Why Start Your Own Sweet Potato Slips?
Growing your own sweet potatoes begins with a simple but crucial step: producing slips. These are the rooted sprouts that will eventually become your harvest. Many gardeners purchase slips from nurseries, but starting them yourself is surprisingly easy and offers several advantages. You save money, you know exactly how your plants were treated, and you can choose the exact variety you want. The process of growing sweet potato slips is a rewarding project that connects you more deeply with your garden from the very start.
Unlike standard potatoes, which grow from eyes on the tuber, sweet potatoes require a different approach. They do not have these ready-made growing points. Instead, you coax roots and sprouts from the skin of the potato itself. This method works because sweet potato skins contain fine, latent roots, much like those found on carrots or beets. With the right warmth and moisture, these dormant cells spring to life.
Timing and Temperature for Success
Sweet potatoes are true warm-weather crops. They thrive when the air and soil are consistently warm. Getting the timing right for growing sweet potato slips is half the battle. You need to plan backward from your last expected frost date. The soil in your garden must reach at least 60°F before you can transplant your slips outside. Planting them into cold earth stunts their growth and can kill the tender vines.
The method you choose dictates your timeline. If you start slips in water, allow about six to seven weeks before they are ready for the garden. Starting them in soil is a bit faster, taking roughly four to six weeks. Mark your calendar. A common mistake is rushing this process. Patience during the slip-making stage leads to stronger plants and a more abundant harvest later in the season.
Selecting the Right Sweet Potato
You can start slips from a store-bought sweet potato or one you saved from your own previous harvest. The key is choosing a healthy, untreated tuber. Many grocery store sweet potatoes are sprayed with a sprout inhibitor to keep them shelf-stable. These treated potatoes will struggle to produce slips. Look for organic sweet potatoes, which are far less likely to have been treated.
Sweet Potatoes Versus Yams
Grocery stores often label sweet potatoes as yams, but botanically they are different plants. True yams are starchier and have rough, bark-like skin. For the purpose of growing sweet potato slips, you want a true sweet potato. It typically has smoother skin and a deeper orange or purple flesh. The variety you choose will affect the flavor and texture of your final crop, so pick one you enjoy eating.
Method One: Growing Slips in Water
This is the classic, most popular method for growing sweet potato slips. It is visual, simple, and requires only a few household items. You will need a clear glass or jar, clean water, a few toothpicks, and your sweet potato. The clear glass is important because it lets light reach the developing roots, which encourages faster growth.
Step-by-Step Water Method
Fill your glass about halfway with room-temperature water. Identify the tapered, narrow end of the sweet potato. This is the rooting end. Insert three or four toothpicks around the middle of the potato, spaced evenly. Rest the toothpicks on the rim of the glass so that the tapered end is submerged in the water. The top half of the potato should remain dry and exposed to the air.
Place the glass on a sunny windowsill. Warmth is critical, so a south-facing window works best. Change the water every week to prevent stagnation and bacterial growth. Within a few weeks, you will see fuzzy white roots forming in the water. Shortly after, small green sprouts will emerge from the top of the potato above the water line.
Harvesting and Rooting the Slips
Wait until the sprouts are about four to five inches long. Then, gently twist or cut them off at the base where they attach to the potato. Place each sprout in a separate glass of fresh water. Submerge only the bottom inch or two of the stem. Within a day or two, tiny roots will appear at the base of the slip. Once these roots are about an inch long, the slip is ready for transplanting into your garden.
The Gift of Continuous Slips
One of the best parts of the water method is that the original potato keeps producing. After you remove the first batch of slips, return the potato to a fresh glass of water. It will continue to generate new sprouts for several weeks, depending on its size and energy reserves. This means you can produce a steady supply of slips without needing a new potato each time. You can easily create dozens of plants from a single tuber.
Method Two: Growing Slips Directly in Garden Soil
If you live in a region with a long, warm growing season, you can start slips directly in the garden. This method saves indoor space and avoids the step of transplanting from a jar. However, it requires patience and the right weather conditions. Your soil temperature must be at least 65°F, and the air should be consistently warm with no risk of frost.
How to Plant in the Garden
Choose a sunny spot with well-draining soil. Bury the tapered, rooting end of the sweet potato so that the bottom half is covered with soil. The top half should remain above ground. Water the area gently to settle the soil. Do not bury the potato too deeply, as this increases the risk of rot.
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Check for roots after about one to two weeks. Give the potato a gentle tug. If you feel resistance, roots have formed. Soon after, the exposed top half will send up green shoots. When these shoots reach four to five inches tall, you can remove them by twisting or cutting them at the base. Remove the lower leaves from each slip, then place the slips in a jar of water to develop their own roots. This takes only a day or two. Once roots appear, transplant the slips to their final spacing in the garden.
The Risk of Rot in Soil
A significant drawback of starting slips in soil, whether in the garden or in a container indoors, is the potential for rot. Sweet potatoes are prone to rotting if they are buried too deep, if the rooting end is damaged during planting, or if the soil stays too wet. If your potato rots, you must discard it and begin again with a fresh tuber. This can be frustrating, especially after waiting several weeks. The water method largely avoids this risk because the potato is only partially submerged and the water is changed regularly.
Method Three: Growing Slips in Soil Indoors
This approach combines the control of an indoor environment with the stability of soil. It is a great option if you want faster results than the water method but lack a long outdoor growing season. You will need a shallow container with drainage holes, a high-quality potting mix, and your sweet potato.
Setting Up Your Indoor Bed
Fill your container with moistened potting soil. Do not pack it down. Lay the sweet potato lengthwise on its side, burying it about halfway into the soil. The top half should remain exposed. Place the container in a warm, sunny location. A heat mat placed under the container can speed up the process, as sweet potatoes love bottom heat.
Keep the soil consistently moist but not soggy. Waterlogged conditions invite rot. Within about a week, roots will begin to grow into the soil. In another week or two, sprouts will emerge from the exposed top of the potato. This method is generally faster than the water method because the roots have immediate access to nutrients and a stable environment.
Harvesting Soil-Started Slips
When the sprouts are four to five inches tall, they are ready to be removed. If a slip has its own roots attached when you pull it from the soil, you can transplant it directly into the garden. If it does not have roots, place it in a glass of water for a day or two until roots form. This method produces sturdy slips that often transplant with less shock than those grown entirely in water.
Transplanting Your Slips into the Garden
Once your slips have a healthy set of roots, it is time to move them outdoors. Harden them off by placing them outside in a sheltered spot for a few hours each day over the course of a week. This acclimates them to wind and direct sunlight. Choose a cloudy day or late afternoon for transplanting to reduce stress on the young plants.
Dig holes that are deep enough to cover the roots and the lower part of the stem, up to the first set of leaves. Space your slips about 12 to 18 inches apart in rows. Sweet potatoes need room to spread their vines and develop large tubers. Water them in well after planting. Keep the soil evenly moist for the first week while they establish.
