Yes, you can plant a sprouted sweet potato, but the method is different from planting a standard potato. The correct way to propagate a sweet potato is by planting its sprouts, which are called “slips.” These slips are essentially rooted stem cuttings that grow directly from the stored sweet potato and are used to start the new plants. This process is necessary because planting the whole sweet potato root is ineffective and rarely produces a healthy, abundant harvest, while slips establish a strong, new plant.
Understanding Slips: Why You Can’t Plant the Whole Sweet Potato
Sweet potatoes are classified as storage roots, unlike white potatoes, which are true tubers. This distinction is the reason for the slip-planting method; the sweet potato is an enlarged lateral root used for energy storage, not a stem structure capable of generating multiple, independent plants. Planting the entire storage root often results in competitive growth or, more commonly, the root will simply rot before it can establish a new plant, especially if the environment is too cool or moist during spring planting.
The slips that grow from the sweet potato are stem sprouts, and each one is capable of developing its own root system and ultimately producing a new cluster of storage roots. This vegetative propagation method ensures the resulting plants are genetically identical to the parent sweet potato, guaranteeing a predictable harvest. By planting individual slips, you avoid the issues of tangled growth and competitive resource use that arise from trying to grow a single, massive root.
Step-by-Step Guide to Sprouting Slips
Generating slips requires starting the process indoors 8 to 10 weeks before the last expected spring frost date. One common method is the water and toothpick technique, where a sweet potato is partially submerged in water using toothpicks for support. The pointed, rooting end should be placed into the water, with the blunter end facing upward toward the light.
Another method is the bedding method, which involves partially burying the sweet potato horizontally in a container filled with moist soil or sand. Place the container in a warm, sunny location, or use a heating mat to keep the temperature between 75°F and 80°F. Within a few weeks, green shoots will emerge.
Allow shoots to grow until they are four to six inches long, the ideal size for a slip. Once they reach this height, carefully twist or cut the slip from the sweet potato at its base, ensuring no part of the original root is attached. Place the harvested slips in a jar of water, where they will quickly develop fibrous roots, making them ready for transplanting.
Transplanting Slips into the Garden
Sweet potato slips must be planted only after all danger of frost has passed and the soil temperature has warmed consistently to at least 65°F. This warmth is required, as sweet potatoes are a tropical crop and cannot tolerate cold soil. Before planting, slips grown indoors should be “hardened off” by gradually exposing them to outdoor conditions over the course of a week.
The ideal growing medium is a loose, sandy loam soil, which allows the storage roots to expand easily without resistance. Create planting mounds or rows that are six to eight inches high and spaced about three feet apart to accommodate the sprawling vines. Plant each slip deep enough so that the bottom half of the stem and at least two leaf nodes are buried beneath the soil surface.
The buried nodes are where the new storage roots will form, making deep planting essential for a good harvest. Immediately after planting, water the slips thoroughly to settle the soil around the developing roots. Keeping the soil consistently moist for the first seven to ten days helps the young slips establish themselves in their new environment.
Ongoing Care and Harvesting
Once established, sweet potato plants require deep, infrequent watering, especially during dry periods, to encourage the roots to grow downward. This plant is sensitive to drought for the first 50 to 60 days, but excessive moisture later in the season can cause the roots to split. Fertilization must focus on phosphorus and potassium rather than nitrogen, which encourages excessive vine growth at the expense of root development.
Avoid using high-nitrogen fertilizers or overly rich soil, as this leads to a lush, leafy plant with small storage roots. Plants require between 90 and 120 days to reach full maturity, depending on the variety and climate. A sign that harvest is approaching is when the leaves and ends of the vines begin to turn yellow.
Harvesting should take place before the first hard frost, as frost can damage the vines and allow decay to travel down to the storage roots. Use a garden fork to loosen the soil about 18 inches around the main crown, gently lifting the sweet potatoes. After harvest, the roots benefit from a curing period in a warm, humid location (around 75°F to 80°F) for several days. Curing improves flavor and storage life by converting starches into sugars.