Sweet potatoes are not a crop that most vegetable gardeners in Nebraska often consider to be an option. Sweet potatoes are a tropical crop more naturally suited for production in more southern climates. Sweet potatoes are very nutritious in that they are high in fiber, low in fat and contain vitamins A and C. The sweet potato is also commonly confused with the yam which is completely unrelated to the sweet potato.
Produce Your Own Slips
Unlike regular potatoes that are produced from pieces of seed potatoes, sweet potatoes are produced from slips or sprout that arise from the sweet potato itself. Slips can be purchased through garden centers or producers that specialize in slip production for growers that require larger amounts. Slips can also be produced very simply if only a few are going to be planted.
Growing your own sweet potato slips can be a fun family project.
To produce your own slips start with a whole sweet potato and a quart jar. Insert 3-4 tooth picks into the sweet potato around the middle of the sweet potato to act as supports. Place the sweet potato into the jar so one end is in the jar and the other end is out and pointing up supported by the toothpicks. Fill the jar with water and place the jar in a sunny window that will not drop below 50 degrees.
Green sprouts will begin to appear in 2-4 weeks. Let the sprouts grow until they are 6-8 inches long. Remove the slips from the sweet potato and place them in a second jar of water where they will develop roots. You can hold them in the jar until you are ready to plant them outside. The original sweet potato if left in the jar of water will continue to produce slips.
Sweet potatoes require good soil drainage. The preferred soil types range from sandy to sandy loam but most well drained soils will produce a crop. Planting in raised beds is beneficial because the soils will stay warmer and water drainage is increased making planting in heavier soils an option.
Soil pH can be as low as 5.0 but peak performance is achieved at a pH range of 6.5-7.5.
Being of tropical origin, sweet potatoes need to be planted after the danger of frost has past and both days and nights are warm. For producers in Nebraska late May into early June is the perfect time to plant sweet potatoes. Plant sweet potatoes in a ridged row or raised beds. The slips should be planted 3 to 4 inches deep and 9 to 18 inches apart. Water the slips in after planting.
High fertility soils can result in increased foliage growth and reduced tuber yields so initial fertilization should be based on the results of a soil test. Approximately 3 weeks after planting and growth has started, side dress 1 ounce of nitrogen per 100 square feet. A second side dressing using the same amounts can be applied once runners start to grow off the bed.
The top photo shows sweet potato slips ready for planting.
Sweet potatoes are considered drought tolerant but yields suffer greatly under drought conditions. Minimum requirements for optimum yield are approximately 1 inch of water per week.
Weeds can seriously impede the development of the crop. Weed control needs to take place throughout the growing season with the greatest emphasis early in development of the vines. Control can be achieved through chemical or manual means or by using a layer of mulch which helps reduce weeds as well as conserving moisture. Once the vines have covered the bed they act as a natural mulch.
Varieties that are successful in the Midwest are ready to harvest in 90-120 days from planting. The vines leaves begin to turn yellow indicated that they are ready for harvest. With some varieties this may be just prior to frost. Light frost will kill the vine but not harm the sweet potato itself but they should be dug if this should happen.
Care needs to be taken during harvest. The skin is very thin and easily damaged increasing the chance of rot. The tubers are also very fragile at this point and break easily so lift them from the ground as gently as possible.
Do not wash them after harvest. If they are muddy wipe them off as best as possible. Air dry them in a warm, shaded area with high humidity for 4 to 6 days. Proper curing toughens the skin and promotes healing of any damage as well as increasing the sugar levels and intensifying the orange color of the flesh. As they dry much of the dirt will fall away.
Wash the tubers just prior to marketing or use. Sweet potatoes can be stored for 6-10 months at 55-60 degrees.
- Beauregard -- 95 to 100 days. Early maturing, light red skin. Excellent shape and yield. Good storage sweet potato.
- Jewel-- 115 to 120 days. Blocky sweet potatoes with copper skin and orange flesh. Very good quality. Does best in light-textured soils.