Crop name: Sweet Potato
Scientific name: Ipomeoea batatas
Family name: Convolvulaceae
Cultivar groups: orange flesh and white flesh
Warm season or cool season: Warm Season
Planting instructions: Transplant; slips (rooted sprouts) or vine cuttings placed 4 inches deep in warm, moist sand or soil for about 1 month. Ambient temperature must be at 65F for 4 consecutive days.
Space between plants/between rows 8-12 inches between plants; 32-42 inches between rows; Transplant at 3 inch depth. Plant with at least 2 nodes in the ground and at least 2 leaves above.
Fertility requirements pH 5.8-6.2; Low nitrogen requirement (do not exceed 75 lbs/acre); 30-60lbs/A of P2O5; 50-100 lbs/A of K2O. Boron should remain at 0.5 lbs/A to reduce the incidence of blister.
Watering needs Water weekly, ideal of 1 inch of rain per week
Number of days from seed to transplant and/or seed to harvest Root→slip takes approximately 1 month with at least four consecutive days at 65F. Slip→harvest approximately 90-150 days, or grow until leaves are killed by frost (black leaves harvest immediately)
Pest and Disease Information:
Insect pest considerations Green peach aphid, cutworms, flea beetle, tortoise beetle, slugs, whiteflies, wireworms, and white grubs.
Plant pathogen considerations Root rot, stem canker (rhizoctonia), black rot (Ceratocystis fimbriata), soft rot (rhizopus).
Average yields 12,000-25,000 lbs/A (low→high)
*NE increased production 8x from 2007-2012 due to UNH research
Harvest and post-harvest guidelines:
Continue to grow until leaves are killed by frost or the soil falls below 65F. Harvest when roots look sufficient’ harvest right when the leaves turn black. Be careful not to damage at harvest, skin is prone to wounds, which causes rot. Cure at 80-86F at a relative humidity of 85-95% for 4-7 days. This allows for corky periderm to form. Allow for 3 weeks in-between consumption and harvest for the accumulation of sugars.
Post Harvest Information:
- Crop is ready to harvest when leaves are killed by frost or the soil falls below 65 F; dig up a sweet potato to test and gauge the size. Harvest before the leaves turn black.Typically 110-150 days from the time of planting of slips.
- Carefully dig up potatoes using a spade fork. To reduce mess, clear out vies before going in with a spade fork. Loosen the soil around the plant about 18 inches in diameter. Pull out the crown of the plant and shake off the dirt. Do not wash; allow it to dry 1-3 hours on the ground. Keep from creating any bruises in the potato, as sweets are prone to harvest damage.
- Harvest at any time during the day, preferably morning so the potatoes have time to dry on the ground.
- Do not wash this crop until ready to use.
- Sweets should be cured at 80-86F with a relative humidity of 85-95% for 4-7 days. This will allow for the formation of the corky periderm.
- Sweets should be wrapped in newspaper or other paper materials and packed in a wooden box or basket to be stored in a root cellar (<55F).
- Depending on storage method, sweets can be stored from 6-12 months.
- The largest problem facing sweets is damages to the crop during harvest that are not dealt with accordingly during the curing process. Common losses are the result of improper curing (such as low relative humidities and temperatures too low in the NE).
Farm to YouNH Crop Data: