Sweet potatoes are grown from vegetative cuttings called slips, not from seeds or the tubers themselves. These slips are small, sprouted plants that ensure the new crop retains the same traits as the parent sweet potato. Using slips is the standard and most reliable method for propagation. Understanding the visual characteristics of a high-quality slip is important, as this planting material establishes the entire harvest.
Defining the Sweet Potato Slip
A sweet potato slip is a sprout or shoot that develops directly from the storage root (the tuber). These young plants are derived through asexual reproduction, making them genetic clones of the mother potato. Slips are distinct from vine cuttings taken later in the season from established plants.
Gardeners generate slips by placing a mature sweet potato in warm, moist conditions, such as partially submerged in water or buried in damp soil. The warmth and moisture stimulate the tuber to produce small shoots from its dormant buds or “eyes.” This process, often called “bedding,” takes several weeks until the shoots are suitable for removal.
Once the shoots are approximately four to six inches long, they are separated from the parent tuber to become individual slips. When placed in the ground, this small, complete plant will develop its own storage roots, which eventually become the new sweet potatoes.
Key Visual Characteristics of a Ready Slip
A slip is ready for planting when it exhibits a specific combination of size, stem strength, and root development. The ideal height for a transplantable slip is six to twelve inches. This size ensures the plant has enough energy and leaf surface area to begin photosynthesis quickly after transplanting.
The stem should be firm, unbroken, and reasonably thick, avoiding a spindly or weak appearance. While the color varies by variety—ranging from bright green to having purple or reddish tinges—a uniform, vibrant color is a sign of health. A strong stem is necessary to support the plant and resist damage during handling and planting.
A ready slip features several healthy leaves, often between four and six, which should be a deep, rich green color and fully expanded. These leaves provide the energy needed for the plant to establish itself in the soil. The presence of small, white, fibrous adventitious roots at the base of the slip is the most reliable sign of readiness, allowing the slip to immediately begin absorbing water and nutrients once planted.
Identifying and Avoiding Poor Quality Slips
Inspecting slips for signs of disease, stress, or poor development prevents planting material that will struggle to produce a crop. A serious visual concern is the presence of fungal diseases, such as black rot, which appears as dark, sunken lesions or black spots on the stem. Any slip showing signs of discolored or wet-looking areas should be discarded immediately to prevent introducing pathogens.
Slips grown in insufficient light or excessive heat often become “leggy,” appearing too long and thin with widely spaced nodes. These elongated slips result in weak stems that transplant poorly and are slow to recover. Additionally, pale green or yellow leaves (chlorosis) indicate nutrient deficiency or significant stress, suggesting the slip is not vigorous enough for planting.
Physical damage from shipping or handling can also render a slip unusable, such as a completely broken stem or severely wilted, dried, or dead leaves. While some wilting upon arrival is normal, planting slips with intact, firm stems and a few healthy leaves provides the best chance for successful and rapid growth.