Growing Sweet potatoes
Planting & Growing from Slips. Sweet potato grown from slips generally need at least 4 months of frost-free growing. I grow and sell Georgia Jets which is an early variety need about 90-120 days from transplanted slips until the full size tubers can be harvested.
Most gardeners start with slips purchased from a local garden center or reputable mail order source. I will have slips available starting in April. Sweet potatoes grow vigorously in warm areas and quickly shade out weeds as the season progresses.
Sweet potatoes prefer loose, well-drained soil. If you have clay soil or drainage problems, work in lots of compost and make raised beds or planting ridges 8 to 12 inches high.
It’s important to plant your slips quickly after they arrive, but wait for warm, settled weather before planting outside. If the weather is still too cold or your garden is not ready, heel in the slips (loosely plant them) in a temporary location (in a flat or nursery bed) for transplanting later.
Don’t worry if your slips don’t have roots, with good care new roots will develop rapidly. Transplant your slips into the ground outdoors 2 to 3 inches deep, with the leaves above the ground, 10 to 18 inches apart in rows at least 3 feet apart (to make room for the sprawling vines). Transplant in the evening and water immediately. Keep the soil moist for the next few days as the plants get established.
In most areas sweet potatoes can produce well without additional watering after the plants are established, but irrigation will assure a larger harvest and even moisture helps prevent splitting and cracks. Keep the plants free of weeds until they are established and can shade out competition. Side dress each plant with a shovel full of compost for better yields and larger sweet potatoes (but sweet potatoes generally produce well with low fertility). Deer are fond of sweet potato vines, so protect your plants from browsers.
Harvesting
You can harvest sweet potato leaves and young shoots for cooking greens at any time during growth (just don’t take too much at once). The sweet potatoes are ready to harvest as soon as they reach your preferred size. Try digging one of your plants when your crop reaches the recommended growing time for the variety (generally between 90 and 120 days.) If the tubers are still too small for your liking, try again in a week.
It’s best to harvest on a sunny day when the soil is not too wet. Begin by pulling aside the vines so you can see where you’re digging. Using a garden fork (or a shovel or spade), begin digging 12 to 18 inches away from the center of the plant to avoid damaging the sweet potatoes. Go straight down about 6 inches, then angle toward the center and gently lift the potatoes out of the ground. Separate the sweet potatoes and let them dry in the sun for no more than one hour. Handle freshly dug sweet potatoes gently to avoid bruising. Or dig out by hand carefully like I do.
Sweet potatoes left in the ground will continue growing until frost, although growth slows as the weather cools. For best storage quality, harvest sweet potatoes before the soil temperature drops below 55°F.
Curing & Storage
Curing allows for healing of any scratches or other damage to the sweet potatoes, develops their sweetness, and improves storage quality. Immediately after harvest, let the sweet potatoes fully dry, then shake off excess soil. Do not wash the sweet potatoes! Cure by keeping them at 90 percent relative humidity and 85°F for seven to ten days. A furnace room or space heater can provide the right storage condition.
For long term storage after curing, choose firm, round, bruise-free, well-shaped sweet potatoes with fairly even coloring. Store in a cool (over 55°F), dry, well-ventilated area away from light. Do not refrigerate sweet potatoes unless they are already cooked. Cold temperatures will give sweet potatoes a hard core and affect the flavor. Properly cured sweet potatoes should store for 5 to 12 months unrefrigerated.
Growing Your Own Slips
If you want to grow your own slips, start six to eight weeks before planting time. Select 1½-2” inch diameter sweet potatoes from high yielding hills. Soak the sweet potatoes in water for two hours, then place them in a flat or pot half filled with soil or screened compost. Cover with 2 inches of loose soil. Keep the soil consistently moist in a warm and sunny spot indoors. When you are ready to plant, cut your slips an inch away from the “mother sweet potato” to avoid transferring any plant diseases. Slips should be 8 to 10 inches long when pulled.