Sweet potatoes are a flavorful, nutrient-rich root vegetable that has been cultivated for thousands of years. Often confused with yams, these golden-fleshed roots are easy to grow and can thrive in many home gardens.
Getting Started: Soil and Site Prep
Sweet potatoes love warmth and grow best in loose, well-draining soil with a slightly acidic pH between 5.8 and 6.2. They aren’t picky about nutrients but dislike heavy clay, which can stunt growth and distort tubers. If your soil is compacted, consider planting in raised beds amended with compost and sand to improve aeration.
In cooler regions, it helps to warm the soil ahead of planting by covering your beds with black plastic or landscape fabric three weeks before planting. These heat-loving plants need consistent warmth, so wait until the danger of frost is long gone before putting them in the ground.
Growing Sweet Potatoes from Slips
Unlike most vegetables, sweet potatoes don’t grow from seeds. Instead, they are propagated from sprouts called “slips.” You can purchase slips or grow your own by placing mature sweet potatoes in moist sand or sawdust in a warm location (75-80°F) about six weeks before planting. When shoots reach 6 to 9 inches long, snip them off, discard the bottom inch to avoid disease, and they’re ready to plant.
Outdoor Planting Guide
Prepare wide mounded rows about 10 inches high and spaced 3 to 4 feet apart. Each slip should be planted 6 inches deep and 3 inches wide, with only the leaves above the soil. Water well after planting and provide daily water for the first week. In hot climates, shade young plants with overturned pots for a few days to protect them.
Expect to harvest your sweet potatoes between 90 and 170 days after planting. Be sure to avoid frost, which can severely damage your crop.
Watering and Mulching Tips
After the first two weeks of frequent watering, reduce to once weekly unless the weather is dry. In drought conditions, aim for an inch of water weekly up until two weeks before harvest. Avoid overwatering, which can lead to rot.
Mulching two weeks after planting helps suppress weeds, retain moisture, and maintain loose soil. Be cautious when handling vines—they bruise easily and can attract disease. Lifting vines gently prevents them from rooting at nodes, which helps focus energy on the main crop.
Side-dress your sweet potato beds three to four weeks after planting with a balanced organic fertilizer like 5-10-10, avoiding high-nitrogen formulas that promote leafy growth over tubers.
Companion Planting and Garden Planning
Sweet potatoes do well alongside root vegetables like carrots, beets, and parsnips. They also pair nicely with ground-trained beans and herbs like thyme, oregano, and dill.
Avoid planting near other aggressive spreaders like squash, as sweet potato vines are known to take over garden space. Raised beds or designated planting areas can help control their growth.
In Southern gardens, consider planting summer savory nearby to deter sweet potato weevils, a destructive pest.
Harvesting Your Sweet Potato Crop
You can harvest sweet potatoes when tubers reach 6 to 8 inches in length or around the time of the first light frost. Warmer climates allow for a longer growing season and potentially sweeter roots.
Before harvesting, clip vines and roll them out of the way. Use a digging fork to carefully loosen the soil about a foot from the plant and gently lift the roots. Be mindful of bruising or damaging the skin—sweet potatoes are delicate at this stage.
Allow the roots to air dry in the sun for no more than an hour. Then transfer them to a shaded area at temperatures above 55°F to avoid chilling injury.
Curing and Storage
Curing sweet potatoes toughens their skin and converts starches to sugars. Store your roots in a warm, humid space (85-90°F) for 7 to 15 days. You can build a DIY curing chamber using an oven with a 40-watt bulb or a cooler with a heating pad.
After curing, keep sweet potatoes in a cool (55-60°F), humid environment for long-term storage. Don’t refrigerate, and avoid rough handling to prevent bruising. Properly stored, they can last for up to eight months.
Growing Your Own Slips
To save slips for next season, select medium-sized, blemish-free sweet potatoes from your most productive plants. Suspend sections in water with toothpicks or bury them in a soil-filled container in a warm, bright area. In a few weeks, shoots will emerge. Remove and root these shoots in water until ready for planting.
Another option is to pot whole tubers at a 45° angle in soil three months before your last frost. When sprouts reach 6 to 12 inches, transplant them outside.
Recommended Varieties
- Jewel: Disease-resistant with long storage life
- Stokes: Deep purple flesh rich in antioxidants
- Centennial: Cold-hardy and ideal for northern gardens
- Bunch Puerto Rico: Compact growth, great for small spaces
- Oriental/Japanese: Nutty flavor, excellent for roasting
- Georgia Jet: High-yielding and quick to mature
Troubleshooting Pests and Diseases
- Sweet Potato Weevil: Small beetles that damage vines and roots. Use resistant slips and rotate crops every four years.
- Black Rot: Causes dark depressions on roots; discard infected tubers.
- Scurf: Harmless discoloration; affects appearance only.
- Stem Rot: Enters through damaged tissue; reduce risk with gentle handling and healthy slips.
- Dry Rot: Caused by improper storage; maintain proper temperature and humidity.
If frost damages your vines, trim them immediately to stop rot from spreading. Harvest can proceed safely if soil hasn’t frozen.
Growing sweet potatoes is both rewarding and surprisingly simple with the right preparation. Follow these steps and you’ll enjoy a hearty harvest of sweet, nutrient-rich roots that store well into the winter months.