Sweet Potato Fertilizer Requirements: Growing Guide Donna Larson, February 23, 2024February 23, 2024 We’re planning our summer garden spaces, and that means starting our sweet potato slips. Let’s look at the sweet potato fertilizer requirements and growing conditions needed for a successful crop. Jump to Sweet Potato Fertilizer Requirements Facts About Sweet Potato Plants Common Name: Sweet Potato Scientific Name: Ipomoea Batatas Family: Morning Glory Perennial Hardiness Zone: Zones 8 to 11 Light Requirement: Full Sun Soil: Well-drained soil / sand Nutrient Requirements: low nitrogen, light feeder Water: Regular, at Least 1 Inch Per Week Propagation: Slips / Vine Cuttings Varieties of Sweet Potatoes As always, I say check with your local extension office to see what sweet potato varieties they recommend for your area. Here in zone 9a, The University of Florida Extension states that “Centennial’ and ‘Beauregard’ are two varieties that grow well in Florida gardens. Gardeners with less space should consider ‘Vardaman’, a bush type of sweet potato that’s great for smaller gardens.” Personally, I’m going to experiment with these plus the Georgia Jet this year to see which one does best in my own growing space. All About Planting Sweet Potatoes From planting to harvest, they’re far different than regular potatoes, which are in the nightshade family. Let’s cover all of the details, not just sweet potato fertilizer requirements, on how to grow these tasty root vegetables. Climate Being native to Central or South America, sweet potatoes are a staple crop to most southern gardeners. They love the hot weather, unlike many of our other root vegetables. We can pretty much plant our sweet potato crops and forget about them for the season. They’re very low maintenance, and they provide summertime greens for us when it’s too hot for most other leafy greens. Planting Time We usually plant “slips” into the ground to grow our sweet potatoes. Slips are just pieces of vine that have been rooted in water or soil. They will grow well in warm soil temperatures, so we usually plant slips in Spring. After the danger of frost has past, it’s safe to move your slips outside and into the soil. You may continue to plant them into Summer, but make sure that you have enough frost free days left to grow them when you put them in the ground. Where to Plant Them Make sure to plant your sweet potatoes in full sun, giving them at least 4-6 hours of sunlight per day. Sweet potatoes require so much sunlight so they can photosynthesize efficiently. Sweet potatoes planted in full sun typically produce more and larger tubers compared to those planted in shaded areas. More sunlight also helps to prevent disease amongst the vines. Soil Type Sandy soil is the favorite of the sweet potato, which is just another reason they’re so easy for us to grow here in the South. The tubers don’t like resistance to grow against, so the sand works well for them. Additionally, well-drained soil prevents water from pooling around the roots of the sweet potato plants, reducing the risk of root rot and other water-related diseases. Sandy soil allows for better aeration, meaning air can easily penetrate the soil and reach the roots. The loose texture of sandy soil allows for easier digging and harvesting of the tubers without causing damage. Spacing Sweet potato plants should be spaced about 3 to 4 feet apart in rows. This wide spacing allows the plants ample room to spread out as they grow, preventing overcrowding and competition for resources such as sunlight, water, and nutrients. Within each row, create mounds or hills spaced about 12 to 18 inches apart. Each hill should accommodate one or two sweet potato slips or cuttings. Plant sweet potato slips or cuttings deep enough so that only the top few leaves are above the soil surface. Burying the stems up to the leaves encourages the development of additional roots along the stem, which can lead to increased tuber production. Watering Proper watering is essential for the successful growth of sweet potatoes. They require consistent moisture throughout the growing season, particularly during the initial stages of growth and tuber development. Aim to keep the soil evenly moist, but not waterlogged, as excessive moisture can lead to root rot and other fungal diseases. When watering sweet potatoes, it’s important to water deeply to encourage plants to grow a deep and extensive root system. Water should make it through the soil to a depth of at least 6 to 8 inches to ensure that the roots can access moisture effectively. Avoid watering late in the evening, as this can create a damp environment that is encourages the spread of disease. During periods of heavy rainfall, you may need to adjust your watering schedule to avoid waterlogging the soil. Monitor the soil moisture levels regularly and adjust your watering frequency accordingly. Sweet Potato Fertilizer Requirements Sweet potato fertilizer requirements are pretty low. They are not heavy nitrogen feeders like many other crops. Too much nitrogen can lead to excessive vine growth at the expense of tuber development. Therefore, avoid high-nitrogen fertilizers, especially during the later stages when growing the tubers is the priority. Phosphorus and potassium are important for root development and tuber formation in sweet potatoes. I like to rake in some bone meal and some compost in my sweet potato beds at planting. About 60 days in, I might add an organic granular fertilizer with a higher ratio of phosphorus (P) and potassium (K) relative to nitrogen (N), such as a 5-10-10 or similar formulation. Avoid applying fertilizer too close to harvest, as this can affect the quality and storability of the tubers. Incorporating organic matter, such as compost or well-rotted manure, into the soil before planting can satisfy sweet potato fertilizer requirements. Compost provides a slow-release source of nutrients for sweet potatoes. Organic matter also helps improve soil structure, moisture retention, and microbial activity, which are beneficial for overall plant health. Pruning Pruning of sweet potato vines is typically done during the mid to late growing season, usually around 60-90 days after planting. This timing allows the vines to establish and spread adequately before pruning while still leaving sufficient time for tuber development before harvest. Sweet potato vines can grow quite vigorously, and excessive vine growth may divert