Sweet potatoes produce best in a well-drained, light, sandy loam or silt loam. soil. Rich, heavy soils produce high yields of low-quality roots, and extremely poor, light sandy soils generally produce low yields of high-quality roots. Both surface and internal drainage are important in selecting a field.
Sweet potato vines thrive best when a balanced slow-release 10-10-10 or 12-12-12 fertilizer is applied. Use either organic or non-organic fertilizer since this plant will not produce an edible crop.
Sweet potatoes need at least 1 inch of water per week to grow well. Watering is especially important during the transplant, establishment and root development period. Stop watering the sweet potatoes three to four weeks before harvest to prevent tubers from splitting.
Potted sweet potatoes prefer well-draining, sandy soil to which you should add compost. Plant your yam slips 12 inches (31 cm.) apart. Keep the potted sweet potato start indoors for 12 weeks before moving it outside, at least four weeks after the last frost.
Farmers propagate sweet potato vegetatively, using vine cuttings. Cuttings from the TIPS of the vine are the best planting material. Cuttings from the MIDDLES and the BASES of the vine can be used, but they usually produce lower yields. Also, cuttings from the BASES of the vine more often carry weevils.
The long vines of sweet potatoes can overrun a garden. In early to mid-September, feel free to cut them back by 25%. This simply makes the plants easier to deal with when digging. Sweet potatoes with edible tubers developing below the ground.
How many sweet potatoes do you get from one plant? Typically, you'll be able to harvest 3-5 tubers per sweet potato plant, which is about 1-2 pounds. But if you live in a warmer climate, you may harvest six or more tubers per plant.
Lack of soil fertility and improper cultivation systems will reduce the productivity of sweet potatoes (Ipomoea batatas L.) significantly. Effort to increase the productivity of sweet potato can be achieved by administering of cow dung and managing the height of mounds to support the crops growth and development.
Epsom salt. Add some Epsom salt to the soil while planting to help promote magnesium which will help build walls of Sweet Potato. For a more direct approach, 1 tablespoon can be mixed with a gallon of water and applied directly as a foliar spray on the leaves.
Sweet potatoes mature in 90 to 170 days and they're extremely frost sensitive. Plant in full sun three to four weeks after the last frost when the soil has warmed. Make holes 6 inches deep and 12 inches apart. Bury slips up to the top leaves, press the soil down gently but firmly, and water well.
Growing Sweet Potatoes: The Initial Feeding
In the past, I've also used amendments such as lime, blood meal, bone meal, cottonseed meal, and kelp meal—all of which are excellent additions to the soil.
Rather than “hilling” sweet potatoes (like you do regular spuds) the seedlings are planted 10-18” apart on mounded-up rows that are 8-12” high. Rows should 3' apart to allow for sprawling vines. Transplant in the evening and water well; keep the soil moist for the next few days and then back off watering to sparing.
You can harvest sweet potatoes as soon as they reach a usable size, which takes at least three months. Harvest a few tubers to see if they're large enough before digging the entire patch. Plan to dig all sweet potatoes before frost.
Harvesting sweet potatoes
Harvest roots as soon as they reach eating size and before a frost. Sweet potatoes generally mature in 85 to 120 days. Check root size after 80 to 85 days because they don't stop growing and can start to split when overgrown. Digging is easier if you cut the vines off first.
Bone meal, kelp meal, and green sand are my favorite organic choices for sweet potatoes that are lower in nitrogen than potassium and phosphorus. Don't over-fertilize! Sweet potatoes are not heavy feeders, so these should just be an occasional snack if your soil is less than ideal.
Sweet potatoes are warm-season plants that are very sensitive to cold temperatures. The tuberous roots should be harvested by the time frost kills the vines or soon thereafter. Sweet potato roots continue to grow until frost kills the vines.
Ornamental sweet potato vines will come back every year if you live in a warm enough climate (zones 9+). However, they will not survive outside through the winter in colder climates.
Propagating Ornamental Sweet Potato Vines
You can store them like bulbs and plant them in containers the next spring. After you've cleaned out your containers for the season, rinse off the tubers and let them dry completely. Then keep them in a cool place (like a basement) throughout the winter.
Sweet potato vines like to grow in moist but not wet soil. Water them once a week if no natural rainfall occurs. Water more frequently during unusually hot weather or if the sweet potato vine is part of a container garden. Overwatering causes the root system to rot.
Soil and Spacing: Sweet potatoes prefer a fertile, well-drained, loose, deep, slightly acidic, fine sandy loam or very sandy soil. A soil pH of 5.5-6.5 is perfect for better growth. Develop problem soils by adding compost/well-rotted manure and organic matter, prior to planting.
Sweet potatoes should be mulched soon after planting. If you're in a warm area where black plastic isn't required straw or old leaves can be used. This will help keep the soil moist and block out weeds.