potato vine (Ipomoea batatas) is a tropical plant that cannot tolerate cold soil temperatures early in the season. Using slips allows the gardener to start the plants indoors in a warm environment and transplant them only when the soil is sufficiently warm for immediate growth.
Commercial Sources for Buying Slips
Acquiring slips commercially offers convenience and access to certified, disease-free plant material. Gardeners can choose between local sources and mail-order vendors. Local nurseries, garden centers, and farmers markets provide the benefit of immediate availability, allowing you to visually inspect the slips before purchase. This is helpful if you have a short planting window or need to replace lost plants quickly.
The alternative is purchasing slips from specialized mail-order seed companies, which offer a much wider selection of varieties (e.g., ‘Beauregard,’ ‘Covington,’ or ‘Murasaki’). These companies ship the slips at the appropriate time for your planting zone, often in bundles of 10 to 25. Mail-order guarantees genetic purity and often provides certified stock inspected for pests and diseases, but you must order months ahead of the planting season. Slips may arrive wilted from transit, requiring immediate attention to revive them before planting.
Creating Slips from a Whole Sweet Potato
The most economical way to obtain a large number of slips is to sprout them yourself from a whole sweet potato tuber, often called a “mother.” This propagation should begin approximately six to eight weeks before your anticipated planting date. Lay the tuber horizontally in a shallow tray filled with a moist, soilless growing medium, burying it halfway. Using an organic tuber is recommended, as conventionally grown sweet potatoes may have been treated with sprout-inhibiting chemicals.
Place the tray in a warm location, ideally maintaining a temperature around 80°F, and keep the medium consistently damp but not waterlogged to prevent rot. Within three to four weeks, numerous shoots will emerge from the tuber’s surface. Once these sprouts, or slips, reach a length of about six inches and have several leaves, they are ready to be harvested. Gently twist or cut the slips away from the mother tuber.
After separating the slips, place the cut ends in a jar of water or directly into a small pot of moist potting mix to encourage root development. If rooting in water, change the water every few days to maintain sanitation and prevent rot. This rooting process takes about one to two weeks. The presence of small white, fibrous roots signals they are ready for planting. A single healthy sweet potato can yield over a dozen viable slips.
Selecting the Right Time and Quality
Timing the acquisition of slips is determined by the required soil temperature for successful establishment. Sweet potatoes are sensitive to cold, so slips should only be planted when the soil temperature consistently registers above 60°F, ideally closer to 70°F. This usually occurs two to four weeks after the final spring frost date. Acquiring or harvesting slips too early necessitates temporary holding, which introduces unnecessary stress to the young plants.
Healthy slips exhibit specific characteristics that indicate their quality and vigor. Look for slips with strong, thick stems, a good number of healthy leaves, and no signs of yellowing or pest damage. Slips six to twelve inches long are ideal for transplanting. If the slips have already developed fine, white roots, they will establish themselves much faster once placed in the garden bed.
Immediate Care After Acquisition
Once slips are acquired, immediate attention is required to ensure their survival. If shipped, bare-root slips may appear limp or stressed; remove them from their packaging immediately to allow air circulation. If you cannot plant them right away, temporarily “heel them in” by loosely planting the root ends in moist potting mix, or place the cut ends in a glass of water for no more than a few days.
A process called “hardening off” is necessary for any slips grown entirely indoors or shipped from a protected environment. This gradually acclimates the young plants to outdoor conditions like direct sunlight, wind, and temperature fluctuations. Begin by placing the slips outdoors in a shaded location for a few hours each day. Over five to seven days, progressively increase the duration of their outdoor exposure and the intensity of the light they receive. This conditioning minimizes transplant shock and prepares the slips for vigorous growth.