Starting a sweet potato plant at home requires cultivating “slips,” which are the sprouts that grow from a mature sweet potato. The water-sprouting method is a simple and effective technique for home gardeners to produce these slips. Sweet potatoes are propagated vegetatively, meaning new plants grow from cuttings of the parent plant rather than from true seeds. This process allows gardeners to generate multiple young plants from a single root, providing a reliable start for the growing season.
Selecting the Ideal Sweet Potato
The success of your sprouting endeavor begins with choosing the right sweet potato. Select an organic sweet potato, as conventionally grown roots are often treated with sprout-inhibiting chemicals to extend their shelf life. These inhibitors can delay or prevent the formation of slips. Look for a firm, healthy root that shows no signs of decay, bruising, or mold.
The sweet potato has a distinct orientation, typically with a pointed end and a blunter end. The blunter end is where the slips, or sprouts, will primarily emerge, as it contains more nodes or “eyes.” Before placing the sweet potato in water, wash it to remove any surface dirt or lingering chemical residues. While cutting the potato in half increases the surface area for sprouting, a whole potato is less prone to rotting in the water.
Step-by-Step Water Sprouting Instructions
To begin the water sprouting process, use a clean glass jar or container large enough to hold half of the sweet potato submerged in water. Insert three to four wooden toothpicks horizontally around the middle of the sweet potato, spacing them evenly. These toothpicks act as a scaffold, resting on the rim of the jar and suspending the sweet potato. Submerge the bottom half, typically the pointed end, in the water, leaving the top half exposed to the air.
Place the assembled jar in a location that provides consistent warmth and bright, indirect light. Sweet potatoes are tropical plants and thrive in warm conditions, ideally between 75°F and 85°F. A bright windowsill that receives plenty of light but is shielded from harsh midday sun is appropriate. Direct, intense sunlight can overheat the water and stress the growing root.
The water must be maintained to prevent the sweet potato from rotting. Change the water every few days, or at least once a week, to keep it fresh and oxygenated. Using tap water is fine, but ensure it is not ice-cold when replenishing the jar. Small white roots should begin to form in the submerged section within a week or two. The first shoots, or slips, will emerge from the top surface in about four to eight weeks.
Harvesting and Preparing the Slips for Planting
Once the sweet potato has produced shoots, wait until they are robust enough to survive independently. Slips are ready for harvest when they are approximately four to six inches long and have developed several leaves. To remove the slip, gently twist or snap it off where it emerges from the mother sweet potato. Remove the entire shoot, ensuring no part of the slip’s stem remains attached to the original root.
The harvested slips, which are essentially unrooted cuttings, must be prepared for transplanting into soil. Place the separated slips into a new jar of fresh water, ensuring only the bottom portion of the stem is submerged. The leaves must remain above the waterline to prevent decay. If the slips are long, remove the lowest leaves so only the bare stem is in the water.
This rooting process allows the slips to develop independent root systems. Place this rooting jar in a bright location, similar to the mother potato. Roots will begin to emerge from the stems within a few days. The slips are ready for planting in the garden or a container once these new roots are about an inch long, providing a strong foundation for growth.
Troubleshooting Common Sprouting Problems
A common issue is the development of mold or rot on the sweet potato, often signaled by a foul odor or slimy texture in the water. This usually results from stagnant water or a cut surface on the potato. To remedy this, immediately change the water, trim away any visible soft or rotten tissue, and ensure you refresh the water every two to three days. Maintaining a warmer temperature helps the potato grow faster, which can outpace decay.
If weeks pass without any sign of growth, the primary cause is often a lack of warmth. Sweet potatoes require consistently high temperatures for metabolic processes to initiate sprouting. Move the jar to a warmer location, perhaps near a heat source or on a seedling heat mat, to stimulate growth. Failure to sprout can also be due to using a conventionally-grown potato that was heavily treated with sprout inhibitors.
Weak, pale, or “leggy” growth indicates the slips are not receiving enough light. Leggy slips have long, thin stems and small leaves, as the plant stretches in search of a light source. While sweet potatoes prefer bright, indirect light, a low-light environment results in poor growth. Move the jar to a spot that receives more intense light, such as under a grow light or in a sunnier window, to encourage stockier, healthier development.