Sweet potatoes are propagated using “slips,” which are sprouts that grow from the parent root, rather than being grown from a seed or whole tuber like a common potato. Growing slips in water is a popular method for home gardeners to start plants or cultivate an attractive, vining houseplant. Success relies on correctly orienting the sweet potato in the water to encourage both root development and the emergence of these new shoots.
Identifying the Proper Orientation
Determining which side of the sweet potato should be submerged is the most important step for successfully growing slips. The sweet potato, which is botanically a storage root, has a distinct polarity, featuring a root end and a stem end. The stem end produces the slips (sprouts), while the root end develops new roots.
The root end is typically the more tapered or pointed side, and you may sometimes observe small, fine roots present on this end. The stem end, where the vine was attached to the plant, is often the more blunt, rounded, or slightly scarred side. This is where the new green shoots will emerge. For the water method to work, the root end must be placed into the water, and the stem end must be left exposed to the air.
The Sprouting Setup
Once the root and stem ends are identified, the next step is to create a secure setup to suspend the sweet potato in a container of water. The most common tool for this suspension is a set of wooden toothpicks. Insert three to four toothpicks around the sweet potato’s middle, spacing them evenly, to act as a support structure.
Insert the toothpicks just deep enough to hold the potato’s weight without cracking the skin. Place the sweet potato into a clear glass or jar, resting the toothpicks on the rim. The goal is to submerge the bottom third to half of the root end in the water while leaving the stem end completely dry and exposed above the water line. This partial submersion allows the root end to draw in moisture while preventing the entire vegetable from rotting.
Ongoing Care and Monitoring
After the sweet potato is suspended in water, place it in an optimal environment to encourage growth. Sweet potatoes thrive with warmth and bright light, so a sunny windowsill is ideal. However, direct, intense sunlight can sometimes overheat the water, so ensure the water temperature remains consistently warm, as sweet potatoes are tropical plants.
Regular maintenance is necessary for a healthy setup, involving changing the water every few days to a week. Stagnant water can quickly become cloudy, harbor bacteria, or promote mold growth on the submerged portion of the potato. Fresh water provides necessary oxygen and reduces the risk of decay. Within a few weeks, you should observe thin, white roots forming underwater and small green or purple sprouts emerging from the exposed stem end.
Harvesting the Slips
Sweet potato slips are ready for harvesting once they have grown to a sufficient size and matured slightly. The ideal length is between four to six inches, which ensures the slip has enough stored energy for the next stage of growth. When they reach this size, gently twist or pull them off the parent sweet potato at the point where they emerge.
The removed slips should then be placed into a separate container of water to develop independent root systems. Remove the bottom leaves, leaving only the stem submerged in the water to prevent decay. These slips will rapidly grow a dense cluster of roots, often within a week or two, making them ready to be planted directly into soil.