energy away from growing tubers. As a general guideline, consider pruning the vines when they reach a length of about 12 to 18 inches beyond the planting hills or mounds. Keep in mind that while pruning can help promote sweet potato growth, excessive pruning or pruning too early in the growing season can stress the plants and reduce overall yields. Strike a balance between controlling vine growth and allowing enough foliage to support the plants’ energy needs. Tuberous Roots in Your Container Garden? You can grow sweet potatoes in containers, although there are some considerations to keep in mind to ensure success: Container Size: Choose a container that is at least 12 inches deep and wide enough to accommodate the spreading growth of sweet potato vines. Larger containers, such as half-barrels or large pots, will provide more space for root development and allow for a higher yield. Drainage: Ensure that the container has adequate drainage holes to prevent waterlogging, as sweet potatoes do not tolerate waterlogged soil. Adding a layer of gravel or broken pottery shards to the bottom of the container can improve drainage. Soil: Use a well-draining potting mix that is rich in organic matter. A mix of equal parts potting soil, compost, and perlite or coarse sand works well for growing sweet potatoes in containers. Variety Selection: Choose compact or bush-type sweet potato varieties suited for container growing. These varieties tend to produce smaller vines and are better suited for confined spaces. How to Propagate You can make your own slips for next year’s sweet potato crop. Start by selecting healthy, disease-free sweet potatoes to use for sprouting slips. Place the sweet potatoes in a warm, humid environment to encourage sprouting. You can do this by placing them in a box or tray of potting soil. Keep the sweet potatoes in a warm location with temperatures around 75-85°F (24-29°C). Before you know it, your potatoes will begin to grow their own vines. Let them get to be about 6-8″ tall before gently pulling them off of the tubers. Place the vines in a jar of clean water, and watch them grow their own roots. Once the roots are 6-8″ long, they’re ready to plant. Alternatively, you can snip off some healthy vine cuttings from your existing plants, and root them in clean water. If you continue to do this after your first year planting, you’ll always have free slips to re-plant. Slips don’t have any sweet potato fertilizer requirements. They just need clean water and sunlight. Insect Pests The most common pest that I have in my sweet potato is the flea beetle. Flea beetles are small, dark-colored beetles that feed on the leaves of sweet potato plants. They create small holes in the foliage, which can lead to reduced photosynthesis and plant vigor. They aren’t usually a huge problem, and spinosad generally takes care of them. Other pests that you may find giving you a hard time are slugs and snails, root-knot nematodes, white flies, cut worms, and spider mites. We have more specific treatments for all of these pests in our organic vegetable garden pest control post. Disease Problems Sunlight helps to dry out the soil and foliage, reducing the risk of fungal diseases and rot. Shaded areas tend to retain more moisture, which can create a conducive environment for diseases to develop. Black rot is the most common fungal disease that affects sweet potato plants, causing dark, sunken lesions on the tubers and stems. It can lead to decay of the tubers and reduced storage life. To manage sweet potato diseases, it’s essential to practice good cultural practices, such as crop rotation, sanitation, and selecting disease-resistant varieties. If disease symptoms are observed, it’s important to promptly remove and destroy affected plant material to prevent further spread. Weed Control Soon after planting, you’ll find that your sweet potato plants may be competing with weeds. Keep those weeds at bay with mulch or carefully cultivate between your plants. Later, as the vines spread, the ground will become shaded, and weeds will struggle to grow beneath the sweet potato vines. Time to Harvest Most varieties of sweet potato roots need around 120 days from planting to harvest. Before harvesting, carefully loosen the soil around the base of the sweet potato plants using a garden fork or shovel. Be gentle to avoid damaging the tubers. Once the soil has been loosened, carefully dig around the base of the plants to expose the harvestable roots. Use your hands or a garden fork to gently lift the tubers out of the soil. Take care not to puncture or bruise the tubers during the digging process. Curing You can eat your sweet potatoes right away. We often do, and they’ve been really great. However, for a sweeter tuber, store your sweet potatoes in a warm, dark space for two weeks. The tubers will condense their starches down to sugar, making them sweeter. The skins will toughen up to keep them long lasting in storage. Long Term Storage Sweet potatoes store well in a root cellar that remain above 55°F, as anything lower will cause them to rot. The space that you store them in should be cool and dry also. High humidity will cause them to rot as well. Here in Florida, we don’t have root cellars or basements, so we keep them in a dark pantry for as long as we can. If they start to soften, we skin them, cube them, and pressure can them. Quarts need 90 minutes under pressure, and pints need 65 minutes. Summary – Sweet Potato Fertilizer Requirements: Growing Guide I hope that we answered all of your sweet potato fertilizer requirements questions and then some. If you follow this detailed growing guide, you’re sure to have a bountiful crop of sweet potatoes this season. Happy growing! Donna @ Hazel Belle Farm Donna and her family have been homesteading for most of their 20+ years together in some shape or fashion. She currently lives on their 20 acre farm where they grow as much food as possible. What started as a just a few laying hens, has grown into large gardens, pastured poultry, pork, and lamb. They are continuously evolving their small farm to not suit their family’s needs, but also providing to their local community. Donna’s favorite part of the family farm is her self-built micro-dairy, where she gets to love on dairy cows while serving her local community. Milking, cheesemaking, and processing dairy have become the soul of their homestead and the center of their farm. Gardening Homesteading