Sweet potatoes are warm-weather vegetables grown from “slips,” which are the vegetative sprouts that emerge from the mature tuberous root. Unlike regular potatoes, sweet potatoes are not grown by planting the whole root or pieces of it, as this would produce a crowded, low-yield crop. The process of sprouting a sweet potato is the first step in propagating these slips, creating the necessary starts to grow a new, productive plant in the garden. This method allows a single sweet potato to yield numerous plant starts efficiently.
Selecting the Right Sweet Potato and Necessary Supplies
Choosing the right sweet potato is the first step toward a successful crop, and not all store-bought roots are suitable. Select a firm, unblemished sweet potato that shows no signs of soft spots, mold, or wrinkling. It is helpful to choose an organic sweet potato since conventionally grown ones are sometimes treated with a growth inhibitor to prevent sprouting during storage. These growth inhibitors can significantly slow down or prevent the emergence of slips. A medium-sized sweet potato, about two inches in diameter, is generally sufficient for producing a good number of sprouts. Along with the sweet potato, you will need a clear glass jar narrow enough for the potato to rest on the rim, three or four sturdy wooden toothpicks, and clean water.
Step-by-Step Guide to Water Sprouting
The water-sprouting method uses the sweet potato as a nutrient source, encouraging it to produce vegetative growth. To begin, identify the “sprouting end,” which is often the more pointed end or the end with the most small bumps, or “eyes.” Insert three or four toothpicks horizontally around the middle circumference of the sweet potato, spacing them evenly to act as supports.
The toothpicks should be pushed deep enough into the flesh to hold the sweet potato securely on the rim of the jar. Place the sweet potato into the jar with the sprouting end pointing up and the opposite end submerged in water. The water level should cover only the bottom third to half of the root, leaving the main body and the top exposed to air.
Position the jar in a location that receives bright, indirect sunlight and maintains a consistently warm temperature, ideally around 75 to 85 degrees Fahrenheit. The warmth is important for stimulating the root to exit its dormant state and begin producing shoots.
Change the water every few days to prevent the growth of mold, bacteria, or algae, which could cause the sweet potato to rot. Small roots will begin to emerge from the submerged end of the sweet potato, usually within a week or two. Shoots, known as slips, will then begin to emerge from the top and sides of the potato after about three to six weeks.
Harvesting and Planting the Sweet Potato Slips
Harvesting and Rooting Slips
Once the slips have grown to a length of about four to six inches, they are ready to be harvested from the parent sweet potato. To ensure the new plant has the best chance of survival, remove the slips by gently twisting or cutting them off precisely at the point where they emerge. Avoid tearing the slips, as this can damage the parent root and the slip itself.
The slips must develop their own root system before being planted in soil. Place the harvested slips into a separate container of water, ensuring that only the bottom two inches of the stem are submerged. Remove any leaves that would sit below the waterline. Within one to two weeks, the submerged stems will develop a cluster of fine, white roots.
Final Planting
The slips are ready for final planting when the roots are several inches long and well-established. Sweet potatoes are highly sensitive to cold, so they should only be planted outdoors when all risk of frost has passed and the soil temperature is consistently above 60 degrees Fahrenheit. Plant the rooted slips deep into the garden soil or container, burying the stem up to the level of the leaves. The nodes along the buried stem are where the new sweet potatoes will form, making deep planting a necessary step for a substantial harvest.